Food Microbiology

Romanian bors, a traditional fermented wheat bran beverage, is produced through spontaneous fermentation and represents a complex microbial ecosystem. Despite its cultural importance and presumed health benefits, its microbial ecology and functional potential remain poorly characterized. The present study aimed to elucidate the microbial community structure of bors and link it to functional traits relevant to fermentation performance and food functionality by integrating culture-independent sequencing with culture-dependent isolation and functional characterization. A total of 32 bors samples (12 commercial and 20 homemade) were analyzed. Amplicon-based sequencing revealed a microbiome dominated by lactic acid bacteria (LAB), with lactobacilli accounting for the majority of the bacterial communities and Lactobacillus amylolyticus being identified as the most prevalent and abundant species. The yeast communities were mainly composed of fermentative taxa, including Pichia kudriavzevii and Kluyveromyces marxianus. Lactobacillus amylolyticus and P. kudriavzevii were also the most frequently isolated species among bacteria and yeasts, respectively. These results highlighted a strong adaptation of the microbial isolates to starch-rich cereal substrates and underscored the central role of these microorganisms in wheat bran fermentation for bors production. Whereas the sequencing-based analyses showed no significant differences in overall diversity between the commercial and homemade bors samples, the cultivation-based results indicated a higher bacterial richness in the commercial products. Notably, the culture-dependent method captured substantially fewer taxa, highlighting the complementary nature of the two approaches. Of a total of 101 bacterial strains (88 LAB and 13 acetic acid bacteria) isolated, many exhibited rapid growth and strong acidification capacity, reaching pH values below 4.5 within 12 h. A functional screening revealed that 21 % of these strains displayed -amylase activity, 65 % phytase activity, and 50 % {beta}-glucosidase activity, highlighting their capacity to metabolize cereal substrates and enhance the nutrient availability of bors. All strains showed antibacterial activity against at least one indicator bacterium tested, with a universal inhibition of Listeria monocytogenes. Overall, Romanian bors harbored a lactic acid bacteria-dominated core microbiome with a significant functional diversity. These findings underscored its potential as a rich source of functional and technologically important strains for application in starter and protective culture development.

In many tropical countries, fermentation of palm sap into palm wine is an important fermented beverage contributing to local economies, tradition, and culture. Traditionally made in villages and families, palm sap is not inoculated with starter cultures and fermentation commences spontaneously. It is therefore possible that fermentation is influenced by multiple ecological factors, which affect microbial dynamics and thus flavour outcomes. Here, we studied microbial communities during fermentation of palm sap from three different palm tree species (palmyra, coconut, and sugar palm) on the island of Bali, Indonesia in both the wet and dry seasons. Our results suggest that season of collection has a strong influence on microbial dynamics and succession, and these changes positively correlate to metabolite concentration. The change of the season from the dry to wet season led to the loss of microbial diversity with lower richness in the dry season. The dominance of Saccharomyces cerevisiae was not affected by season and fermentation time and was dominant in all samples. Potential spoilage species, such as Candida tropicalis were negatively correlated to ester production and more abundant in the dry season. As microbial species varied in incidence and thus biochemical activity, the chemical groups of esters from their metabolism related to the change of season and fermentation time, while volatile compounds and small molecules were highly discriminated by season in the resultant wines. Ethyl octanoate was consistently different across all variables through comparison by three-way ANOVA and is proposed as a biomarker of seasonal variation in palm sap fermentation. These findings improve our understanding of microbial dynamics in palm sap fermentation, revealing flavour differentiation within season and suggests that strategies for microbial management, product development and quality assurance will elevate this traditional product into the future.

