African fermented dairy products - Overview of predominant technologically important microorganisms focusing on African Streptococcus infantarius variants and potential future applications for enhanced food safety and security

Probiotic Bacillus as fermentation agents: Status, potential insights, and future perspectives

Probiotic Bacillus strains can solve the problems of single flavor and long fermentation time of fermented products caused by the lack of certain functional genes and insufficient metabolism ability of fermenter strains (Lactobacillus and Bifidobacterium) at the present stage. There is a lack of systematic evaluation and review of probiotic Bacillus as food fermentation agents. In this paper, it is observed that probiotic Bacillus strains are involved to varying degrees in liquid-state, semi-solid state, and solid-state fermentation and are widely present in solid-state fermented foods. Probiotic Bacillus strains not only produce abundant proteases and lipases, but also effective antifungal lipopeptides and extracellular polymers, thus enhancing the flavor, nutritional value and safety of fermented foods. Bacillus with probiotic qualities is an underutilized group of probiotic food fermentation agents, which give a potential for the development of fermentation technology in the food business and the integration of ancient traditional fermentation techniques.

Draft genome sequence of Lactococcus lactis subsp. lactis RTIII518: a potent dairy starter isolated from traditional lait caillé in Burkina Faso

Lactococcus lactis subsp. lactis RTIII518 was isolated from lait caillé, a traditional fermented milk product from Burkina Faso. The draft genome size is 25,554,260 base pairs with 76 contigs, 34.26% average content of GC, 50 tRNAs, 4 rRNA, and 2,498 coding genes.

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.

Comparative analyses of the bacterial communities present in the spontaneously fermented milk products of Northeast India and West Africa

Introduction

Spontaneous fermentation of raw cow milk without backslopping is in practice worldwide as part of the traditional food culture, including "Doi" preparation in earthen pots in Northeast India, "Kindouri" of Niger and "Fanire" of Benin prepared in calabash vessels in West Africa. Very few reports are available about the differences in bacterial communities that evolved during the spontaneous mesophilic fermentation of cow milk in diverse geographical regions.

Methods

In this study, we used high throughput amplicon sequencing of bacterial 16S rRNA gene to investigate 44 samples of naturally fermented homemade milk products and compared the bacterial community structure of these foods, which are widely consumed in Northeast India and Western Africa.

Results and discussion

The spontaneous milk fermentation shared the lactic acid bacteria, mainly belonging to Lactobacillaceae (Lactobacillus) and Streptococcaceae (Lactococcus) in these two geographically isolated regions. Indian samples showed a high bacterial diversity with the predominance of Acetobacteraceae (Gluconobacter and Acetobacter) and Leuconostoc, whereas Staphylococcaceae (Macrococcus) was abundant in the West African samples. However, the Wagashi cheese of Benin, prepared by curdling the milk with proteolytic leaf extract of Calotrophis procera followed by natural fermentation, contained Streptococcaceae (Streptococcus spp.) as the dominant bacteria. Our analysis also detected several potential pathogens, like Streptococcus infantarius an emerging infectious foodborne pathogen in Wagashi samples, an uncultured bacterium of Enterobacteriaceae in Kindouri and Fanire samples, and Clostridium spp. in the Doi samples of Northeast India. These findings will allow us to develop strategies to address the safety issues related to spontaneous milk fermentation and implement technological interventions for controlled milk fermentation by designing starter culture consortiums for the sustainable production of uniform quality products with desirable functional and organoleptic properties.

Antimicrobial Resistance of Lactic Acid Bacteria from Nono, a Naturally Fermented Milk Product

BACKGROUND

Antimicrobial resistance (AMR) is one of the biggest threats to public health. The food chain has been recognised as a vehicle for transmitting AMR bacteria. However, information about resistant strains isolated from African traditional fermented foods remains limited. Nono is a traditional, naturally fermented milk product consumed by many pastoral communities across West Africa. The main aim of this study was to investigate and determine the AMR patterns of lactic acid bacteria (LAB) involved in the traditional fermentation of milk for Nono production, and the presence of transferable AMR determinants.

METHODS

One hundred (100) LAB isolates from Nono identified in a previous study as Limosilactobacillus fermentum, Lactobacillus delbrueckii, Streptococcus thermophilus, Streptococcus infantarius, Lentilactobacillus senioris, Leuconostoc pseudomesenteriodes, and Enterococcus thailandicus were investigated. The minimum inhibitory concentration (MIC) was determined for 18 antimicrobials using the micro-broth dilution method. In addition, LAB isolates were screened for 28 antimicrobial resistance genes using PCR. The ability of LAB isolates to transfer tetracycline and streptomycin resistance genes to Enterococcus faecalis was also investigated.

RESULTS

The experiments revealed variable antimicrobial susceptibility according to the LAB isolate and the antimicrobial tested. The tetracycline resistance genes tet(S) and tet(M) were detected in isolates Ent. thailandicus 52 and S. infantarius 10. Additionally, aad(E) encoding resistance to streptomycin was detected in Ent. thailandicus 52. The conjugation experiments suggested that the tet(S) and aad(E) genes were transferable in vitro from isolate Ent. thailandicus 52 to Ent. faecalis JH2-2.

