The dominant microbial community associated with fermentation of Obushera (sorghum and millet beverages) determined by culture-dependent and culture-independent methods

Clavispora lusitaniae: From a saprophytic yeast to an emergent pathogen

Clavispora lusitaniae has been isolated from different substrates, such as soil, water, fruit, vegetables, plants, and the gastrointestinal tract of animals and humans. However, its importance lies in being isolated from in invasive infections, particularly in pediatric patients with hematologic malignancies. It is an emerging nosocomial pathogen commonly associated with fatal prognosis in immunocompromised hosts. C. lusitaniae has attracted attention in the last decade because of resistance to amphotericin B, 5- flucytosine, and fluconazole. The adaptations of this yeast to the human host may contribute to its pathogenicity. Further study will be needed to understand C. lusitaniae's ability as a potential pathogen. This mini-review highlights the importance of the growing number of invasive disease cases caused by this yeast.

The predominant lactic acid bacteria and yeasts involved in the spontaneous fermentation of millet during the production of the traditional porridge Hausa koko in Ghana

Spontaneous fermentation of cereals like millet involves a diverse population of microbes from various sources, including raw materials, processing equipment, fermenting receptacles, and the environment. Here, we present data on the predominant microbial species and their succession at each stage of the Hausa koko production process from five regions of Ghana. The isolates were enumerated using selective media, purified, and phenotypically characterised. The LAB isolates were further characterised by 16S rRNA Sanger sequencing, typed using (GTG)5 repetitive-PCR, and whole genome sequencing, while 28S rRNA Sanger sequencing was performed for yeast identification. The pH of the millet grains ranged from mean values of 6.02-6.53 to 3.51-3.99 in the final product, depending on the processors. The mean LAB and yeast counts increased during fermentation then fell to final counts of log 2.77-3.95 CFU/g for LAB and log 2.10-2.98 CFU/g for yeast in Hausa koko samples. At the various processing stages, the counts of LAB and yeast revealed significant variations (p < 0.0001). The species of LAB identified in this study were Limosilactobacillus pontis, Pediococcus acidilactici, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Pediococcus pentosaceus, Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Schleiferilactobacillus harbinensis, and Weissella confusa. The yeasts were Saccharomyces cf. cerevisiae/paradoxus, Saccharomyces cerevisiae, Pichia kudriavzevii, Clavispora lusitaniae and Candida tropicalis. The identification and sequencing of these novel isolates and how they change during the fermentation process will pave the way for future controlled fermentation, safer starter cultures, and identifying optimal stages for starter culture addition or nutritional interventions. These LAB and yeast species are linked to many indigenous African fermented foods, potentially acting as probiotics in some cases. This result serves as the basis for further studies into the technological and probiotic potential of these Hausa koko microorganisms.

Microbial Diversity in African Foods and Beverages: A Systematic Assessment

This article provides a comprehensive and in-depth examination of the microbial diversity inherent in African food and beverages, with a particular emphasis on fermented products. It identifies and characterizes the dominant microorganisms, including both prokaryotes and yeasts, prevalent in these foods, and furthermore, critically analyzes the health benefits of these microbial strains, especially their probiotic properties, which could potentially improve digestion and contribute to human health. Notably, it underscores the vital role these microorganisms play in bolstering food security across Africa by enhancing and preserving food quality and safety. It also delves into the potential applications of microbial products, such as metabolites, in the food industry, suggesting their possible use in food processing and preservation. Conclusively, with a summarization of the key findings, emphasizing the importance of gaining a deep understanding of microbial diversity in African beverages and foods. Such knowledge is crucial not only in promoting food security but also in advancing public health.

Analysis of the bacterial and fungal populations in South African sorghum beer (umqombothi) using full-length 16S rRNA amplicon sequencing

There is a need to profile microorganisms which exist pre-and-post-production of umqombothi, to understand its microbial diversity and the interactions which subsequently influence the final product. Thus, this study sought to determine the relative microbial abundance in umqombothi and predict the functional pathways of bacterial and fungal microbiota present. Full-length bacterial 16S rRNA and internal transcribed spacer (ITS) gene sequencing using PacBio single-molecule, real-time (SMRT) technology was used to assess the microbial compositions. PICRUSt2 was adopted to infer microbial functional differences. A mixture of harmful and beneficial microorganisms was observed in all samples. The microbial diversity differed significantly between the mixed raw ingredients (MRI), customary beer brew (CB), and optimised beer brew (OPB). The highest bacterial species diversity was observed in the MRI, while the highest fungal species diversity was observed in the OPB. The dominant bacterial species in the MRI, CB, and OPB were Kosakonia cowanii, Apilactobacillus pseudoficulneus, and Vibrio alginolyticus, respectively, while the dominant fungal species was Apiotrichum laibachii. The predicted functional annotations revealed significant (p < 0.05) differences in the microbial pathways of the fermented and unfermented samples. The most abundant pathways in the MRI were the branched-chain amino acid biosynthesis super pathway and the pentose phosphate pathway. The CB sample was characterised by folate (vitamin B9) transformations III, and mixed acid fermentation. Biotin (vitamin B7) biosynthesis I and L-valine biosynthesis characterised the OPB sample. These findings can assist in identifying potential starter cultures for the commercial production of umqombothi. Specifically, A. pseudoficulneus can be used for controlled fermentation during the production of umqombothi. Likewise, the use of A. laibachii can allow for better control over the fermentation kinetics such as carbohydrate conversion and end-product characteristics, especially esters and aroma compounds.