Climate change and eutrophication are driving the expansion of the range of Vibrio species, including V. parahaemolyticus. This bacterium is a major foodborne pathogen and understanding the biogeography of virulent strains of this species is crucial for ensuring food safety. Whole-genome sequencing (WGS) provides strain-level identification of bacteria and is widely used for tracking bacterial pathogens; however, WGS is costly and labor-intensive. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides a rapid, accurate, and cost-effective method for bacterial identification; however, the resolving power of MALDI-TOF MS and WGS for V. parahaemolyticus has not been systematically compared. In this study, 70 V. parahaemolyticus strains were isolated from oysters (Crassostrea virginica) collected from the Gulf Coast and Massachusetts. Oysters were collected in Galveston Bay (Texas) and aquaculture plots in Massachusetts, and purchased from seafood markets in Texas and Louisiana in the U.S. For comparison, two isolates of V. anguillarum were cultured from the exoskeleton of blue crabs purchased from a seafood market in Seabrook (Texas). All isolates were identified using the MALDI Biotyper system and analyzed with custom R scripts. Cluster analysis of mass spectra generated by MALDI-TOF MS, and phylogenomic analysis revealed distinct clusters corresponding to the source of oysters. In both the mass spectra and WGS analysis, V. parahaemolyticus strains isolated from Massachusetts formed a coherent cluster. For comparisons between species, cosine similarities of mass spectra generated by MALDI-TOF MS ranged from 0.43 to 0.59, and average nucleotide identity (ANI) values generated by WGS ranged from 76% to 77%. For comparisons within species, cosine similarities of mass spectra ranged from 0.68 to 0.91 and ANI values ranged from 98% to 100%. This suggests that MALDI-TOF MS has a resolution comparable to WGS and can be used to track strains of V. parahaemolyticus associated with oysters.

Biopreservatives including nisin and its derivatives are becoming more desirable in the food processing industry because of the growing demand for naturally preserved and minimally processed foods free from artificial preservatives. However, ensuring microbiological safety while meeting these consumer preferences remains a major challenge. This has necessitated the continuous investigation of potential new antimicrobial agents produced by naturally occurring microorganisms. Hence, this study explored the synthesis, characterisation, and optimisation of a bacteriocinogenic lactic acid bacterium and its antimicrobial product, possibly novel bacteriocin (Nisin 2A) from Lactococcus lactis isolated from commercial brined cheese. The isolation was achieved by screening for wild-type bacteriocin-producing lactic acid bacteria from dairy products using MRS media. Screening was performed using antagonism assays, yielding five producer organisms. Of these, the isolate whose metabolites exhibited the most potent antimicrobial activity was identified as Lactococcus lactis, which synthesised an active antimicrobial peptide designated as Nisin 2A, with a molecular mass of approximately 3.3 kDa as determined by UHPLC-MS and SDS-PAGE. Production of Nisin 2A was scaled up through fed-batch fermentation of Lactococcus lactis in modified MRS broth following process optimisation using a Plackett-Burman experimental design and purified by ammonium sulphate precipitation and solid-phase extraction (SPE). Furthermore, the antimicrobial potential of the bacteriocin was evaluated by the agar well diffusion assay and quantified using the tube dilution method. The purified peptide demonstrated broad-spectrum antimicrobial activity, particularly against the test Gram-positive bacteria Bacillus cereus and retained its bioactivity across a wide pH range (3-9) and high thermal conditions (up to 100 {degrees}C). Furthermore, it had high sensitivity to proteolytic enzymes (Proteinase K and Trypsin). Notably, the peptide was thermostable and retained up to 90% of its initial activity after thermal treatment and maintained consistent inhibitory performance after extended storage. These findings highlight the potential application of Nisin 2A as a natural biopreservative in food systems.