SIGNIFICANCE AND IMPACT

Traditional fermented foods play a significant role in the diet of millions of people in Africa, yet their contribution to the burden of AMR is largely unknown. This study highlights that LAB involved in traditionally fermented foods could be potential reservoirs of AMR. It also underscores the relevant safety issues of Ent. thailandicus 52 and S. infantarius 10 for use as starter cultures as they carry transferable AMR genes. Starter cultures are an essential aspect of improving the safety and quality attributes of African fermented foods. However, AMR monitoring is an important safety aspect in the selection of starter cultures for improving traditional fermentation technologies.

Probiotic therapy, African fermented foods and food-derived bioactive peptides in the management of SARS-CoV-2 cases and other viral infections

The current paper focuses on the impact of probiotics, African fermented foods and bioactive peptides on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection severity and related viral infections. Using probiotics or bioactive peptides as therapeutic adjuncts appears superior to standard care alone. Probiotics play critical roles in innate and adaptive immune modulation by balancing the gut microbiota to combat viral infections, secondary bacterial infections and microbial dysbiosis. African fermented foods contain abundant potential probiotic microorganisms such as the lactic acid bacteria (LAB), Saccharomyces, and Bacillus. More so, fermented food-derived bioactive peptides play vital roles in preventing cardiovascular diseases, hypertension, lung injury, diabetes, and other COVID-19 comorbidities. Regularly incorporating potential probiotics and bioactive peptides into diets should enable a build-up of the benefits in the body system that may result in a better prognosis, especially in COVID-19 patients with underlying complexities. Despite the reported therapeutic potentials of probiotics and fermented foods, numerous setbacks exist regarding their application in disease management. These shortfalls underscore an evident need for more studies to evaluate the specific potentials of probiotics and traditional fermented foods in ameliorating SARS-CoV-2 and other viral infections.

Immune System and Epidemics: The Role of African Indigenous Bioactive Substances

With over 6 million coronavirus pandemic deaths, the African continent reported the lowest death rate despite having a high disease burden. The African community's resilience to the pandemic has been attributed to climate and weather conditions, herd immunity, repeated exposure to infectious organisms that help stimulate the immune system, and a disproportionately large youth population. In addition, functional foods, herbal remedies, and dietary supplements contain micronutrients and bioactive compounds that can help boost the immune system. This review identified significant traditional fermented foods and herbal remedies available within the African continent with the potential to boost the immune system in epidemics and pandemics. Methodology: Databases, such as PubMed, the Web of Science, and Scopus, were searched using relevant search terms to identify traditional African fermented foods and medicinal plants with immune-boosting or antiviral capabilities. Cereal-based fermented foods, meat-, and fish-based fermented foods, and dairy-based fermented foods containing antioxidants, immunomodulatory effects, probiotics, vitamins, and peptides were identified and discussed. In addition, nine herbal remedies and spices belonging to eight plant families have antioxidant, immunomodulatory, anti-inflammatory, neuroprotective, hepatoprotective, cardioprotective, and antiviral properties. Peptides, flavonoids, alkaloids, sterols, ascorbic acid, minerals, vitamins, and saponins are some of the bioactive compounds in the remedies. Bioactive compounds in food and plants significantly support the immune system and help increase resistance against infectious diseases. The variety of food and medicinal plants found on the African continent could play an essential role in providing community resilience against infectious diseases during epidemics and pandemics. The African continent should investigate nutritional, herbal, and environmental factors that support healthy living and longevity.

Safety and Quality of Milk and Milk Products in Senegal—A Review

Historically, local milk production in Senegal has struggled to keep up with the demands of consumers, so there has been a heavy reliance on imported milk and milk products. More recently, efforts have been made to improve local dairy production by establishing large, organized dairies that collect milk from rural production areas and developing small-scale processing units, such as mini dairies. The local dairy value chain in Senegal consists of (1) informal collection systems where farmers commonly deliver milk directly to dairies; (2) traditional and artisanal processing using simple equipment and techniques; and (3) short local marketing and sale circuits. Most West African dairy sectors are dominated by raw, unpasteurized milk or traditional, spontaneously fermented milk products, such as lait caillé in Senegal, sold through small-scale channels without a cold chain, so the risk of food safety hazards may be increased. Microbiological, chemical, and physical hazards have been found in milk and milk products across West Africa. There is a need to educate milk producers, small-scale processors, and vendors on the importance of refrigerating milk immediately after milking as well as maintaining the cold chain until the milk is heat treated and, subsequently, until the milk is marketed to the consumer. However, without assistance, obtaining the equipment necessary for cold storage and processing of milk can be challenging.

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.

Bacterial diversity of Gambian traditional fermented milk, "Kosam"

We have clarified the microbiological characterization of Gambian traditional fermented milk (FM), "Kosam." Two samples of FM were collected at two regions in The Gambia in 2019. The microbiota of these samples was analyzed by culture-dependent methods and Illumina sequencing. The number of lactic acid bacteria (LAB) in FM from Central River Region (CRR) and Lower River Region (LRR) was 8.27 ± 0.08 log CFU/ml and 7.21 ± 0.09 log CFU/ml, respectively. While no coliforms and Escherichia coli were detected in CRR-FM, LRR-FM contained 5.73 ± 0.17 log CFU/ml of coliforms and 4.82 ± 0.13 log CFU/ml of E. coli. The dominant viable LAB in FM from CRR was Lactobacillus delbrueckii, followed by Streptococcus lutetiensis, while that from LRR was Lactococcus lactis. The metagenomic analysis also revealed that these species were dominant in these Gambian traditional FM. Furthermore, it also revealed the possibility of the presence of pathogens such as Klebsiella spp. This study enhanced the knowledge of Gambian FM and contributed to the elucidation of microbial communities.

