Exploring the Relationships Between Bacterial Community, Taste-Enhancing Peptides and Aroma in Thai Fermented Fish (Pla-ra).

As a traditional Thai condiment, Pla-ra is used to add flavor and richness to dishes. Nine treatment combinations of Pla-ra formulations created from 3 types of fish (Mor fish, Kradee fish, and Mor + Kradee fish) and 4 different carbohydrate sources (none, rice bran, roasted rice, and rice bran─roasted rice mixture) were studied through a 12 month fermentation period (1, 3, 5, 7, 8, 9, 10, 11, and 12 months). 16S rRNA Next Generation Sequencing (NGS) and LC-MS/MS techniques were used to analyze the microbial diversity and identify taste-enhancing peptides. Descriptive sensory analysis was performed on the extracts of the 108 Pla-ra samples mixed in a model broth. Koku perception and saltiness-enhancing attributes were clearly perceived and dominant in all samples, even though glutamyl peptides, including γ-Glu-Val-Gly, were found at subthreshold levels. The samples from mixed fish and Mor fish fermented with roasted ground rice and rice bran for 12 months had the most typical Pla-ra odors and tastes and had high taste-enhancing activities. NGS analysis revealed the presence of bacteria containing a large number of protease and aminopeptidase genes in the samples. Bacillus spp., Gallicola spp., and Proteiniclasticum spp. correlated well with the generation of glutamyl and arginyl peptides and typical odors in the samples. These results confirmed the typical sensory quality of Pla-ra depended on protein sources, carbohydrate sources, and bacteria communities. Further optimization of the microbial composition found could lead to the development of starter cultures to control and promote flavor development in fermented fish products.

A combination of omics-based analyses to elucidate the effect of NaCl concentrations on the metabolites and microbial dynamics during the ripening fermentation of Pixian-Douban.

The study investigated the effect of different sodium chloride (NaCl) concentrations (10%, 15%, and 20%) on the ripening fermentation of Pixian-Douban, a traditional fermented condiment. The results showed that NaCl affected the dynamics of physicochemical parameters, volatile components, fatty acids, amino metabolites, organic acids, and microbial composition, and their dynamic modes were different. After 253 days fermentation, the 10% NaCl Pixian-Douban had significantly (p < 0.05) higher levels of total organic acids (20,308.25 mg/kg), amino metabolites (28,144.96 mg/kg), and volatiles (3.36 mg/kg) compared to 15% and 20% NaCl Pixian-Douban. Notably, the possible health risk associated with high concentration of biogenic amines in 10% NaCl Pixian-Douban is of concern. Moreover, correlation analyses indicated that the effect of NaCl on the quality of Pixian-Douban may be mainly related to bacteria. This study deepens the knowledge about the role of NaCl in ripening fermentation of Pixian-Douban and contributes to develop low-NaCl Pixian-Douban product.

Bio-augmented effect of Bacillus amyloliquefaciens and Candida versatilis on microbial community and flavor metabolites during Chinese horse bean-chili-paste fermentation.

Chinese horse bean-chili-paste (CHCP), a fermented condiment in China, is traditionally manufactured through naturally spontaneous semi-solid fermentation procedures without intentionally inoculated microorganisms. The aim of this study was to investigate the effect on microbiota and quality variations during CHCP fermentation by inoculation of selected autochthonous microorganisms Bacillus amyloliquefaciens and Candida versatilis. The results showed that relative abundance of Bacillus in the samples inoculated with B. amyloliquefaciens were increased from about 0.6% to almost 25%, and the batches bio-augmented with C. versatilis exhibited clearly 0.7 Lg copies/g higher biomass than that of the other samples. By bio-augmentation, six enzyme activities, namely acid protease, leucine aminopeptidase, α-amylase, cellulose, ß-glucosidase and esterase, were considerably enhanced. As a result, inoculation of these two strains exhibited significant effect on the volatile profiles of CHCP. B. amyloliquefaciens herein was found to contribute mainly to the accumulation of acids, sulfur-containing compounds and pyrazines, whereas C. versatilis was considerably associated with the formation of alcohols, esters and phenols. This study proved that combination of B. amyloliquefaciens and C. versatilis could obtain more extensive aroma profiles, especially for the enrichment of miso-like and fruity flavors, which could provide a guideline for the tailored control of CHCP fermentation process.

Ester synthesis mechanism and activity by Bacillus licheniformis, Candida etchellsii, and Zygosaccharomyces rouxii isolated from Chinese horse bean chili paste.