Salmonella is a pathogen linked to foodborne outbreaks, including low-moisture foods. Its ability to resist desiccation can contribute to the formation of dry surface biofilms (DSB). This study evaluated the impact of 3 DSB formation protocols (P1=48-h hydrated phase/48-h dry phase, P2=24-h/120-h and P3=8-h/48-h) on the resistance of Salmonella DSB to 70% alcohol, a commercial product (based on 0.015% quaternary ammonium and 25% isopropyl alcohol), gaseous ozone (45 ppm), hot air (90 {degrees}C) and UV-C light (254 nm). The type of DSB protocol impacted the efficacy of the sanitizers (p < 0.05). The biofilm with the shortest hydration phase showed the greatest susceptibility; three out of the five sanitizers evaluated (70% alcohol, commercial product, and UV-C) promoted significant reductions in P3, with counts below the detection limit (0.8 log CFU/cm{superscript 2}) after 5 to 15 min exposure. Regarding protocols P1 and P2, in general, the best performance was from UV-C, especially against DSB on polypropylene, where it achieved reductions of 1.3 log CFU/cm{superscript 2} for P1 and 2.9 log CFU/cm{superscript 2} for P2 after 15 to 30 min of exposure. In contrast, hot air and ozone showed less effectiveness, with reductions [&le;]1.2 log CFU/cm{superscript 2}. In most scenarios, confocal microscopy images corroborated the plate count results (log CFU/cm{superscript 2}). In summary, our data indicates limited action of dry sanitizers on Salmonella DSB, requiring validation and optimization of sanitization processes to ensure the microbiological safety of low-moisture products.

This study investigates electro-fermentation candida Tropicalis SY005 to address fermentation kinetics limitation during grape must fermentation. In comparison with non-stimulated control sample, EF substantially enhanced sugar depletion, TSS drop by day 3 and generated a strongly reduced state (ORP -100 to -143mV). The oxidation-reduction shift enhanced cellular NAD+ regeneration, reducing total fermentation duration from 264 h to 72 h. GC-MS analysis showed pronounced major characteristic volatile compound confirming substantial metabolic pathway shifts in flavor of glycolytic flux. Moreover moderate electric field promoted cellular membrane electropermeabilization substantially promoting bioactive extraction.

Food production is a significant contributor to global greenhouse gas emissions and deforestation, exacerbated by substantial food waste. Converting food waste into yeast protein offers a sustainable solution to enhance food security and contribute to a circular economy. However, due to the diverse and variable nature of food waste substrates, numerous experimental trials are required to optimise the preprocessing steps, yeast strain selection, nutrient addition, and fermentation conditions. This study presents a hybrid modelling approach where data-driven machine learning is used to predict microbial growth kinetics from process parameters. The hybrid model was trained on a comprehensive dataset consisting of 963 fermentation experiments from 55 publications, enabling transfer learning across 46 yeast strains and 79 food waste substrates. The hybrid modelling method was integrated with Bayesian optimisation, a sequential strategy to optimise expensive-to-evaluate functions, to efficiently maximise yeast biomass growth from different food waste substrates. The utility of the hybrid model was evaluated using five test datasets selected from previous literature and was shown to facilitate an average reduction of 66% in the number of experimental trials required to identify optimal fermentation conditions compared to without using the hybrid model. This proved that the transfer of knowledge between yeast strains and food wastes improved the optimisation efficiency of real, previously published datasets compared to traditional optimisation methods. The novelty and contributions of this study include the collation of the extensive dataset, provided as supplementary material; and the demonstration that transfer learning by training the hybrid model on this heterogeneous dataset can improve the optimisation efficiency for yeast biomass growth on new strains and substrates.

Background: Retail red meat may act as a source of foodborne pathogens, antimicrobial resistant bacteria, and antibiotic residues, posing a significant public health concern in Bangladesh. Objectives: This study aimed to isolate and identify major bacterial pathogens from retail red meat, determine their antimicrobial susceptibility patterns, assess the prevalence of antibiotic resistant bacteria, and detect antibiotic residues in meat samples. Methods: A cross-sectional study was conducted from January to June 2019 using 60 retail red meat samples (20 cattle, 20 goat, and 20 buffalo) collected from Rajshahi and Naogaon districts. Bacterial isolates were identified using standard cultural, morphological, staining, and biochemical techniques. Antimicrobial susceptibility was evaluated by the Kirby Bauer disc diffusion method according to CLSI guidelines. Antibiotic residues were screened in 15 representative samples using thin layer chromatography (TLC). Results: Overall prevalence of Escherichia coli, Salmonella spp., and Staphylococcus aureus was 10.0%, 13.3%, and 28.3%, respectively. E. coli showed complete resistance to penicillin (100%) and high resistance to amoxicillin (83.3%), while remaining highly susceptible to ciprofloxacin (83.3%) and gentamicin (66.7%). Salmonella spp. exhibited highest resistance to penicillin (87.5%) and tetracycline (75.0%), whereas gentamicin (87.5%) and ciprofloxacin (75.0%) remained the most effective agents. S. aureus demonstrated marked resistance to penicillin (94.1%), ampicillin (58.8%), tetracycline (47.1%), and amoxicillin (47.1%), but high susceptibility to gentamicin (88.2%) and ceftriaxone (70.6%). TLC detected ciprofloxacin and oxytetracycline residues in one cattle meat sample each (6.7%). Conclusions: Retail red meat marketed in the study areas harbored multidrug-resistant bacterial pathogens and detectable antibiotic residues, highlighting potential risks to food safety and public health. Continuous surveillance, prudent antimicrobial use, improved slaughterhouse hygiene, and strict compliance with antibiotic withdrawal periods are essential to minimize antimicrobial resistance and residue contamination.