African fermented foods: overview, emerging benefits, and novel approaches to microbiome profiling

Traditional fermented foods are of major importance with respect to the socio-economic growth, food security, nutrition, and health of African consumers. In several African countries, traditional fermentation processes provide a means of food preservation, improving the shelf life and adding to the nutrients in the food products. As with any fermented foods, the associated food microbiota is of great importance and interest. Recent studies on the microbiome of African fermented foods using high-throughput DNA sequencing techniques have revealed the presence of diverse microbial populations of fundamental, technological, and commercial interest that could be harnessed to further improve health, food safety, and quality. This review provides an overview of African fermented foods, their microbiota, and the health-promoting potential of these foods and microbes.

Bovine Colostrum for Human Consumption—Improving Microbial Quality and Maintaining Bioactive Characteristics through Processing

The main purpose of bovine colostrum, being the milk secreted by a cow after giving birth, is to transfer passive immunity to the calf. The calves have an immature immune system as they lack immunoglobulins (Igs). Subsequently, the supply of good quality bovine colostrum is required. The quality of colostrum is classified by low bacterial counts and adequate Ig concentrations. Bacterial contamination can contain a variety of human pathogens or high counts of spoilage bacteria, which has become more challenging with the emerging use of bovine colostrum as food and food supplements. There is also a growing risk for the spread of zoonotic diseases originating from bovines. For this reason, processing based on heat treatment or other feasible techniques is required. This review provides an overview of literature on the microbial quality of bovine colostrum and processing methods to improve its microbial quality and keep its nutritional values as food. The highlights of this review are as follows: high quality colostrum is a valuable raw material in food products and supplements; the microbial safety of bovine colostrum is increased using an appropriate processing-suitable effective heat treatment which does not destroy the high nutrition value of colostrum; the heat treatment processes are cost-effective compared to other methods; and heat treatment can be performed in both small- and large-scale production.

Identification and characterisation of the lactic acid bacteria associated with the traditional fermentation of dairy fermented product

The aim of this research was to identify the key lactic acid bacteria associated with the fermentation of dairy traditional fermented products for developing starter cultures for controlled fermentation. A total of 100 lactic acid bacteria (LAB) were isolated from dairy traditional fermented products. Samples were obtained from eight producers in the South East of Nigeria. Isolates were identified by phenotypic and genotypic techniques including rep-PCR genotyping and sequencing of the 16S rRNA, pheS and rpoA genes. Isolates were characterised for antimicrobial activity against foodborne pathogens, exopolysaccharide (EPS) production and survival at low pH and in the presence of bile salts. All isolates clustered into 11 distinct rep-PCR groups and were identified as Lactobacillus fermentum (40%), Lactobacillus delbrueckii (23%), Streptococcus thermophilus (22%), Streptococcus infantarius (10%), Lactobacillus senioris (2%), Leuconostoc pseudomesenteriodes (2%) and Enterococcus thailandicus (1%). Lactobacillus fermentum showed a broad spectrum antimicrobial activity and survival at low pH, while Lactobacillus delbrueckii was able to tolerate low pH and produce EPS. All isolates survived in vitro exposure to 1% (w/v) bile salts over a 3-h period. L. fermentum, L. delbrueckii and S. thermophilus could be used to simulate the fermentation of dairy traditional fermented products.

Recent Advances in Camel Milk Processing

Simple Summary

The camel milk market was limited for a long time by its almost exclusive self-consumption use in nomadic camps. Significant development has been observed for the past two or three decades, including internationally, boosted by its reputation regarding its health effects for regular consumers. Such emergence has led the stakeholders in the sector to offer diversified products corresponding to the tastes of increasingly urbanized consumers, more sensitive to “modern” products. Thus, traditionally drunk in raw or naturally fermented form, camel milk has undergone unprecedented transformations such as pasteurization, directed fermentation, cheese or yoghurt processing, and manufacture of milk powder for the export market. However, the specific characteristics of this milk (composition, physical properties) mean that the technologies applied (copied from technologies used for cow milk) must be adapted. In this review, some technological innovations are presented, enabling stakeholders of the camel milk sector to satisfy the demand of manufacturers and consumers.

Abstract

Camel milk is a newcomer to domestic markets and especially to the international milk market. This recent emergence has been accompanied by a diversification of processed products, based on the technologies developed for milk from other dairy species. However, technical innovations had to be adapted to a product with specific behavior and composition. The transformation of camel milk into pasteurized milk, fermented milk, cheese, powder, or other products was supported, under the pressure of commercial development, by technological innovations made possible by a basic and applied research set. Some of these innovations regarding one of the less studied milk sources are presented here, as well as their limitations. Technical investigations for an optimal pasteurization, development of controlled fermentation at industrial scale, control of cheese technology suitable for standardized production, and improvements in processes for the supply of a high-quality milk powder are among the challenges of research regarding camel milk.