African cereal fermentations: A review on fermentation processes and microbial composition of non-alcoholic fermented cereal foods and beverages

Africa has a rich tradition of cereal fermentations to produce diverse products including baked goods, porridges, non-alcoholic beverages and alcoholic beverages. Diversity also relates to the choice of the fermentation substrates, which include wheat, maize, teff, sorghum and millet, and the fermentation processes that are used in food production. For fermentation processes that are used in baking and brewing, it is well established that the composition of fermentation microbiota and thus the impact of fermentation on product quality is determined by the choice of fermentation conditions. This link has not been systematically explored for African cereal fermentations. This review therefore aims to provide an overview on the diversity of African fermented cereal products, and to interrogate currently available literature data with respect to the impact of fermentation substrate and fermentation processes on the assembly of fermentation microorganisms and product quality.

The periodic table of fermented foods: limitations and opportunities

Fermentation is one of the oldest methods of food processing and accounts for a substantial proportion of human foods, including not only staple foods such as bread, cereal porridges or fermented legumes but also fermented vegetables, meats, fish and dairy, alcoholic beverages as well as coffee, cocoa and condiments such as vinegar, soy sauce and fish sauces. Adding the regional varieties to these diverse product categories makes for an almost immeasurable diversity of fermented foods. The periodic table of fermented foods aims to map this diversity on the 118 entries of the periodic table of chemical elements. While the table fails to represent the diversity of fermented foods, it represents major fermentation substrates, product categories, fermentation processes and fermentation organisms. This communication not only addresses limitations of the graphical display on a "periodic table of fermented foods", but also identifies opportunities that relate to questions that are facilitated by this graphical presentation: on the origin and purpose of food fermentation, which fermented foods represent "indigenous" foods, differences and similarities in the assembly of microbial communities in different fermentations, differences in the global preferences for food fermentation, the link between microbial diversity, fermentation time and product properties, and opportunities of using traditional food fermentations as template for development of new products. KEY POINTS: • Fermented foods are produced in an almost immeasurable diversity. • Fermented foods were mapped on a periodic table of fermented foods. • This table facilitates identification of communalities and differences of products.

Co-occurrence of Lactobacillus Species During Fermentation of African Indigenous Foods: Impact on Food Safety and Shelf-Life Extension

The benefits derived from fermented foods and beverages have placed great value on their acceptability worldwide. Food fermentation technologies have been employed for thousands of years and are considered essential processes for the production and preservation of foods, with the critical roles played by the autochthonous fermenting food-grade microorganisms in ensuring food security and safety, increased shelf life, and enhanced livelihoods of many people in Africa, particularly the marginalized and vulnerable groups. Many indigenous fermented foods and beverages of Africa are of plant origin. In this review, the predominance, fermentative activities, and biopreservative role of Lactobacillus spp. during production of indigenous foods and beverages, the potential health benefit of probiotics, and the impact of these food-grade microorganisms on food safety and prolonged shelf life are discussed. During production of African indigenous foods (with emphasis on cereals and cassava-based food products), fermentation occurs in succession; the first group of microorganisms to colonize the fermenting substrates are lactic acid bacteria (LAB) with the diversity and dominance of Lactobacillus spp. The Lactobacillus spp. multiply rapidly in the fermentation matrix, by taking up nutrients from the surrounding environments, and cause rapid acidification in the fermenting system via the production of organic compounds that convert fermentable sugars into mainly lactic acid. Production of these compounds in food systems inhibits spoilage microorganisms, which has a direct effect on food quality and safety. The knowledge of microbial interaction and succession during food fermentation will assist the food industry in producing functional foods and beverages with improved nutritional profiling and technological attributes, as Lactobacillus strains isolated during fermentation of several African indigenous foods have demonstrated desirable characteristics that make them safe for use as probiotic microorganisms and even as a starter culture in small- and large-scale/industrial food production processes.

Acid stress responses of Lactobacillus amylovorus and Candida kefyr isolated from fermented sorghum gruel and their application in food fermentation

Exposure of Lactic Acid Bacteria (LAB) and yeasts to adverse fluctuations during fermentation causes stress, consequently, microbes develop adaptive responses. In this study, the physiological and proteomic responses of LAB and yeast to acid stress, and their application in food fermentation was investigated. The physiological and proteomic responses of Lactobacillus amylovorus LS07 and Candida kefyr YS12 to acid stress were measured using turbidimetry method, SDS-PAGE and LC-MS/MS respectively. The technique previously reported by Association of Official Analytical Chemists (AOAC) were employed for evaluation of the physiocochemical and organoleptic properties of the sorghum gruel fermented using the LAB and yeast in singly and combination as starter cultures and spontaneous fermentation as control. Growth of L. amylovorus LS07 was optimal at pH 1.0 and C. kefyr YSI2 at pH 4. An increased intensity of 30S ribosomal protein S2 (L. amylovorus LS07) and 6-phosphogluconate dehydrogenase (C. kefyr YS12) was noted at pH 1 and 4 respectively suggesting increased microbial metabolism thereby reducing stress encountered. Sorghum gruel produced with combined starters had the highest crude protein (10.94 %), Iron content (0.0085 %), organoleptic acceptability (7.29) significantly different from products produced with the single starters and control. The combined starter's (L. amylovorus LS07 and C. kefyr YSI2 as starter) adapted stress yielded foods with improved sensory properties, mineral and reduced anti-nutrient contents.