Nisin is a promising antimicrobial peptide widely used in food preservation due to its efficacy against Gram-positive spoilage and pathogenic bacteria. Although Nisin is increasingly applied in the food sector, the biopeptide suffers from instability within food matrixes and can rapidly lose its antimicrobial potential following interaction with food biomolecules. Thus, it is necessary to investigate approaches that can be employed to extend the stability and activity of Nisin. Hence, the aim of this study was to develop and characterise a chitosan-alginate polyelectrolyte microencapsulation system capable of enhancing Nisin stability while retaining antimicrobial activity. The microencapsulation of Nisin was achieved by pre-gelation of alginate using calcium chloride and subsequent direct electrostatic interaction between cationic Nisin and chitosan with pre-gelled anionic alginate at pH 5.0. Following microcapsule formation, physicochemical and structural characterisation was performed using Zeta potential determination and measurement of the polydispersity index (PDI) via dynamic light scattering. SEM micrographs were used to confirm morphology, while Fourier-transform infrared (FTIR) spectroscopy and high-performance liquid chromatography (HPLC) were utilised to assess chemical integrity and functional group preservation of encapsulated Nisin. Following this, stable microcapsules with diameters ranging from 150-200 nm and smooth surface morphology were obtained. Microcapsule formation was strongly influenced by formulation parameters, particularly pH, calcium ion concentration, and chitosan content, with deviations from optimal acidic conditions (< pH 5.0) resulting in aggregation, increased polydispersity, and reduced encapsulation efficiency. The microcapsules were monodispersed (PDI {approx} 0.30) and electrostatically stable, exhibiting a Zeta potential of approximately +36 mV. These microcapsules remained stable over a prolonged storage period of 21 days under refrigerated conditions while retaining antimicrobial activity against Bacillus cereus. Encapsulation efficiency reached approximately 65%, confirming effective retention of Nisin within the polymer matrix. Overall, the findings demonstrate that chitosan-alginate ionic gelation is a non-denaturing and effective encapsulation strategy for extending the functional stability of Nisin. These microcapsules show strong potential as natural antimicrobial delivery systems for food and beverage applications, particularly in acidic food matrices, with implications for improved food safety and shelf-life extension.

"Lactic acid bacteria (LAB) are one of the dominant groups of bacteria in the palm sap (Arenga pinnata) microbiome. Previous research in the sago palm sap production centers of Tomohon City (Kayawu, Pinaras, and Lahendong) has successfully identified various LAB species, including Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus buchneri, Leuconostoc mesenteroides, and Leuconostoc sp. This study aims to identify LAB species in sago palm sap from a new location, namely the Wawo Plantation in Tomohon, and to evaluate their potential as natural antibacterial agents. Through 16S rDNA gene sequencing analysis, the isolates obtained were identified as belonging to the newly described genera Lacticaseibacillus and Lactiplantibacillus. Four promising isolates Lactiplantibacillus fabifermentans A1.4, Lacticaseibacillus casei B1.5, Lacticaseibacillus paracasei B1.6, and Lacticaseibacillus paracasei B3.5 were tested for their inhibitory activity against the enteric pathogens Salmonella sp. and Escherichia coli using the well diffusion method. The results showed that all isolates exhibited a strong spectrum of pathogen inhibition. The highest inhibitory activity against Salmonella sp. was demonstrated by the L. paracasei B1.6 isolate, with an inhibition zone of 21.25 mm, while optimal inhibition against E. coli was achieved by L. casei B1.5 at 11.0 mm. These findings confirm that the local BAL strain from Tomohon palm sap has great potential for large-scale development as a biopreservative in the food industry and as a functional probiotic agent"