A review of microbes and chemical contaminants in dairy products in sub-Saharan Africa

Animal milk types in sub-Saharan Africa (SSA) are processed into varieties of products using different traditional methods and are widely consumed by households to support nutritional intake and diet. Dairy products contain several microorganisms, their metabolites, and other chemical compounds, some with health benefits and many others considered as potential health hazards. Consumption of contaminated milk products could have serious health implications for consumers. To access the safety of milk products across SSA, studies in the region investigating the occurrences of pathogens as well as chemical compounds such as heat stable toxins and veterinary drug residues in animal milk and its products were reviewed. This is done with a holistic view in light of the emerging exposome paradigm for improving food safety and consumer health in the region. Herein, we showed that several published studies in SSA applied conventional and/or less sensitive methods in detecting microbial species and chemical contaminants. This has serious implications in food safety because the correct identity of a microbial species and accurate screening for chemical contaminants is crucial for predicting the potential human health effects that undermine the benefits from consumption of these foods. Furthermore, we highlighted gaps in determining the extent of viral and parasitic contamination of milk products across SSA as well as investigating multiple classes of chemical contaminants. Consequently, robust studies should be conducted in this regard. Also, efforts such as development cooperation projects should be initiated by all stakeholders including scientists, regulatory agencies, and policy makers to improve the dairy product chain in SSA in view of safeguarding consumer health.

Diversity and Antimicrobial Resistance in the Streptococcus bovis/Streptococcus equinus Complex (SBSEC) Isolated from Korean Domestic Ruminants

S. bovis/S. equinus complex (SBSEC) includes lactic acid-producing bacteria considered as the causative agent associated with acute rumen lactic acidosis in intensive ruminants. Considering the limited information on the detailed characteristics and diversity of SBSEC in Korea and the emergence of antimicrobial resistance (AMR), we investigated the diversity of SBSEC from domestic ruminants and verified the presence of antimicrobial resistance genes (ARGs) against several antimicrobials with their phenotypic resistance. Among 51 SBSEC isolates collected, two SBSEC members (S. equinus and S. lutetiensis) were identified; sodA-based phylogenetic analyses and comparisons of overall genome relatedness revealed potential plasticity and diversity. The AMR rates of these SBSEC against erythromycin, clindamycin, and tetracycline were relatively lower than those of other SBSEC isolates of a clinical origin. An investigation of the ARGs against those antimicrobials indicated that tetracycline resistance of SBSECs generally correlated with the presence of tet(M)-possessing Tn916-like transposon. However, no correlation between the presence of ARGs and phenotypic resistance to erythromycin and clindamycin was observed. Although a limited number of animals and their SBSEC isolates were examined, this study provides insights into the potential intraspecies biodiversity of ruminant-origin SBSEC and the current status on antimicrobial resistance of the bacteria in the Korean livestock industry.

Diversity and Antimicrobial Resistance in the Streptococcus bovis/Streptococcus equinus Complex (SBSEC) Isolated from Korean Domestic Ruminants

S. bovis/S. equinus complex (SBSEC) includes lactic acid-producing bacteria considered as the causative agent associated with acute rumen lactic acidosis in intensive ruminants. Considering the limited information on the detailed characteristics and diversity of SBSEC in Korea and the emergence of antimicrobial resistance (AMR), we investigated the diversity of SBSEC from domestic ruminants and verified the presence of antimicrobial resistance genes (ARGs) against several antimicrobials with their phenotypic resistance. Among 51 SBSEC isolates collected, two SBSEC members (S. equinus and S. lutetiensis) were identified; sodA-based phylogenetic analyses and comparisons of overall genome relatedness revealed potential plasticity and diversity. The AMR rates of these SBSEC against erythromycin, clindamycin, and tetracycline were relatively lower than those of other SBSEC isolates of a clinical origin. An investigation of the ARGs against those antimicrobials indicated that tetracycline resistance of SBSECs generally correlated with the presence of tet(M)-possessing Tn916-like transposon. However, no correlation between the presence of ARGs and phenotypic resistance to erythromycin and clindamycin was observed. Although a limited number of animals and their SBSEC isolates were examined, this study provides insights into the potential intraspecies biodiversity of ruminant-origin SBSEC and the current status on antimicrobial resistance of the bacteria in the Korean livestock industry.

Diversity and Antimicrobial Resistance in the Streptococcus bovis/Streptococcus equinus Complex (SBSEC) Isolated from Korean Domestic Ruminants

S. bovis/S. equinus complex (SBSEC) includes lactic acid-producing bacteria considered as the causative agent associated with acute rumen lactic acidosis in intensive ruminants. Considering the limited information on the detailed characteristics and diversity of SBSEC in Korea and the emergence of antimicrobial resistance (AMR), we investigated the diversity of SBSEC from domestic ruminants and verified the presence of antimicrobial resistance genes (ARGs) against several antimicrobials with their phenotypic resistance. Among 51 SBSEC isolates collected, two SBSEC members (S. equinus and S. lutetiensis) were identified; sodA-based phylogenetic analyses and comparisons of overall genome relatedness revealed potential plasticity and diversity. The AMR rates of these SBSEC against erythromycin, clindamycin, and tetracycline were relatively lower than those of other SBSEC isolates of a clinical origin. An investigation of the ARGs against those antimicrobials indicated that tetracycline resistance of SBSECs generally correlated with the presence of tet(M)-possessing Tn916-like transposon. However, no correlation between the presence of ARGs and phenotypic resistance to erythromycin and clindamycin was observed. Although a limited number of animals and their SBSEC isolates were examined, this study provides insights into the potential intraspecies biodiversity of ruminant-origin SBSEC and the current status on antimicrobial resistance of the bacteria in the Korean livestock industry.