Microbial community shifts association with physicochemical parameters: Visualizing enset bacterial wilt from different states of enset health

Bacterial wilt of enset caused by Xanthomonas campestris is a devastating disease in Ethiopia, where enset is domesticated and served as a staple food for about 20 million people in the country. While enset is infected by bacteria, it shows different wilting stages. However, the microbial community shifts at the different stages of enset infection and associated physicochemical parameter changes remain poorly understood. This study was aimed to visualize the proportion of enset wilt bacterium from other microbial community and its association with physicochemical parameter at different states of enset health. Soil and enset (zero, first, second and third stages) samples were collected from three districts in Gamo Highlands for physicochemical and biological (culture dependent and16S rRNA gene sequence) analysis. The results of culture dependent analysis which has been complemented by 16S rRNA gene sequence confirmed that increasing trends were observed for Xanthomonadaceae, Pseudomonadaceae, Lactobacillaceae and Flavobacteriaceae, while Bacillaceae and Enterobacteriaceae showed progressive decrease from zero to the third stage. Particularly, the 16S rRNA data showed that Xanthomonadaceae increased significantly from zero to different (2.5 × 10² times at the onset of disease and 1.0-2.0 × 10⁴ times at the second and third) stages of enset infection. Most physicochemical results showed that a decreasing trends from zero to third stage, while few parameters are showing an increasing trend. Moisture content (R² ≥ 0.951, P ≤ 0.049) of the soil and plant samples positively influenced Xanthomonas abundance, while this bacterium showed a strongly negative significant correlation with pH (R² ≥ -0.962, P ≤ 0.038), temperature (R² ≥ -0.958, P ≤ 0.042), OM (R² ≥ -0.952, P ≤ 0.048), and TN (R² ≥ -0.951, P ≤ 0.049). A strongly negative significant correlation (R² ≥ -0.948, P ≤ 0.050) was also observed between Xanthomonas and nutrients (K, Mg, Ca, and Cu). Overall, this study implies that different environmental factors found a key driving force of Xanthomonas proportional increment from low abundance at zero stage to higher abundance at the last stage of enset infection suggesting that considering these factors help to design an effective enset disease management strategy, for which further studies will be needed.

Apple Pomace as a Sustainable Substrate in Sourdough Fermentation

Innovations range from food production, land use, and emissions all the way to improved diets and waste management. Global apple production has amounted to over 87 million tons/year, while 18% are processed, resulting in 20-35% (apple fruit fresh weight) apple pomace (AP). Using modern AP management, integrated knowledge in innovative fermentation demonstrates opportunities for reducing environmental pollution and integration into a circular economy. With this association in view, integrating AP flour during sourdough fermentation increases the nutritional value, highlighting a new approach that could guide innovative fermented foods. In this study, the wheat flour (WF) and AP flour were mixed at different ratios, hydrated with water (1:1 w/v), and fermented using a selective culture of Fructilactobacillus florum DSM 22689 and baker's yeast (single and co-culture). Sourdough fermentation was monitored and analyzed for 72 h. Results suggested that AP may be an important source of organic acids and fermentable sugars that increase nutritional sourdough value. AP flour addition in WF had a positive effect, especially in fermentations with 95% WF and 5% AP, mainly in co-culture fermentation.

Sorghum Malt Extract as a Growth Medium for Lactic Acid Bacteria Cultures: A Case of Lactobacillus plantarum MNC 21

Cultivation of lactic acid bacteria cultures is vital for research and commercial production of fermented foods. However, the conventional growth media used are generally costly. Malt extracts from four sorghum varieties (SESO 1, SESO 3, Epuripur, and Eyera) were evaluated as alternative low-cost growth media for Lactobacillus plantarum MNC 21. Saccharified sorghum malt extracts were inoculated with 4 log cfu/mL MNC 21 and incubated at 30°C for 24 h. MRS broth was the reference medium. Microbial counts, pH, titratable acidity (TA), free amino nitrogen (FAN), and total sugars were measured. Maximum microbial counts in the extracts and MRS broth were 9 and 10 log cfu/mL, respectively. Maximum growth rate in the extracts was 0.7-0.9 log cfu/mL/h and 0.8 log cfu/mL/h in MRS broth. The final pH of the extracts was 3.5-3.6, with an overall increase in TA of 1.2% in Epuripur and 0.2% in other varieties. Final pH and TA of MRS broth were 4.1 and 1.3%, respectively. Total sugars dropped by 95.2% and FAN by 2.1% in MRS broth. In contrast, total sugars and FAN dropped by 5.6-9.1% and 24.9-32.7% respectively, in the extracts. Sorghum malt extracts can be adopted as alternative low-cost growth media for lactic acid bacteria cultures.