Traditional Mongolian fermented foods have been extensively utilized for dietary regulation and the promotion of gastrointestinal health. However, spontaneous fermentation remains inherently unpredictable, leading to significant variations in microbial community dynamics, metabolite accumulation, and the consistency and quality of the final product. Drawing on the traditional preparation of Mongolian acidic foods, this study established a controlled production strategy for whole-wheat probiotic fermented soup (WWPFS) by combining enzymatic pretreatment with probiotic-directed fermentation. Physicochemical characterization, 16S rRNA gene-based microbial community profiling, LC-MS/MS-based untargeted metabolomics, safety evaluation, and an Escherichia coli-induced gut microbiota dysbiosis model were employed to optimize and comprehensively characterize the fermentation process of WWPFS. The optimized process established a reproducible fermentation system consistently dominated by Lactobacillus and Bacillus across independent fermentation batches. Compared with traditional spontaneous fermentation, probiotic-directed fermentation remodeled the physicochemical properties of the whole-wheat matrix, including carbon, nitrogen, phosphorus, sulfur, and mineral composition, and facilitated the accumulation of putatively annotated LC-MS/MS features, including DL-lactate, 1,4-D-xylobiose, diacetyl, and phenyllactic-acid-related features derivatives. Acute oral and 28-day repeated-dose toxicity evaluations showed no treatment-related adverse effects within the tested dose range and study duration. In the Escherichia coli-induced gut microbiota dysbiosis mouse model, microbial richness, diversity, and community structure differed among the experimental groups, and both low- and high-dose WWPFS groups showed significant shifts in overall gut microbial community composition relative to the model group after multiple-testing correction, together with directional recovery of selected model-responsive bacterial genera. Cross-system integration identified coordinated response patterns between fermentation-derived metabolite features and model-responsive gut bacterial taxa, supporting a potential metabolite-microbiota link in WWPFS-mediated gut microbiota modulation. In summary, probiotic-directed fermentation improved the controllability of the traditional Mongolian fermented food production process, reshaped its metabolic profile, and enhanced its potential to modulate the gut microbiota. These findings provide experimental evidence supporting the modernization of traditional Mongolian fermented foods and the development of probiotic-based functional foods.

BackgroundReliable detection of Salmonella remains a major challenge for public health surveillance and food safety due to the growing diversity of circulating serovars and the limitations of existing molecular targets. This study aimed to identify an optimal molecular target and develop a TaqMan real-time PCR assay for the detection of Salmonella spp. MethodsBased on the results screening for Salmonella genes suitability as molecular markers, a TaqMan real-time PCR assay targeting the hilA gene was developed and validated. Analytical sensitivity, analytical specificity, and performance on bacterial isolates and artificially contaminated food samples were assessed. ResultsAmong all candidate targets, hilA demonstrated the broadest coverage and was detected in all tested Salmonella isolates, including representatives of rare serological groups, whereas invA conventionally used for this pathogen detection, was absent in a subset of strains. The assay exhibited a limit of detection of 100 bacterial cells/mL and 100 fg/L of genomic DNA. No cross-reactivity was observed with DNA from Shigella flexneri, Shigella sonnei, Yersinia pestis, Y. pseudotuberculosis, Y. enterocolitica, Y. kristensenii, Bacillus anthracis, Vibrio cholerae, or Francisella tularensis. The assay successfully detected Salmonella DNA in all artificially contaminated food samples tested. Evaluation using a collection of 25 bacterial isolates demonstrated positive amplification in all 24 confirmed Salmonella strains, while a strain initially identified by conventional bacteriology as Salmonella but subsequently confirmed by whole-genome sequencing as Proteus mirabilis yielded a negative result. ConclusionsThe hilA gene represents a highly conserved and reliable molecular target for the detection of Salmonella spp. The developed TaqMan real-time PCR assay demonstrated high analytical sensitivity, excellent specificity, and broad serovar coverage, supporting its application in laboratory detection of Salmonella, food safety monitoring, and epidemiological surveillance.