Zoonotic Tuberculosis in Humans: Control, Surveillance, and the One Health Approach

Zoonotic tuberculosis is a reemerging infectious disease in high-income countries and a neglected one in low- and middle-income countries. Despite major advances in its control as a result of milk pasteurization, its global burden is unknown, especially due the lack of surveillance data. Additionally, very little is known about control strategies. The purpose of this review was to contextualize the current knowledge about the epidemiology of zoonotic tuberculosis and to describe the available evidence regarding surveillance and control strategies in high-, middle-, and low-income countries. We conducted this review enriched by a One Health perspective, encompassing its inherent multifaceted characteristics. We found that the burden of zoonotic tuberculosis is likely to be underreported worldwide, with higher incidence in low-income countries, where the surveillance systems are even more fragile. Together with the lack of specific political commitment, surveillance data is affected by lack of a case definition and limitations of diagnostic methods. Control measures were dependent on risk factors and varied greatly between countries. This review supports the claim that a One Health approach is the most valuable concept to build capable surveillance systems, resulting in effective control measures. The disease characteristics and suggestions to implement surveillance and control programs are discussed.

Microbial Safety of Milk Production and Fermented Dairy Products in Africa

In Africa, milk production, processing and consumption are integral part of traditional food supply, with dairy products being a staple component of recommended healthy diets. This review provides an overview of the microbial safety characteristics of milk production and fermented dairy products in Africa. The object is to highlight the main microbial food safety hazards in the dairy chain and to propose appropriate preventive and control measures. Pathogens of public health concern including Mycobacterium bovis, Brucella abortus and Coxiella burnettii, which have largely been eradicated in many developed nations, still persist in the dairy chain in Africa. Factors such as the natural antimicrobial systems in milk and traditional processing technologies, including fermentation, heating and use of antimicrobial additives, that can potentially contribute to microbial safety of milk and dairy products in Africa will be discussed. Practical approaches to controlling safety hazards in the dairy chain in Africa have been proposed. Governmental regulatory bodies need to set the necessary national and regional safety standards, perform inspections and put measures in place to ensure that the standards are met, including strong enforcement programs within smallholder dairy chains. Dairy chain actors would require upgraded knowledge and training in preventive approaches such as good agricultural practices (GAP), hazard analysis and critical control points (HACCP) design and implementation and good hygienic practices (GHPs). Food safety education programs should be incorporated into school curricula, beginning at the basic school levels, to improve food safety cognition among students and promote life-long safe food handling behaviour.

Traditional milk transformation schemes in Côte d'Ivoire and their impact on the prevalence of Streptococcus bovis complex bacteria in dairy products

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) and possibly Streptococcus infantarius subsp. infantarius (Sii) are associated with human and animal diseases. Sii predominate in spontaneously fermented milk products with unknown public health effects. Sii/SBSEC prevalence data from West Africa in correlation with milk transformation practices are limited. Northern Côte d'Ivoire served as study area due to its importance in milk production and consumption and to link a wider Sudano-Sahelian pastoral zone of cross-border trade. We aimed to describe the cow milk value chain and determine Sii/SBSEC prevalence with a cross-sectional study. Dairy production practices were described as non-compliant with basic hygiene standards. The system is influenced by secular sociocultural practices and environmental conditions affecting product properties. Phenotypic and molecular analyses identified SBSEC in 27/43 (62.8%) fermented and 26/67 (38.8%) unfermented milk samples. Stratified by collection stage, fermented milk at producer and vendor levels featured highest SBSEC prevalence of 71.4% and 63.6%, respectively. Sii with 62.8% and 38.8% as well as Streptococcus gallolyticus subsp. macedonicus with 7.0% and 7.5% were the predominant SBSEC species identified among fermented and unfermented milk samples, respectively. The population structure of Sii/SBSEC isolates seems to reflect evolving novel dairy-adapted, non-adapted and potentially pathogenic lineages. Northern Côte d'Ivoire was confirmed as area with high Sii presence in dairy products. The observed production practices and the high diversity of Sii/SBSEC supports in-depth investigations on Sii ecology niche, product safety and related technology in the dairy value chain potentially affecting large population groups across sub-Saharan Africa.

Microbiology of Ethiopian Traditionally Fermented Beverages and Condiments

Globally, fermented beverage and condiments are made by using different conventional practices, raw materials, and microorganisms. This paper presents the available literature review on the technology and microbiology of traditional Ethiopian beverages and condiment products. Traditional fermented beverage and condiment products have essential vitamins, minerals, enzymes, and antioxidants that are all enhanced through the process of traditional fermentation practices. In Ethiopia, fermented beverage and condiment products have practiced in a long history. During the production of traditional fermented beverage and condiment products, controlled natural fermentation process with the absence of starter cultures are used to initiate it. Moreover, the preparation of many traditionally fermented beverage and condiment products is still practiced in a household art, thereby a wide variety of fermented beverages and condiments are consumed in Ethiopia. In conclusion, the review discusses the nature of the beverage and condiment preparation, poor traditional household processing, and the extent and limitation of scientific work done so far and suggests some recommendations to limit the problem in Ethiopia.

Technological properties of indigenous Lactococcus lactis strains isolated from Lait caillé, a spontaneous fermented milk from Burkina Faso

The experiments reported in this research paper aimed to determine the technological properties of indigenous Lactococcus lactis strains isolated from Lait caillé, a spontaneous fermented milk, from the perspective of starter culture development. Fermentations were conducted to determine the acidification patterns. The ropy character, growth in 0.04 g/ml NaCl and citrate metabolism were additionally tested. Furthermore, the rheological properties of samples from selected strains and the impact of cold storage were evaluated. Based on the rate of acidification, the indigenous strains were divided into 2 groups depending on their fermentation time, i.e. 10-13 h (fast acidifier), and up to 72 h (slow acidifier), respectively. The physiological tests suggested that most of these strains produced exopolysaccharides but none could ferment citrate. The flow properties of the samples inoculated by the fast acidifier strains showed a time-dependent shear thinning behaviour, while their viscoelastic properties corresponded structurally to those of weak gels. Cold storage decreased the viscosity and CFU counts for most of the indigenous strains tested. This study is a step towards the definition of starter cultures for African spontaneous fermented milks such as Lait caillé.