A Comparative Interrupted Times Series on the Health Impact of Probiotic Yogurt Consumption Among School Children From Three to Six Years Old in Southwest Uganda

Introduction: Following a school milk feeding program in Southwest Uganda, we initiated a probiotic yogurt school feeding program in the same region in 2018. In order to investigate the potential health benefits from probiotic yogurt we conducted an observational study, where we compared the effect of the consumption of locally produced probiotic yogurt containing Lactobacillus rhamnosus yoba 2012 to milk in pre-primary schoolchildren from different schools on the occurrence of respiratory tract infections (common cold) and skin infections (e.g., tinea capitis). Method: A comparative interrupted time series over a period of 3 weeks of baseline followed by 9 weeks of 100 ml of probiotic yogurt or milk consumption for 5 days per week. In total 584 children attending five different schools were followed during consumption of probiotic yogurt and 532 children attending five other schools during consumption of milk. Incidences of respiratory tract infection symptoms and skin infection symptoms, changes in anthropometric indicators and absenteeism were recorded. Results: Over the course of the study period the incidence rate for common cold symptoms decreased faster in the yogurt group than in the milk group (p = 0.09) resulting in a final RR of 0.85 (95% CI: 0.5-1.4) at the end of the observational period. The incidence rate of skin infection related symptoms also reduced faster in the yogurt group compared to the milk group (p < 0.0001) resulting in a relative risk factor (RR) of 0.6 (CI: 0.4-0.9) at the end of the observational period. Anthropometric indicators and level of absenteeism did not show significant differences between yogurt and milk. Conclusion: Notwithstanding the observed positive trend and effect of probiotic yogurt on the incidences of common cold and skin infections, respectively, we consider the results of this comparative interrupted time series inconclusive due to differences in the recorded health parameters between the probiotic yogurt and milk control groups at base line, and fluctuations over the course of the intervention period. An improved study design, with more uniform study groups, a longer intervention period and a third control group without yogurt or milk is required to draw definitive conclusions.

Probiotic Potential of Lactic Acid Starter Cultures Isolated from a Traditional Fermented Sorghum-Millet Beverage

The purpose of this study was to establish the probiotic potential of lactic acid bacteria (LAB) starter cultures, Lb. plantarum MNC 21, L. lactis MNC 24, and W. confusa MNC 20, isolated from a traditionally fermented sorghum-millet beverage from Uganda. The cultures were examined for tolerance to acid and bile salts, bile salt hydrolase (BSH) activity, antibiotic susceptibility, biogenic amine production, mucin degradation, hydrophobicity, auto-aggregation, adherence to the ileum, coaggregation, and antimicrobial properties against selected pathogenic species. Lb. rhamnosus yoba 2012, a known probiotic, was the reference. The isolates were tolerant to acid (pH = 3) and bile (1%). W. confusa MNC 20 and Lb. plantarum MNC 21 exhibited medium BSH activity (11-15 mm diameter of hydrolysis zone) while L. lactis and Lb. rhamnosus yoba 2012 exhibited low BSH activity (<10 mm diameter of hydrolysis zone). All isolates lacked mucolytic activity. Lb. plantarum MNC 21 and W. confusa MNC 20 produced agmatine. The candidate and reference microorganisms were resistant to 10 of 21 and 5 of 21 antibiotics, respectively. The isolates exhibited hydrophobic, auto-aggregation and coaggregation properties. These three properties were exhibited more (p < 0.05) by the reference than the potential probiotics. The ability of the potential probiotics to attach onto the goat ileum (7.3-8.0 log cfu/cm²) was comparable to that of Lb. rhamnosus yoba 2012 (7.6 log cfu/cm²). The four LAB inhibited E. coli, S. aureus, and S. enterica to the same extent (p < 0.05). The findings indicated potential probiotic activity of the starter cultures. However, further in vivo examination of these isolates is required to confirm their probiotic capabilities.

Tolerance to acid and alkali by Streptococcus infantarius subsp. infantarius strain 25124 isolated from fermented nixtamal dough: Pozol. Studies in APT broth

Pozol is a beverage prepared with maize dough made after boiling the kernels in limewater. This pretreatment could act as a selective force that shapes the starter microbiota, with microorganisms able to survive the fermentation. Since Streptococcus infantarius subsp. infantarius (Sii) dominates in pozol, we evaluated the effect of acid and alkali stresses on strain Sii-25124 in commercial APT broth as a first attempt to assess its adaptation capacity. Results suggest that Sii-25124 has adaptative advantages to pH changes that possibly contribute to its persistence even after the acidification of the dough. Its cardinal pH values were 4.0 and 11.0, with an optimum between 6.6 and 8.0. It showed alkali tolerance unlike other pozol Sii strains. Adaptation at pH 4.0, 10.0 and 11.0, compared with non-adapted cells, induced acid tolerance enhancing survival at pH 3.6 (P < 0.05); a 2 min heat shock at 62 °C induced alkali tolerance response enhancing survival at pH 10.5 (P < 0.05). The up-regulation of dnaK, groEL, ptsG and atpB was observed during 5 h of exposition at pH 3.6, 4.0 and 10.0, showing similar expression rates after induction by acid shock or alkaline stress. Changes of atpB were more evident having almost five-fold induction during long-term stress.

Antimicrobial Activity of Lactic Acid Bacteria Starters against Acid Tolerant, Antibiotic Resistant, and Potentially Virulent E. coli Isolated from a Fermented Sorghum-Millet Beverage

Bacterial contamination of fermented foods is a serious global food safety challenge that requires effective control strategies. This study characterized presumptive E. coli isolated from Obushera, a traditional fermented cereal beverage from Uganda. Thereafter, the antimicrobial effect of lactic acid bacteria (LAB) previously isolated from Obushera, against the E. coli, was examined. The presumptive E. coli was incubated in brain heart infusion broth (pH = 3.6) at 25°C for 48 h. The most acid-stable strains were clustered using (GTG)5 rep-PCR fingerprinting and identified using 16S rRNA sequencing. E. coli was screened for Shiga toxins (Stx 1 and Stx 2) and Intimin (eae) virulence genes as well as antibiotic resistance. The spot-on-the-lawn method was used to evaluate antimicrobial activity. Eighteen isolates were acid stable and are identified as E. coli, Shigella, and Lysinibacillus. The Stx 2 gene and antibiotic resistance were detected in some E. coli isolates. The LAB were antagonistic against the E. coli. Lactic acid bacteria from traditional fermented foods can be applied in food processing to inhibit pathogens. Obushera lactic acid bacteria could be used to improve the safety of fermented foods.