BACKGROUND: Esters are indispensable aroma compounds and contribute significantly to the fruity aromas in fermented condiments. The ester synthesis activity and pathways of Bacillus licheniformis, Candida etchellsii, and Zygosaccharomyces rouxii, isolated from Chinese horse bean chili-paste (CHCP), were investigated. Chemical buffer models containing esterification and alcoholysis systems inoculated with extracellular extracts of these three strains were established. RESULTS: The ester synthesis activity of C. etchellsii was stronger than that of the other two strains. Zygosaccharomyces rouxii could synthesize acetate esters via esterification, whereas the biosynthesis pathways of B. licheniformis and C. etchellsii were esterification and alcoholysis. Esterification exhibited relatively high activity at pH 4, whereas alcoholysis activity improved with an increase in the pH from 4 to 8. Candida etchellsii could synthesize C6 -C8 of acetate esters, and its activity improved with the number of alcohol carbon atoms. These three strains could synthesize C10 -C18 of ethyl esters. Their ethyl ester synthesis activity decreased with the aliphatic acid carbon number. CONCLUSION: Candida etchellsii has the potential to be used in CHCP fermentation to accumulate esters and improve flavor compared with the other two strains. This research is helpful in explaining the mechanism of ester synthesis in fermented condiments. © 2021 Society of Chemical Industry.

Deciphering the succession patterns of bacterial community and their correlations with environmental factors and flavor compounds during the fermentation of Zhejiang rosy vinegar.

Zhejiang Rosy Vinegar (ZRV) is a traditional condiment in Southeast China, produced using semi-solid-state fermentation techniques under an open environment, yet little is known about the functional microbiota involved in the flavor formation of ZRV. In this study, 43 kinds of volatile flavor substances were identified by HS-SPME/GC-MS, mainly including ethyl acetate (relative content at the end of fermentation: 1104.1 mg/L), phenylethyl alcohol (417.6 mg/L) and acetoin (605.2 mg/L). The most abundant organic acid was acetic acid (59.6 g/L), which kept rising during the fermentation, followed by lactic acid (7.0 g/L), which showed a continuously downward trend. Amplicon sequencing analysis revealed that the richness and diversity of bacterial community were the highest at the beginning and then maintained decreasing during the fermentation. The predominant bacteria were scattered in Acetobacter (average relative abundance: 63.7%) and Lactobacillus (19.8%). Both sequencing and culture-dependent analysis showed Lactobacillus dominated the early stage (day 10 to 30), and Acetobacter kept highly abundant from day 40 to the end. Spearman correlation analysis displayed that the potential major groups involved in the formation of flavor compounds were Acetobacter and Lactobacillus, which were also showed strong relationships with other bacteria through co-occurrence network analysis (edges attached to Acetobacter: 61.7%; Lactobacillus: 14.0%). Moreover, structural equation model showed that the contents of ethanol, titratable acid and reducing sugar were the major environmental factors playing essential roles in influencing the succession of bacterial community and their metabolism during the fermentation. Overall, these findings illuminated the dynamic profiles of bacterial community and flavor compounds and the potential functional microbes, which were expected to help us understand the formation of flavor substances in ZRV.

Prior exposure to different combinations of pH and undissociated acetic acid can affect the induced resistance of Salmonella spp. strains in mayonnaise stored under refrigeration and the regulation of acid-resistance related genes.

The innate and inducible resistance of six Salmonella strains (4/74, FS8, FS115, P167807, ATCC 13076, WT) in mayonnaise at 5 °C following adaptation to different pH/undissociated acetic acid (UAA) combinations (15mM/pH5.0, 35mM/pH5.5, 45mM/pH6.0) was investigated. The inherent and acid-induced responses were strain-dependent. Two strains (ATCC 13076, WT), albeit not the most resistant innately, exhibited the most prominent adaptive potential. Limited/no adaptability was observed regarding the rest strains, though being more resistant inherently. The individual effect of pH and UAA adaptation in the phenotypic and transcriptomic profiles of ATCC 13076 and WT was further examined. The type (pH, UAA) and magnitude of stress intensity affected their responses. Variations in the type and magnitude of stress intensity also determined the relative gene expression of four genes (adiA, cadB, rpoS, ompR) implicated in Salmonella acid resistance mechanisms. adiA and cadB were overexpressed following adaptation to some treatments; rpoS and ompR were downregulated following adaptation to 15mM/pH5.0 and 35mM/pH5.5, respectively. Nonetheless, the transcriptomic profiles did not always correlate with the corresponding phenotypes. In conclusion, strain variations in Salmonella are extensive. The ability of the strains to adapt and induce resistant phenotypes and acid resistance-related genes is affected by the type and magnitude of the stress applied during adaptation.