Risk factors for the carriage of Streptococcus infantarius subspecies infantarius isolated from African fermented dairy products

Streptococcus infantarius subsp. infantarius (Sii) has been identified as predominant lactic acid bacteria in spontaneously fermented dairy products (FDPs) in sub-Saharan Africa including Côte d'Ivoire. However, Sii belongs to the Streptococcus bovis/Streptococcus equinus complex (SBSEC). Most SBSEC members are assumed to be involved as opportunistic pathogens in serious diseases in both humans and animals. A population-based cross-sectional survey, including 385 participants was conducted in Korhogo, northern Côte d'Ivoire, to identify risk factors for Sii fecal carriage, including consumption of local FDPs. A structured questionnaire was used to gather participant's socio-demographic and economic characteristics, their relation to livestock and dietary habits. In addition, fresh stool and milk samples were collected. The identification of Sii was done using a SBSEC-specific PCR assay targeting 16S rRNA and groEL genes. The overall prevalence of SBSEC and Sii carriage was 23.2% (confidence interval CI 95% = 18.9-27.5) and 12.0% (CI 95% = 8.4-15.5) for stool, respectively. Prevalence of Sii was significantly higher in consumers of artisanal butter compared with non-consumers (57.1% vs 10.1%, odds ratio OR: 11.9, 95% CI: 3.9-36.6), as well as in persons handling livestock (OR = 3.9; 95% CI = 1.6-9.3) and livestock primary products (OR = 5.7; 95% CI = 2.3-14.3). The closer contact with livestock was a risk factor for Sii fecal carriage. Sii strains were isolated from fresh and fermented milk products with a prevalence of 30.4% and 45.4%, respectively. Analysis of Sii population structure through the SBSEC multi locus sequence typing assay revealed a close relationship across human and dairy isolates, possibly linked to a Kenyan human isolate. All these outcomes underline the interest of in-depth investigations on the ecology, potential reservoirs and pathways of contamination by Sii at the human-animal-environment interface in comparison to yet to be collected data from Europe, Asia and the Americas to further elucidate the various roles of Sii.

Meta-Analysis and Meta-Regression Indicate Dynamic Prevalence and Moderators of Foodborne Pathogens in African Indigenous Fermented Milk

As more microbiological data for indigenous fermented milk (IFM) becomes available, concern about their microbial safety becomes eminent. Nonetheless, these data are highly fragmented, and a tool is required to integrate existing data and to provide a basis for data-driven decision making for IFM’s safety. Therefore, meta-analysis and meta-regression were conducted to estimate the prevalence of foodborne pathogens in IFM and to determine factors influencing the estimated values. Using Africa as a case, searches were systematically made for published data and relevant grey literature. Data from 18 studies in 15 countries were analyzed. Staphylococcus aureus (37%), pathogenic Escherichia coli (16%), Listeria monocytogenes (6%), and Salmonella spp. (3%) were the most prevalent pathogens with a pooled prevalence estimate of 12%. Heterogeneity among prevalence estimates was attributed to sampling point and microbial group but could be moderated by publication year, country cluster, and methods for microbial confirmation. The pooled prevalence estimates increased over time as more studies became available, whereby the odds were higher in studies from 2010 onwards than studies before 2010. From the analyses, S. aureus presented the greatest safety concern in African IFM. Future microbiological studies should take into consideration different IFM sampling points and advanced analytical methods to identify pathogens.

The impact of raw fermented milk products on perceived health and mood among Dutch adults

Purpose

The purpose of this paper was to evaluate health conditions prior to and at least two months after the start of consuming raw fermented milk (RFM) products.

Design/methodology/approach

One-Item health score, 1-item immunity score, immune status (ISQ), mood, bowel and skin conditions were rated for the period prior and post switching to RFM products. A linear mixed model was used to evaluate the post to prior RFM health and mood scores, taking into account gender, location of living and health group. Data from 390 participants (mean age of 54 years old) were included for the analysis, of which 277 (45 per cent) were allocated to the poor health group. Participants were allocated to the poor health group if they reported being immune depressed or suffering from a chronic disease prior to RFM; otherwise, they were allocated to the normal health group.

Findings

The highest intake of RFM was from RF kefir. Post RFM, people consumed around 1 glass (200 ml) of RF kefir per day. After switching to RFM, significant improvements on health and mood scores were reported. The strongest improvements after switching to RFM consumption were seen in subjects from the poor health group. With the exception of skin score, all measured health items significantly improved (p < 0.001). Health, immunity, bowel and mood scores increased with around 20 per cent in the poor health group and around 8 per cent in the normal health group. Women had more health complaints prior to RFM and had stronger health improvement post RFM compared to men. Bowel and mood scores were overall lower in women than in men. Living location had no significant impact on RFM-related health changes. This consumer survey suggests that positive health and mood changes are associated with the consumption of RFM products.