Comparison of the microbial composition of African fermented foods using amplicon sequencing

Fermented foods play a major role in the diet of people in Africa, where a wide variety of raw materials are fermented. Understanding the microbial populations of these products would help in the design of specific starter cultures to produce standardized and safer foods. In this study, the bacterial diversity of African fermented foods produced from several raw materials (cereals, milk, cassava, honey, palm sap, and locust beans) under different conditions (household, small commercial producers or laboratory) in 8 African countries was analysed by 16S rRNA gene amplicon sequencing during the Workshop "Analysis of the Microbiomes of Naturally Fermented Foods Training Course". Results show that lactobacilli were less abundant in fermentations performed under laboratory conditions compared to artisanal or commercial fermentations. Excluding the samples produced under laboratory conditions, lactobacilli is one of the dominant groups in all the remaining samples. Genera within the order Lactobacillales dominated dairy, cereal and cassava fermentations. Genera within the order Lactobacillales, and genera Zymomonas and Bacillus were predominant in alcoholic beverages, whereas Bacillus and Lactobacillus were the dominant genera in the locust bean sample. The genus Zymomonas was reported for the first time in dairy, cereal, cassava and locust bean fermentations.

Occurrence and Importance of Yeasts in Indigenous Fermented Food and Beverages Produced in Sub-Saharan Africa

Indigenous fermented food and beverages represent a valuable cultural heritage in sub-Saharan Africa, having one of the richest selections of fermented food products in the world. In many of these indigenous spontaneously fermented food and beverages, yeasts are of significant importance. Several factors including raw materials, processing methods, hygienic conditions as well as the interactions between yeasts and other commensal microorganisms have been shown to influence yeast species diversity and successions. Both at species and strain levels, successions take place due to the continuous change in intrinsic and extrinsic growth factors. The selection pressure from the microbial stress factors leads to niche adaptation and both yeast species and strains with traits deviating from those generally acknowledged in current taxonomic keys, have been isolated from indigenous sub-Saharan African fermented food products. Yeasts are important for flavor development, impact shelf life, and nutritional value and do, in some cases, even provide host-beneficial effects. In order to sustain and upgrade these traditional fermented products, it is quite important to obtain detailed knowledge on the microorganisms involved in the fermentations, their growth requirements and interactions. While other publications have reported on the occurrence of prokaryotes in spontaneously fermented sub-Saharan food and beverages, the present review focuses on yeasts considering their current taxonomic position, relative occurrence and successions, interactions with other commensal microorganisms as well as beneficial effects and importance in human diet. Additionally, the risk of opportunistic yeasts is discussed.

Fructose-rich niches traced the evolution of lactic acid bacteria toward fructophilic species

Fructophilic lactic acid bacteria (FLAB) are found in fructose-rich habitats associated with flowers, fruits, fermented foods, and the gastrointestinal tract of several insects having a fructose-based diet. FLAB are heterofermentative lactobacilli that prefer fructose instead of glucose as carbon source, although additional electron acceptor substrates (e.g. oxygen) remarkably enhance their growth on glucose. As a newly discovered bacterial group, FLAB are gaining increasing interest. In this review, the ecological context in which these bacteria exist and evolve was resumed. The wide frequency of isolation of FLAB from fructose feeding insects has been deepened to reveal their ecological significance. Genomic, metabolic data, reductive evolution, and niche specialization of the main FLAB species have been discussed. Findings to date acquired are consistent with a metabolic model in which FLAB display a reliance on environmental niches and the degree of host specificity. In light of FLAB proximity to lactic acid bacteria generally considered to be safe, and due to their peculiar metabolic traits, FLAB may be successfully exploited in food and pharmaceutical applications.

Encapsulation of erythromycin and bacitracin antibiotics into natural sporopollenin microcapsules: antibacterial, cytotoxicity, in vitro and in vivo release studies for enhanced bioavailability

Nature produces large quantities of superbly complex and highly reliable microcapsules. The micrometre-sized Lycopodium clavatum spores are one example of these robust capsules. The encapsulation of erythromycin (EM) and bacitracin (BAC) antibiotics into the Lycopodium clavatum sporopollenin (LCS) extracted from these spore species is explored for the first time. The LCS microparticles are extensively characterised before and after loading using SEM, CLSM, TGA and FTIR techniques. The loading capacity and entrapping efficiency of EM were 16.2 and 32.4%, respectively. The antibacterial activities of pure antibiotics, empty LCS and the antibiotic-loaded LCS were evaluated against Staphylococcus aureus (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Klebsiella pneumoniae (Gram-negative) human pathogenic bacterial strains. A remarkable increase in the antibacterial fold activity of both EM- and BAC-loaded LCS compared to that of the pure antibiotics is observed. Crucial for drug delivery applications, empty LCS, EM- and BAC-loaded LCS were found to be nontoxic against human epithelial colorectal adenocarcinoma cells Caco-2 as revealed by the cytotoxicity evaluation. The in vitro release mechanism of EM in pH 7.4 showed a deviation from Fick's law. In vivo release of EM from EM-loaded LCS (an oral dose of 50 mg kg-1) revealed high values of the area under the plasma concentration-time curve (AUC0-6 h and AUC0-∞ were 1620 and 2147 μg h L-1, respectively) indicative of the enhanced EM bioavailability. The successful loading of antibiotics into the nontoxic LCS and the enhanced bioavailability can open up intriguing applications in oral and topical drug delivery strategies.