Dynamics of physicochemical factors and microbial communities during ripening fermentation of Pixian Doubanjiang, a typical condiment in Chinese cuisine.

As the spirit of Chinese Sichuan cuisine, Pixian Doubanjiang (DBJ) is an indispensable flavor condiment and has been widely used for centuries, which is made from red pepper (Capsicum annuum L.), meju and brine after open ripening fermentation. In this study, the physicochemical factors including pH value, titratable acidity, moisture, organic acids, free amino acids and volatile components etc., were identified; the compositions of microbial communities and representative microbiota were investigated; the correlations between physicochemical factors and representative microbial taxa were analyzed, at different ripening stages. The results indicated that the organic acids were all relatively stable starting from the 12th month; most of the free amino acids (17/20) reached the peak concentrations at the 6th month and 28 volatile components were considered as major odorant flavors in DBJ. Zygosaccharomyces rouxii could be the key microorganism associated with 10 volatile components to the maturing of DBJ flavor. The comprehensive analysis on the physicochemical changes related to the succession of microbiota is expected to help us understand the maturing of the taste and flavor in DBJ production.

The central bacterial community in Pericarpium Citri Reticulatae 'Chachiensis'.

The dried and aged pericarps of Citri Reticulatae are condiments and medicinal products in southeast and eastern Asia for hundreds of years, among which Pericarpium Citri Reticulatae 'Chachiensis' (PCR-C) is the premium one with obvious health benefits. In order to explore the microbiota in PCR-C and their relationship with the chemical components during aging, culture-independent methods were applied to investigate PCR-C microbiota for the first time. Here in different PCR-C samples, 16S rRNA gene amplicon sequencing revealed common central bacterial community, which were absent or only accounted for small proportion in fresh pericarps or jute bag controls. Bacillus and Lactococcus were the top two dominant genera in PCR-C with acidic pH (4.06-4.51) and low moisture (11.48%-19.13%). Several OTUs were found to closely relate with specific compositions in essential oils and phenolics, such as d-limonene and nobiletin, which contributed to PCR-C flavor and quality. As the first study to reveal the central bacterial communities in PCR-C, it provides new insights to improve the quality and aging process of traditional Pericarpium Citri Reticulatae, and lays foundation for functional characterization of the microbes within.

Characterization and comparison of metaproteomes in traditional and commercial dajiang, a fermented soybean paste in northeast China.

Dajiang is a popular Chinese fermented soybean condiment. Here, a comparative metaproteomic analysis of traditional and commercial dajiang was performed during fermentation. A total of 4250 and 1421 peptide sequences were obtained from 3493 and 1987 proteins in traditional and commercial dajiang, respectively. 4299 differentially expressed microbial proteins show a high metabolic heterogeneity between the two types of dajiang. The KEGG annotation indicated that there were some pathways related to human diseases, which suggest that some microbes in traditional dajiang fermentation may have greater food safety hazards. In combination with qualitative metabolomic analysis, we further traced metabolic intermediates and key enzymes in several main fermentation pathways of dajiang to be mainly affiliated with Penicillium, Tetracoccus and Bacillus in traditional samples, as well as Aspergilus in commercial samples. These results could provide information for the selection of strains that are more suitable to produce high quality dajiang and other fermented products.

Head-space gas chromatography coupled to mass spectrometry for the assessment of the contamination of mayonnaise by yeasts.

Head-space (HS) gas chromatography (GC) coupled to mass spectrometry (MS) is proposed for the assessment of the contamination of mayonnaise as an alternative to plate counting, which is the technique commonly used for evaluating microbial contamination. More specifically, this method was applied in the detection of Candida metapsilosis and Zygosaccharomyces bailii, both of great importance in term of food spoilage since they are resistant to many of the common methods of food preservation. Different chemometric models were investigated using the data obtained by GC-MS (m/z profile, area of the chromatographic peaks and entire chromatographic profile), in order to obtain the highest classification success. The best results were obtained using the chromatographic profile (success rate of 92%). Contaminated samples could also be classified according to the concentration of yeast, obtaining a success rate of 87.5%. Finally, a chemometric model was constructed in an attempt to differentiate between strains.

Modelling growth/no growth interface of Zygosaccharomyces bailii in simulated acid sauces as a function of natamycin, xanthan gum and sodium chloride concentrations.