The aim of this study was to evaluate the impact of two sustainable dietary protein sources on the structure and composition of the gut microbiota in European sea bass (Dicentrarchus labrax) juveniles. These protein sources were incorporated to the aquafeeds containing (a) Lupinus albus meal, treated with either exogenous enzymes (Solid state hydrolysis-SSH) or fermented with Saccharomyces cerevisiae (Solid state fermentation, SSF) and (b) Lagocephalus sceleratus meal. In the first case (a), the control aquafeed simulated a standard commercial diet, containing soybean meal whereas in the rest of the diets soybean meal was partially or totally replaced by hydrolysed or fermented Lupin meal. In the second case (b) the fish were fed Lagocephalus sceleratus unprocessed fishmeal as well as treated at different temperatures to deactivate tetrodotoxin (TTX). A control diet with 30% commercial fish meal was also fed as a reference diet. Both diets in all inclusion levels did not cause any significant gut microbiota change, suggesting their neutral role in this aspect. However, the gut bacterial communities of the fish fed with 12.5% lupin meal inclusion, had increased amino acid biosynthetic pathways suggesting a beneficial effect.

Reliable DNA isolation is a critical prerequisite for PCR-based food authentication, particularly for meat products where complex matrices may compromise DNA quality and amplification efficiency. This study aimed to analytically validate an automated DNA extraction method from meat matrices using Qiagen QIAcube Connect in combination with the DNeasy(R) Mericon Food Kit. Validation parameters included DNA concentration, total yield, purity, integrity, and assessment of PCR inhibitors using real-time PCR targeting the porcine cytochrome b gene. The method produced a mean DNA concentration of 219.5 ng/{micro}L with an average yield of 21,519.7 ng, exceeding predefined acceptance criteria. Agarose gel electrophoresis confirmed DNA fragment sizes larger than the target amplicon, indicating suitability for PCR analysis. Real-time PCR evaluation demonstrated excellent linearity (R2 = 0.99-1.00), amplification efficiencies between 90.34% and 99.84%, and mean {Delta}Ct values of 0.10, confirming the absence of PCR inhibition. These results indicate that the validated automated method is robust, reproducible, and suitable for routine PCR-based meat species authentication in food control laboratories.

The growing demand for sustainable aquafeeds has intensified interest in alternative protein ingredients capable of reducing reliance on fishmeal without compromising fish performance. Here, we evaluated microbial community-based single-cell protein (SCP) as a fishmeal substitute in juvenile Asian seabass (Lates calcarifer) diets in two independent feeding trials of juvenile fish conducted over 49 and 56 days, respectively and compared them to a previous study that lasted 24 days. SCP was produced from nutrient-rich soybean-processing side streams by microbial communities in fermenters and incorporated into experimental diets at inclusion levels ranging from 10% to 100% fishmeal replacement. In the 24-day trial, a diet containing 50% fishmeal replacement with lab-scale produced SCP achieved 100% survival and a feed conversion ratio (FCR), specific growth rate (SGR), and weight gain comparable to the fishmeal control diet. In the 49-day trial using pilot-scale produced SCP, a 50% fishmeal replacement also maintained an FCR and feed intake comparable to the control, whereas complete replacement reduced feed intake and growth performance. In a 56-day pilot-scale trial that used 500-L fish tanks, diets containing up to 50% fishmeal replacement maintained comparable survival, weight gain, and SGR, although moderately higher FCR values were observed at higher SCP inclusion levels. Proximate composition and essential amino acid profiles of fish fed control or SCP-containing diets were comparable. Genome-resolved metagenomic analyses revealed diverse microbial taxa associated with the SCP. Collectively, these findings support microbial community-based SCP as a scalable and reproducible alternative protein platform for aquaculture feeds across independent trials and production scales.