Fitness of Jiaozi starter for steamed bread production using a two-stage procedure

Steamed bread is a popular staple food in China. Jiaozi shows many advantages as a starter for dough fermentation and is frequently used for steamed bread production. The knowledge about the dough fermentation process using Jiaozi is helpful for production management and quality improvement of the final product. In this study, the applicability of Jiaozi for steamed bread production was investigated. Some important factors involved in dough fermentation were carefully examined and analyzed, including the evolution and diversity of major bacteria and fungi, acidity change, reducing sugar utilization, CO 2 production and retention, and different full dough fermentation periods. Combined with the quality evaluation of the final product, the results displayed that traditional Jiaozi was suitable as starter for steamed bread production using a two-stage procedure with a wide range of full fermentation time and also provided more insights into steamed bread production by Jiaozi.

Molecular Identification of Yeasts and Lactic Acid Bacteria Involved in the Production of Beninese Fermented Food Degue

Background:

Traditional Beninese fermented food Degue is widely consumed in Benin and other countries in West Africa. It was originally made from milk and millet flour, but currently other cereals are used as well. Nowadays, Degue production occurs by spontaneous fermentation in individual households and information about the microorganisms involved is currently limited.

Objective:

The microbiota of Degue from Benin has not been studied so far, but its growing production in the country sets a demand for revealing the biodiversity of the microbial population involved in the fermentation process in order to take future steps for development of industrial technology and offer products with improved quality and safety.

Method:

In the present study, yeast and lactic acid bacteria from raw materials for Degue production and from several Degue products were isolated and identified by molecular methods including RFLP and ITS1-5.8S-ITS2 rRNA gene sequence analysis in yeasts, and 16S rRNA gene sequence analysis in lactic acid bacteria.

Results:

Lactic acid bacteria isolates were assigned to eight species within the generaLactobacillus,Enterococcus,Pediococcus,StreptococcusandWeisella. Four species of yeasts were found in Degue:Cyberlyndnera fabianii,Candida glabrata,Kluyveromyces marxianus, andMeyerozyma caribbica.

Conclusion:

The microbial population revealed is unique to Beninese Degue and needs further characterization for development of defined starter cultures.

Genome Sequences of Cyberlindnera fabianii 65, Pichia kudriavzevii 129, and Saccharomyces cerevisiae 131 Isolated from Fermented Masau Fruits in Zimbabwe

Cyberlindnera fabianii 65, Pichia kudriavzevii 129, and Saccharomyces cerevisiae 131 have been isolated from the microbiota of fermented masau fruits. C. fabianii and P. kudriavzevii especially harbor promising features for biotechnology and food applications. Here, we present the draft annotated genome sequences of these isolates.

Production of organic flavor compounds by dominant lactic acid bacteria and yeasts from Obushera, a traditional sorghum malt fermented beverage

Single and mixed starter cultures of lactic acid bacteria (LAB): Weissella confusa MNC20, Lactobacillus plantarum MNC21, Lactococcus lactis MNC24 and Lactobacillus fermentum MNC34 and yeasts: Issatchenkia orientalis MNC20Y and Saccharomyces cerevisiae MNC21Y were used to produce Obushera, a fermented sorghum beverage. Microbial counts, pH, sugars, organic acids, and volatile compounds in starter culture and spontaneous fermentations were monitored during 48 hrs. Maximum counts of LAB (8.4–9.4 log cfu g⁻¹) and yeasts (7.5 ± 0.1 cfu g⁻¹) starter cultures were attained in 6–48 hrs. Weissella confusa, Lc. lactis, and Lb. fermentum showed possible acid sensitivity while I. orientalis produced surface films. LAB starter cultures and their combinations with S. cerevisiae lowered pH from 5.83 to <4.5 (3.50–4.13) in a shorter time (12 hrs) than spontaneous fermentations (24 hrs). Lactococcus lactis and W. confusa metabolized glucose the fastest (p < .05) during the first 6 hrs. Lactobacillus fermentum, Lb. plantarum, and S. cerevisiae utilized glucose and maltose concurrently. Lactobacillus plantarum and S. cerevisiae additionally utilized fructose. S. cerevisiae metabolized sugars the fastest (p < .05) during the first 12–24 hrs. Lactobacillus plantarum and W. confusa produced the highest (p < .05) amounts of lactate (5.43 g kg⁻¹) and diacetyl (9.5 mg kg⁻¹), respectively. LAB also produced acetate, ethanol, acetaldehyde, acetone, and acetoin. Coculturing LAB with S. cerevisiae reduced (p < .05) lactate and diacetyl yield. Yeasts produced high amounts of acetaldehyde and methyl alcohols. Issatchenkia orientalis produced higher (p < .05) amounts of 2‐methy‐1‐propanol and 3‐methyl‐1‐butanol than S. cerevisiae. Combinations of LAB with S. cerevisiae produced a profile flavor compounds close to that of spontaneously fermented Obushera. These combinations can be adopted for controlled fermentation of Obushera and related fermented cereal products.