Probabilistic microbial modelling using logistic regression was used to predict the growth/no growth (G/NG) interfaces of Zygosaccharomyces bailii in simulated acid sauces as a function of natamycin, xanthan gum (XG) and sodium chloride concentrations. The growth was assessed colorimetrically by using 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride and 2-methoxy-1,4-naphthoquinone as detection reagents. The logistic regression model successfully predicted G/NG probability. The detection reagents used allowed the evaluation of G/NG interfaces in opaque systems with an excellent agreement with the plate count method. Natamycin concentration of 12 mg/L was needed to inhibit Z. bailii growth independently of the presence of XG and/or NaCl. Addition of 3.00 and 6.00% of NaCl exerted an antagonistic effect on natamycin action. Furthermore, addition of 0.25 and 0.50% XG decreased natamycin and/or NaCl action. However, an increased in XG concentration to 1.00% decreased yeast growth. Mentioned results highlighted the importance of the correct selection of stress factors applied to inhibit Z. bailii growth.

The dynamic changes of chemical components and microbiota during the natural fermentation process in Da-Jiang, a Chinese popular traditional fermented condiment.

There is limited information on the chemical components and microbiota changes involved in da-jiang, a Chinese popular traditional fermented soybean condiment. Therefore, dynamic changes both in physicochemical quality and microbial community diversity of 20 samples of naturally fermented da-jiang collected over 95 days were measured, and we classified the samples into 5 groups (each containing 4 time points) according to the results. Based on OTUs analysis, Group 2 and Group 3 might represent the shift-stage between bacteria and fungi. Also, our results demonstrated that the formation of flavour, nutrient and quality of the traditional da-jiang were actually related to all of microbial community, especially the increased bacteria, including Staphylococcus and Leuconostoc. Correspondingly, 'Membrane Transport', 'Carbohydrate Metabolism', 'Amino Acid Metabolism' and 'Replication and Repair' were the top 4 KEGG pathways based on bacterial genes. The findings are expected to be helpful for us not only to understand the formation of flavour, taste and quality of traditional fermented da-jiang, but also to improve the industrialised fermented da-jiang.

Phylogenetic analyses of bacteria associated with the processing of iru and ogiri condiments.

Analysis of the bacterial community dynamics during the production of traditional fermented condiments is important for food safety assessment, quality control and development of starter culture technology. In this study, bacteria isolated during the processing of iru and ogiri, two commonly consumed condiments in Nigeria, were characterized based on phylogenetic analyses of the bacterial 16S rRNA gene. A total of 227 isolates were obtained and clustered into 12 operational taxonomic units (OTUs) based on 97% 16S rRNA gene similarity. The OTUs spanned three phyla (Firmicutes, Actinobacteria and Proteobacteria), and nine genera: Acinetobacter, Aerococcus, Bacillus, Enterococcus, Enterobacter, Lysinibacillus, Micrococcus, Proteus and Staphylococcus. OTUs closely related to species of Bacillus dominated the processing stages of both condiments. Although no single OTU occurred throughout iru processing stages, an OTU (mostly related to B. safensis) dominated the ogiri processing stages indicating potentials for the development of starter culture. However, other isolates such as those of Enterococcus spp. and Lysinibacillus spp. may be potential starters for iru fermentation. Presumptive food-borne pathogens were also detected at some stages of the condiments' processing, possibly due to poor hygienic practices. SIGNIFICANCE AND IMPACT OF THE STUDY: Iru and ogiri are important condiments used for flavour enhancement in foods and serve as protein substitutes in diets among rural populations across West Africa. Consumption of these condiments is growing, reinforcing the need to scale up their production. Production of these condiments includes spontaneous fermentation, which often leads to inconsistent product quality and unguaranteed safety. This study has demonstrated the bacterial succession in iru and ogiri processing and highlights species that could be selected and exploited for starter culture development. This study provides a starting point to produce quality and microbiologically safe iru and ogiri condiments.

Rapid screening of starter cultures for maari based on antifungal properties.