Originality/value

The consumption of RFM products improved the self-reported health status of adults. Immune-depressed people or people suffering from a chronic disease prior to RFM reported the strongest impact on their health, immunity, bowel and mood scores post switching RFM consumption compared to people with a normal health.

Identification of the predominant microbiota during production of lait caillé, a spontaneously fermented milk product made in Burkina Faso

The spontaneously fermented curdled milk product from Burkina Faso, lait caillé is prepared by traditional processing from raw unpasteurised milk. The fermentation lasts 1-3 days. This study aims to identify the predominant microbiota involved in lait caillé fermentation from cow milk. A survey on lait caillé end-products from local markets showed pH ranges of 3.5 to 4.2. Counts of total lactic acid bacteria (LAB) were 7.8 ± 0.06 to 10.0 ± 0.03 log CFU/g and yeast counts were 5.3 ± 0.06 to 8.7 ± 0.01 log CFU/g, together with considerate amounts of Enterobacteriaceae < 3.00 to 8.4 ± 0.14 log CFU/g. Sampling throughout the entire fermentation of lait caillé was performed at a traditional house-hold production site. A drop in pH from 6.7 ± 0.01 at 0 h to 4.3 ± 0.08 in the end-product (59 h) was found. Total LAB counts increased to 8.6 ± 0.02 log CFU/g in the end-product, while yeast and Enterobacteriaceae counts reached 6.4 ± 0.11 and 6.7 ± 0.00 log CFU/g, respectively. LAB and yeasts isolated during the fermentation were clustered by (GTG)₅ repetitive-PCR fingerprinting followed by 16S and 26S rRNA gene sequencing, respectively. Microbial successions were observed with Leuconostoc mesenteroides being the predominant LAB followed by Pediococcus pentosaceus and Weissella paramesenteroides at the onset, while Lactococcus lactis and Enterococcus spp. where the predominant LAB after 7 h of fermentation. During the first 18 h Candida parapsilosis was the dominant yeast species, while from 35 h to the end-product, Saccharomyces cerevisiae predominated. The microbial safety risk pointed out in this study, showed the need for implementation of good manufacturing practices including pasteurisation and use of well-defined starter cultures.

Lactic Acid Fermentation of Arabinoxylan From Nejayote by Streptococcus infantarius ssp. infantarius 25124 Isolated From Pozol

Streptococcus infantarius ssp. infantarius 25124 (Sii-25124) is a lactic acid bacterium (LAB) isolated from pozol, a refreshing beverage prepared by suspending fermented nixtamal (a thermal and alkali-treated maize dough) in water. Although Lactobacillus are the predominant strains in fermented doughs, such as sourdoughs, and non-nixtamalized fermented maize foods, the pozol microbiota is markedly different. This may be the result of the nixtamalization process, which could act as a selective force of some strains. Sii-25124 has been reported as the main amylolytic LAB in pozol; starch is the primary carbon source on nixtamal since monosaccharides and disaccharides are lost during nixtamalization; however, non-amylolytic LAB counts are higher than amylolytic LAB in pozol after 24-h fermentation suggesting that another carbon source is being used by the former bacteria. Hemicellulose (arabinoxylan in maize) becomes available via nixtamalization and is subsequently metabolized by LAB. The aim of this work was to determine whether this bacterium is able to use arabinoxylan as the only carbon source in a defined medium containing arabinoxylan extracted from either nejayote (wash water produced during nixtamal preparation), or beechwood xylan. Xylanase activity in the presence of nejayote arabinoxylan (135.8 ± 48.7 IU/mg protein) was higher than that of beechwood (62.5 ± 19.8 IU/mg protein). Other enzymatic activities, such as arabinofuranosidase and acetyl esterase, were also detected, suggesting the adaptation of the bacterium studied to nixtamal dough. It was concluded that Streptococcus infantarius 25124 isolated from pozol was able to use arabinoxylans, which are present in nixtamal dough, so fermentation does not depend exclusively on free sugars and starch.

Naturally Fermented Milk From Northern Senegal: Bacterial Community Composition and Probiotic Enrichment With Lactobacillus rhamnosus

A variety of foods fermented with lactic acid bacteria serve as dietary staples in many African communities; yet, their bacterial profiles are poorly characterized. The integration of health-promoting probiotics into naturally fermented milk products could make a profound impact on human health. Here, we characterize the bacterial community composition of a naturally fermented milk product (lait caillé) from northern Senegal, prepared in wooden bowls (lahals) with a bacterial biofilm to steer the fermentation process. We incorporated a probiotic starter culture containing the most documented probiotic strain Lactobacillus rhamnosus GG (generic strain name yoba 2012) into the local fermentation process. Bar-coded 16S rRNA amplicon sequencing of lait caillé samples indicated that the bacterial community of lait caillé has high species richness with over 100 bacterial genera; however, few have high abundance. In contrast to the diverse bacterial compositions of other characterized naturally fermented milk products, the composition of lait caillé predominantly consists of the lactic acid bacteria Streptococcus and Lactobacillus, resembling the bacterial composition in regular yogurt. The bacterial community composition of lait caillé varies geographically based on the presence of some genera, including Lactoccoccus, Enterococcus, Bifidobacterium, and Bacillus, but this trend is not consistent within production communities. The diversity of bacterial communities is much higher in the lahal biofilm than in the naturally fermented milk products, which is in turn greater than in commercial yogurts. Addition of a starter culture with L. rhamnosus yoba 2012 to milk in lahals led to substantial growth of this probiotic bacterium during the fermentation process. Two independent quantitative PCR-analyses specific for L. rhamnosus yoba 2012 indicated a 20- to 60-fold increase in the total number of probiotic bacteria in the first batch after inoculation. A similar increase of the probiotic was observed in a variation of lait caillé prepared with carbohydrate-rich millet granules (thiakry) added prior to fermentation. This study shows the feasibility of integrating health-promoting probiotic strains into naturally fermented foods produced in regions with a high prevalence of malnutrition.