Application of starter cultures in the production of Enturire - a traditional sorghum-based alcoholic beverage

Enturire is an alcoholic sorghum- and honey-based beverage traditionally produced by spontaneous fermentation. Its fermentation process is lengthy (5-7 days), does not guarantee product quality and safety and thus necessitates use of pure starter cultures. This study compared a modified production process of Enturire, with honey added at the start to the traditional one (honey added 3 days into the fermentation). The study also evaluated two starter culture combinations (L. plantarum MNC 21 +  S. cerevisiae MNC 21 Y) and (L. plantarum MNC 21 +  W. confusa MNC 20 +  S. cerevisiae MNC 21Y). Microbial counts, pH, alcohol content, titratable acidity, (TA) and consumer acceptability of the Enturire were determined. Lactic acid bacteria (LAB) and yeast counts increased from 4-6 log cfu/ml to 8-9 log cfu/ml and 3-4 log cfu/ml to 5-8 log cfu/ml, respectively. Acidification of Enturire to pH <4.5 was significantly (p < .05) faster (12 hr) with starter fermentations than in the modified (18 hr) and the traditional processes (31 hr). More alcohol (9.2%-9.4%) was produced by the starters than the spontaneous fermentations (3.24%-4.38%). The modified process without starters produced a more acceptable (p < .05) product than the traditional process. The starters produced acceptable Enturire within 12 hr with pH, acidity, and alcohol content of about 3.8, 0.7%, and 2.5%-3.5%. Both starter combinations can thus be used to produce safe and acceptable Enturire in a short time.

Novel Production Protocol for Small-scale Manufacture of Probiotic Fermented Foods

A novel dried bacterial consortium of Lactobacillus rhamnosus yoba 2012 and Streptococcus thermophilus C106 is cultured in 1 L of milk. This fresh starter can be used for the production of fermented milk and other fermented foods either at home or at small-scale in rural settings. For the fresh starter, 1 L of milk is pasteurized in a pan that fits into a larger pan containing water, placed on a source of heat. In this water bath, the milk is heated and incubated at 85 °C for 30 min. Thereafter, the milk is cooled down to 45 °C, transferred to a vacuum flask, inoculated with the dried bacteria and left for at least 16 hr between 30 °C and 45 °C. For the purpose of frequent home production, the fresh starter is frozen into ice cubes, which can be used for the production of small volumes of up to 2 L of fermented milk. For the purpose of small-scale production in resource-poor countries, pasteurization of up to 100 L of milk is conducted in milk cans that are placed in a large sauce pan filled with water and heated on a fire at 85 °C for 30 min, and subsequently cooled to 45 °C. Next, the 100 L batch is inoculated with the 1 L freshly prepared starter mentioned before. To assure an effective fermentation at a temperature between 30 and 45 °C, the milk can is covered with a blanket for 12 hr. For the production of non-dairy fermented foods, the fresh starter is left in a cheese cloth for 12 hr, and the drained-off whey can be subsequently used for the inoculation of a wide range of food raw materials, including vegetables and cereal-based foods.

Microbiological characterization of traditional dough fermentation starter (Jiaozi) for steamed bread making by culture-dependent and culture-independent methods

In this study, the microbial composition of two types of Jiaozi (a dough fermentation starter in making steamed bread) was investigated using both culture-dependent and culture-independent (PCR-DGGE) methods. The numbers of the cultivable bacteria on MRS at 30°C and yeast on YPD at 28°C in the maize flour Jiaozi (MFJ) were 9.21±0.16 Log CFU/g and 9.18±0.05 Log CFU/g, respectively, which were higher than that in the rice flour Jiaozi (RFJ) (P<0.05). A total of 140 bacteria and 124 yeasts were isolated and identified on the basis of the sequences of their 16S rRNA gene and ITS region. The culture-dependent method showed that Acetobacter tropicalis and Enterococcus durans were the predominant bacteria strains in MFJ, and accounted for 45.7% and 25.7% of the bacteria, and Lactobacillus plantarum and Pediococcus pentosaceus represented 12.8% and 8.6%. In the RFJ sample, the most prominent isolate was P. pentosaceus (38.6%), followed by L. plantarum (24.3%), A. tropicalis (22.8%), and E. durans (5.7%). P. pentosaceus and L. plantarum were also detected in both starters by PCR-DGGE, while some bacteria species such as A. tropicalis and E. durans, recovered as pure cultures, were not detected by direct PCR-DGGE. On the other hand, Lactobacillus brevis, Weissella sp. and Lactobacillus alimentarius detected by PCR-DGGE were not recovered in any of the media and conditions used. In the MFJ sample, the isolated main yeast species were identified as Wickerhamomyces anomalus (67.2%), Saccharomyces cerevisiae (27.9%) and Torulaspora delbrueckii (4.9%). In addition to S. cerevisiae (42.9%), W. anomalus (27.0%) and T. delbrueckii (7.9%), Saccharomycopsis fibuligera was also identified as the predominant isolate in RFJ samples and accounted for 22.2%. PCR-DGGE also indicated the presence of W. anomalus and S. cerevisiae in both MFJ and RFJ starters and S. fibuligera was also detected in RFJ, but T. delbrueckii was not detected in both samples.