Forty Bacillus isolates obtained from maari (used as condiment in Burkina Faso) including 17 B. subtilis, 4 B. circulans, 7 B. pumilus and 6 B. licheniformis were investigated for use as starter cultures in maari production. The isolates were screened by PCR for the sfp gene responsible for the production of the lipopeptide biosurfactant, surfactin. The sfp gene was detected in all of the seventeen B. subtilis isolates, in 2 out of 7 B. pumilus, in 4 out of 6 B. licheniformis whereas no B. circulans was positive for the sfp gene by PCR screening. Furthermore, all the 40 Bacillus spp. were screened for biosurfactant production and inhibitory activity against Aspergillus flavus, A. niger, A. versicolor and Rhizopus oryzae. Results demonstrated a relationship between the presence of the sfp gene and the antifungal activity and biosurfactant production of Bacillus isolates. In addition, molecular typing of the 17 B. subtilis isolates by Multilocus Sequence Typing (MLST) resulted in 15 Sequence Types, one of them included three strains. Randomly Amplified Polymorphic DNA-PCR (RAPD-PCR), used for B. licheniformis, B. megaterium, B. circulans and B. pumilus revealed that the inhibitory activity and biosurfactant production were strain-dependent. Finally, the detection of chitinase (chi) and ß-glucanase (glu) biosynthesis genes was found to be associated with the antifungal activity for 16 B. subtilis isolates. The present work provides a greater understanding of the antifungal activity and biosurfactant production ability within the Bacillus spp. isolated from maari and contributes to the selection of Bacillus isolates to be used as starter cultures for controlled production of maari.

Comparison of Antiobesity Effects Between Gochujangs Produced Using Different Koji Products and Tabasco Hot Sauce in Rats Fed a High-Fat Diet.

In this study, we compared the antiobesity effects between gochujangs prepared using different koji products and Tabasco hot sauce in rats fed a high-fat diet (HFD). Male Sprague-Dawley rats were fed HFD containing four different types of 10% gochujang powder or 0.25% commercial Tabasco sauce powder for 8 weeks. The body weight gain, liver and epididymal and mesenteric fat pad weights, serum leptin levels, and lipogenesis-related mRNA levels of HFD-gochujang supplementation groups were significantly decreased compared with those of the HFD group. In addition, gochujang supplement significantly reduced adipocyte size; hepatic triglyceride and total cholesterol levels; the occurrence of fatty liver deposits and steatosis by inhibiting lipogenesis through downregulation of fatty acid synthase, acetly-CoA carboxylase, and glucose-6-phosphate-dehydrogenase. These effects were greater in the gochujang-supplemented groups than the Tabasco hot sauce-supplemented group. The gochujang prepared by nutritious giant embryo rice koji and soybean koji was most effective in terms of antiobesity effects, compared with the other tested gochujangs. In gochujangs, the antiobesity effects are mediated by high levels of secondary metabolites such as isoflavone, soyasaponin, capsaicin, and lysophosphatidylcholine. The current results indicated that the gochujang products have the potential to reduce fat accumulation and obesity.

Bacterial species and mycotoxin contamination associated with locust bean, melon and their fermented products in south-western Nigeria.

The microbiological safety of spontaneously fermented foods is not always guaranteed due to the undefined fermenting microbial consortium and processing materials. In this study, two commonly consumed traditional condiments (iru and ogiri) and their respective raw seeds (locust bean and melon) purchased from markets in south-western Nigeria were assessed for bacterial diversity and mycotoxin contamination using 16S rRNA gene sequencing and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. Two hundred isolates obtained from the raw seeds and condiments clustered into 10 operational taxonomic units (OTUs) and spanned 3 phyla, 10 genera, 14 species and 2 sub-species. Bacillus (25%) and Staphylococcus (23.5%) dominated other genera. Potentially pathogenic species such as Alcaligenes faecalis, Bacillus anthracis, Proteus mirabilis and Staphylococcus sciuri subsp. sciuri occurred in the samples, suggesting poor hygienic practice during production and/or handling of the condiments. A total of 48 microbial metabolites including 7 mycotoxins [3-nitropropionic acid, aflatoxin B1 (AFB1), AFB2, beauvericin, citrinin, ochratoxin A and sterigmatocystin] were quantified in the food samples. Melon and ogiri had detectable aflatoxin levels whereas locust bean and iru did not; the overall mycotoxin levels in the food samples were low. There is a need to educate processors/vendors of these condiments on good hygienic and processing practices.

Physio-chemical, microbiological properties of tempoyak and molecular characterisation of lactic acid bacteria isolated from tempoyak.