This study evaluates the novel bacteriophage UCB24 as an eco-friendly biocontrol agent against Erwinia amylovora, the bacterial pathogen responsible for fire blight. Following purification, UCB24 was characterized for its optimal multiplicity of infection (MOI), infection kinetics, and environmental stability across diverse pH and temperature ranges. Microtitration assays and scanning electron microscopy (SEM) confirmed distinct morphology of the phage and its potent capacity to disrupt E. amylovora biofilms. Whole-genome sequencing and phylogenetic profiling identified UCB24 as a genetically distinct relative of four known phages. Furthermore, protein-protein interaction analyses revealed a strong binding affinity between the phage lysin and the hosts N-acetylmuramic-acid 6-phosphate etherase, uncovering the precise molecular mechanism driving targeted host destruction. In vivo plant trials demonstrated exceptional protective efficacy in Apple cv. Gala (88.61%) and Quince cv. Esme (81.37%), significantly outperforming traditional copper treatments under severe baseline pathogen pressure. Consequently, UCB24 represents a highly effective and sustainable biopesticide for managing fire blight in susceptible orchard ecosystems.

Raffinose family oligosaccharides (RFOs) are abundant in side streams from food and feed production from legumes, and the transition to plant-based diets increases the volume of such side streams. RFOs in the diet tend to have negative impacts on the consumers gut (e.g., nausea, bloating, diarrhoea), and in many ways, RFOs are comparable to lactose as a side stream from the dairy industry and symptoms associated with lactose intolerance. On the contrary, galactooligosaccharides (GOS) are recognized as prebiotics, and in this study we used a {beta}-galactosidase from Niallia circulans to produce potential prebiotics from RFOs (acceptors) and lactose (donor), which we hypothesized to have a lower fermentability than unmodified RFOs. The transglycosylation reactions resulted in RFO-based -{beta}-GOS, with NMR characterization showing ({beta}1-4) galactosylations on the non-reducing galactose end of RFOs as the major product. In reactions with RFOs, the characteristics were comparable to reactions with lactose alone and the new -{beta}-GOS products made up the largest fraction (by weight). A screening of 11 relevant gut and food microbe strains revealed that the gut commensal Bacteroides ovatus metabolised these modified oligosaccharides for growth whereas other strains grew only after adaption and others did not use them at all. This implies that mixed-linkage -{beta}-GOS are less fermentable by some microbes compared to raffinose, while other (beneficial) bacteria can still ferment them. The enzymatic synthesis established here is an interesting approach to upgrade abundant food side streams towards new prebiotics in a world where functional foods and food waste reduction receive increasing attention. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/731070v1_ufig1.gif" ALT="Figure 1000"> View larger version (22K): org.highwire.dtl.DTLVardef@18e0e62org.highwire.dtl.DTLVardef@1525b4borg.highwire.dtl.DTLVardef@1e7be88org.highwire.dtl.DTLVardef@18df278_HPS_FORMAT_FIGEXP M_FIG C_FIG

Past few decades witnessed a boom in pharmaceutical and bioproduct industry with the help of bioprocess technology. Industrially important bioproducts can be produced in large scale for commercialization with the help of fermenters. Here in, pharmaceutically valuable bioproduct melanin, synthesized from Pseudomonas stutzeri strain BTC109 by using two different sized bioreactors. Under controlled conditions the bacteria were allowed to synthesis melanin nanoparticles. The important parameters to be monitored here are pH, dissolved oxygen, agitation, aeration, melanin production and cell biomass concentration. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=163 SRC="FIGDIR/small/737634v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@d92fe5org.highwire.dtl.DTLVardef@d76c07org.highwire.dtl.DTLVardef@f5516forg.highwire.dtl.DTLVardef@1b5864b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIPharmaceutical and bioproduct development industries witnessed a shoot up due to bioprocess technology. C_LIO_LIIndustrially important bioproduct like melanin can be produced in large scale with the help of industrial fermentation technology. C_LIO_LIThe product thus obtained was found to be nano sized and it can be commercialized. C_LI