A novel consortium of Lactobacillus rhamnosus and Streptococcus thermophilus for increased access to functional fermented foods

BACKGROUND

The lactic acid bacterium Lactobacillus rhamnosus GG is the most studied probiotic bacterium with proven health benefits upon oral intake, including the alleviation of diarrhea. The mission of the Yoba for Life foundation is to provide impoverished communities in Africa increased access to Lactobacillus rhamnosus GG under the name Lactobacillus rhamnosus yoba 2012, world's first generic probiotic strain. We have been able to overcome the strain's limitations to grow in food matrices like milk, by formulating a dried starter consortium with Streptococcus thermophilus that enables the propagation of both strains in milk and other food matrices. The affordable seed culture is used by people in resource-poor communities.

RESULTS

We used S. thermophilus C106 as an adjuvant culture for the propagation of L. rhamnosus yoba 2012 in a variety of fermented foods up to concentrations, because of its endogenous proteolytic activity, ability to degrade lactose and other synergistic effects. Subsequently, L. rhamnosus could reach final titers of 1E+09 CFU ml(-1), which is sufficient to comply with the recommended daily dose for probiotics. The specific metabolic interactions between the two strains were derived from the full genome sequences of L. rhamnosus GG and S. thermophilus C106. The piliation of the L. rhamnosus yoba 2012, required for epithelial adhesion and inflammatory signaling in the human host, was stable during growth in milk for two rounds of fermentation. Sachets prepared with the two strains, yoba 2012 and C106, retained viability for at least 2 years.

CONCLUSIONS

A stable dried seed culture has been developed which facilitates local and low-cost production of a wide range of fermented foods that subsequently act as delivery vehicles for beneficial bacteria to communities in east Africa.

Genomics, evolution, and molecular epidemiology of the Streptococcus bovis/Streptococcus equinus complex (SBSEC)

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a group of human and animal derived streptococci that are commensals (rumen and gastrointestinal tract), opportunistic pathogens or food fermentation associates. The classification of SBSEC has undergone massive changes and currently comprises 7 (sub)species grouped into four branches based on sequences identities: the Streptococcus gallolyticus, the Streptococcus equinus, the Streptococcus infantarius and the Streptococcus alactolyticus branch. In animals, SBSEC are causative agents for ruminal acidosis, potentially laminitis and infective endocarditis (IE). In humans, a strong association was established between bacteraemia, IE and colorectal cancer. Especially the SBSEC-species S. gallolyticus subsp. gallolyticus is an emerging pathogen for IE and prosthetic joint infections. S. gallolyticus subsp. pasteurianus and the S. infantarius branch are further associated with biliary and urinary tract infections. Knowledge on pathogenic mechanisms is so far limited to colonization factors such as pili and biofilm formation. Certain strain variants of S. gallolyticus subsp. macedonicus and S. infantarius subsp. infantarius are associated with traditional dairy and plant-based food fermentations and display traits suggesting safety. However, due to their close relationship to virulent strains, their use in food fermentation has to be critically assessed. Additionally, implementing accurate and up-to-date taxonomy is critical to enable appropriate treatment of patients and risk assessment of species and strains via recently developed multilocus sequence typing schemes to enable comparative global epidemiology. Comparative genomics revealed that SBSEC strains harbour genomics islands (GI) that seem acquired from other streptococci by horizontal gene transfer. In case of virulent strains these GI frequently encode putative virulence factors, in strains from food fermentation the GI encode functions that are pivotal for strain performance during fermentation. Comparative genomics is a powerful tool to identify acquired pathogenic functions, but there is still an urgent need for more physiological and epidemiological data to understand SBSEC-specific traits.

Genome Sequence of the Yeast Cyberlindnera fabianii (Hansenula fabianii)

The yeast Cyberlindnera fabianii is used in wastewater treatment, fermentation of alcoholic beverages, and has caused blood infections. To assist in the accurate identification of this species, and to determine the genetic basis for properties involved in fermentation and water treatment, we sequenced and annotated the genome of C. fabianii (YJS4271).

Evaluation of the microbial community, acidity and proximate composition of akamu, a fermented maize food

BACKGROUND

Akamu is a lactic acid-fermented cereal-based food that constitutes a major infant complementary food in most West African countries. The identities of LAB populations from DGGE analysis and conventionally isolated LAB and yeasts from traditionally fermented akamu were confirmed by PCR sequencing analysis. The relationships between pH, acidity and lactic acid levels and proximate composition of the akamu samples were investigated.

RESULTS

The LAB communities in the akamu samples comprised mainly Lactobacillus species, including Lb. fermentum, Lb. plantarum, Lb. delbrueckii ssp. bulgaricus and Lb. helveticus, as well as Lactococcus lactis ssp. cremoris. Identified yeasts were Candida tropicalis, Candida albicans, Clavispora lusitaniae and Saccharomyces paradoxus. Low pH (3.22-3.95) was accompanied by high lactic acid concentrations (43.10-84.29 mmol kg⁻¹). Protein (31.88-74.32 g kg⁻¹) and lipid (17.74-36.83 g kg⁻¹ contents were negatively correlated with carbohydrate content (897.48-926.20 g kg⁻¹, of which ≤1 g kg⁻¹ was sugars). Ash was either not detected or present only in trace amounts (≤4 g kg⁻¹). Energy levels ranged from 17.29 to 18.37 kJ g⁻¹.

CONCLUSION

The akamu samples were predominantly starchy foods and had pH < 4.0 owing to the activities of fermentative LAB.