This study aims to determine physio-chemical properties of tempoyak, characterise the various indigenous species of lactic acid bacteria (LAB) present at different stages of fermentation and also to determine the survival of selected foodborne pathogens in tempoyak. The predominant microorganisms present in tempoyak were LAB (8.88-10.42 log CFU/g). Fructobacillus durionis and Lactobacillus plantarum were the dominant members of LAB. Other LAB species detected for the first time in tempoyak were a fructophilic strain of Lactobacillus fructivorans, Leuconostoc dextranicum, Lactobacillus collinoides and Lactobacillus paracasei. Heterofermentative Leuconostoc mesenteroides and F. durionis were predominant in the initial stage of fermentation, and as fermentation proceeded, F. durionis remained predominant, but towards the end of fermentation, homofermentative Lb. plantarum became the predominant species. Lactic, acetic and propionic acids were present in concentrations ranging from 0.30 to 9.65, 0.51 to 7.14 and 3.90 to 7.31 mg/g, respectively. Genotyping showed a high degree of diversity among F. durionis and Lb. plantarum isolates, suggesting different sources of LAB. All tested Lb. plantarum and F. durionis (except for one isolate) isolates were multidrug resistant. Salmonella spp., Listeria monocytogenes and Staphylococcus aureus were not detected. However, survival study showed that these pathogens could survive up to 8-12 days. The results aiming at improving the quality and safety of tempoyak.

Modeling Growth Kinetic Parameters of Salmonella Enteritidis SE86 on Homemade Mayonnaise Under Isothermal and Nonisothermal Conditions.

During the last decade, a specific strain of Salmonella Enteritidis (named SE86) has been identified as the major etiological agent responsible for salmonellosis in the State of Rio Grande do Sul, Southern Brazil, and the main food vehicle was homemade mayonnaise (HM). This study aimed to model the growth prediction of SE86 on HM under isothermal and nonisothermal conditions. SE86 was inoculated on HM and stored at 7, 10, 15, 20, 25, 30, and 37°C. Growth curves were built by fitting data to the Baranyi's DMFit, generating r(2) values greater than 0.98 for primary models. Secondary model was fitted with Ratkowsky equation, generating r(2) and root mean square error values of 0.99 and 0.016, respectively. Also, the growth of SE86 under nonisothermal conditions simulating abuse temperature during preparation, storage, and serving of HM was studied. Experimental data showed that SE86 did not grow on HM at 7°C for 30 days. At 10°C, no growth was observed until approximately 18 h, and the infective dose (assumed as 10(6) CFU/g) was reached after 8.1 days. However, the same numbers of SE86 were attained after 6 hours at 37°C. Experimental data demonstrated shorter lag times than those generated by ComBase Predictive Models, suggesting that SE86 is very well adapted for growing on HM. SE86 stored under nonisothermal conditions increased population to reach about 10(6) CFU/g after approximately 30 hours of storage. In conclusion, the developed model can be used to predict the growth of SE86 on HM under various temperatures, and considering this pathogen, HM can be produced if safe eggs are used and HM is stored below 7°C.

PCR-denaturing gradient gel electrophoresis analysis of microbial community in soy-daddawa, a Nigerian fermented soybean (Glycine max (L.) Merr.) condiment.

Soy-daddawa, a fermented soybean (Glycine max (L.) Merr.) condiment, plays a significant role in the culinary practice of West Africa. It is essential to understand the microbial community of soy-daddawa for a successful starter culture application. This study investigated the microbial community structure of soy-daddawa samples collected from Nigerian markets, by PCR-denaturing gradient gel electrophoresis (DGGE) targeting the V3-V5 region of the 16S rRNA gene of bacteria and internal transcribed spacer 2 (ITS2) region of fungi. Six bacterial and 16 fungal (nine yeasts and seven molds) operational taxonomic units (OTUs)/species were obtained at 97% sequence similarity. Taxonomic assignments revealed that bacterial OTUs belonged to the phyla Firmicutes and Actinobacteria, and included species from the genera Atopostipes, Bacillus, Brevibacterium and Nosocomiicoccus. Densitometric analysis of DGGE image/bands revealed that Bacillus spp. were the dominant OTU/species in terms of population numbers. Fungal OTUs belonged to the phyla Ascomycota and Zygomycota, and included species from the genera, Alternaria, Aspergillus, Candida, Cladosporium, Dokmaia, Issatchenkia, Kodamaea, Lecythophora, Phoma, Pichia, Rhizopus, Saccharomyces and Starmerella. The majority of fungal species have not been previously reported in soy-daddawa. Potential opportunistic human pathogens such as Atopostipes suicloacalis, Candida rugosa, Candida tropicalis, and Kodamaea ohmeri were detected. Variation in soy-daddawa microbial communities amongst samples and presence of potential opportunistic pathogens emphasises the need for starter culture employment and good handling practices in soy-daddawa processing.