Endophytic yeasts of the Metschnikowia pulcherrima clade are recognized as natural producers of pulcherrimin, an iron-chelating red pigment associated with antimicrobial activity. However, endophytic isolates from arid Central Asian fruit trees remain unexplored, and their pulcherrimin biosynthetic capacity is poorly characterized. In this study, five endophytic M. pulcherrima strains were isolated from apricot, persimmon, peach and pomegranate fruits in Uzbekistan and identified using MALDI-TOF MS and ITS sequencing. The strains were cultivated in FeCl-supplemented Sabouraud medium, and pulcherrimin was extracted and quantified using a gravimetric workflow with biological triplicates. Pigment yields ranged from 420.6 to 776.4 mg/L, representing some of the highest values reported for non-engineered isolates under flask conditions. Antimicrobial activity was evaluated by agar well diffusion assays against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans, with inhibition zones reaching 18-23 mm depending on the strain. Nano-LC-MS/MS analysis confirmed the presence of key intermediates of the pulcherrimin biosynthetic pathway, including cyclo(Leu-Leu) and pulcherriminic acid, supporting the metabolic origin of the pigment. These findings reveal that endophytic M. pulcherrima from Uzbekistan fruit trees and shrubs constitute highly productive natural sources of pulcherrimin and represent promising candidates for future fermentation optimization and development of natural antimicrobial pigments. Paragraph on importanceThis study provides the first systematic evidence that endophytic Metschnikowia pulcherrima yeasts isolated from fruit trees in Central Asia possess an exceptional capacity to produce pulcherrimin, a natural antimicrobial pigment. Strains obtained under the environmental conditions of Uzbekistan produced remarkably high levels of pulcherrimin (up to 776 mg/L) under simple, non-genetically modified fermentation conditions, exceeding yields previously reported for yeast and bacterial sources. The iron-chelating mechanism characteristic of pulcherrimin confers broad-spectrum antimicrobial activity against bacteria and yeasts. These findings highlight endophytic yeasts as environmentally safe and sustainable sources of natural antimicrobial pigments and identify Central Asia as a previously unexplored reservoir of high-value microbial resources with significant biotechnological potential.

BackgroundEscherichia coli contamination of chicken eggs is an important food-safety concern, while antimicrobial-resistant E. coli may contribute to the dissemination of antimicrobial resistance through the food chain. However, information on egg-associated E. coli and its antimicrobial susceptibility in Natore District, Bangladesh, is limited. ObjectivesThis study aimed to determine the prevalence of E. coli in chicken eggs collected from commercial farms, markets and indigenous/backyard flocks in Natore District, identify the isolates based on cultural, morphological and biochemical characteristics, and assess their antimicrobial susceptibility. Materials and MethodsA total of 84 egg-shell swab samples, comprising 28 samples each from commercial farms, markets and indigenous chicken flocks, were collected from seven upazillas of Natore District between January and June 2023. Samples were cultured on selective and differential media, and presumptive isolates were confirmed by Gram staining, motility and biochemical tests. Antimicrobial susceptibility was determined using the Kirby-Bauer disc-diffusion method against seven antimicrobial agents. ResultsE. coli was detected in 56/84 (66.67%) egg samples. Prevalence was highest in indigenous eggs (22/28, 78.57%), followed by farm eggs (18/28, 64.28%) and market eggs (16/28, 57.14%). Among 22 confirmed isolates tested for antimicrobial susceptibility, resistance was highest to neomycin (90.91%) and erythromycin (86.36%), followed by oxytetracycline (77.27%), amoxicillin (68.18%), ciprofloxacin (63.63%), levofloxacin (59.09%) and doxycycline (36.36%). No isolate was sensitive to neomycin or erythromycin. ConclusionThe high prevalence of E. coli and substantial antimicrobial resistance among egg-associated isolates indicate an important food-safety and public-health concern. Improved hygienic egg handling, prudent antimicrobial use and continued antimicrobial-resistance surveillance are warranted throughout the poultry production and marketing chain.