Colorectal cancer-associated Streptococcus infantarius subsp. infantarius differ from a major dairy lineage providing evidence for pathogenic, pathobiont and food-grade lineages

Streptococcus infantarius subsp. infantarius (Sii), a member of the Streptococcus bovis/Streptococcus equinus complex (SBSEC), predominates as dairy-adapted and non-adapted variants in fermented dairy products (FDP) in East and West Africa. Epidemiologic data suggest an association with colorectal cancer for most SBSEC members, including Sii from Kenyan patients. Phylogenetic relationships of East African human (EAH) isolates to those of dairy and pathogenic origin were analysed to better estimate potential health implications via FDP consumption. The MLST-derived population structure was also evaluated to provide host, disease, geography and dairy adaptation associations for 157 SBSEC isolates, including 83 novel Sii/SBSEC isolates of which 40 originated from Kenyan colonoscopy patients. Clonal complex (CC) 90 was delineated as potential pathogenic CC for Sii. Single EAH, West African dairy (WAD), food and animal Sii isolates clustered within CC-90, suggesting a potential link to pathogenic traits for CC-90. The majority of EAH and WAD Sii were clustered in a shared clade distinct from CC-90 and East African dairy (EAD) isolates. This indicates shared ancestry for the EAH and WAD clade and limitations to translate disease associations of EAH and CC-90 to EAD Sii, which could support the separation of pathogenic, pathobiont/commensal and food lineages.

The Road to Infection: Host-Microbe Interactions Defining the Pathogenicity of Streptococcus bovis/Streptococcus equinus Complex Members

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises several species inhabiting the animal and human gastrointestinal tract (GIT). They match the pathobiont description, are potential zoonotic agents and technological organisms in fermented foods. SBSEC members are associated with multiple diseases in humans and animals including ruminal acidosis, infective endocarditis (IE) and colorectal cancer (CRC). Therefore, this review aims to re-evaluate adhesion and colonization abilities of SBSEC members of animal, human and food origin paired with genomic and functional host-microbe interaction data on their road from colonization to infection. SBSEC seem to be a marginal population during GIT symbiosis that can proliferate as opportunistic pathogens. Risk factors for human colonization are considered living in rural areas and animal-feces contact. Niche adaptation plays a pivotal role where Streptococcus gallolyticus subsp. gallolyticus (SGG) retained the ability to proliferate in various environments. Other SBSEC members have undergone genome reduction and niche-specific gene gain to yield important commensal, pathobiont and technological species. Selective colonization of CRC tissue is suggested for SGG, possibly related to increased adhesion to cancerous cell types featuring enhanced collagen IV accessibility. SGG can colonize, proliferate and may shape the tumor microenvironment to their benefit by tumor promotion upon initial neoplasia development. Bacteria cell surface structures including lipotheichoic acids, capsular polysaccharides and pilus loci (pil1, pil2, and pil3) govern adhesion. Only human blood-derived SGG contain complete pilus loci and other disease-associated surface proteins. Rumen or feces-derived SGG and other SBSEC members lack or harbor mutated pili. Pili also contribute to binding to fibrinogen upon invasion and translocation of cells from the GIT into the blood system, subsequent immune evasion, human contact system activation and collagen-I-binding on damaged heart valves. Only SGG carrying complete pilus loci seem to have highest IE potential in humans with significant links between SGG bacteremia/IE and underlying diseases including CRC. Other SBSEC host-microbe combinations might rely on currently unknown mechanisms. Comparative genome data of blood, commensal and food isolates are limited but required to elucidate the role of pili and other virulence factors, understand pathogenicity mechanisms, host specificity and estimate health risks for animals, humans and food alike.

Investigating the association between African spontaneously fermented dairy products, faecal carriage of Streptococcus infantarius subsp. infantarius and colorectal adenocarcinoma in Kenya

Consumption of traditional fermented dairy products (tFDP) in Africa leads to the ingestion of up to 108Streptococcus infantarius subspecies infantarius (Sii) per millilitre of spontaneously fermented milk. Sii is a member of the Streptococcus bovis/Streptococcus equinus complex (SBSEC) for which some members are associated particularly with colorectal cancer or endocarditis. The extent of health risks to tFDP consumers is largely unknown. A hospital-based unmatched case-control study was conducted at Kenyatta National Hospital, Nairobi (Kenya) on 80 cases and 193 controls that were selected exhaustively from patients attending colonoscopy at the hospital. Logistic regression models adjusted for age, sex and residency were used in the statistical analysis. Consumption of tFDP was not associated with CRC (odds ratio (OR) 1.4; 95% Confidence interval (CI) 0.7-2.7; p=0.34). Risk factors associated with CRC included age above 40 years, and consumption of processed meat and alcohol. Faecal carriage of Sii was significantly higher in persons with colon tumours and polyps compared to controls (8.4% vs 21.6%: OR: 4.6; CI 1.3-15.9). Patients with haemorrhoids represented an unexpected carrier group with significantly higher Sii faecal carriage (30.4%, CI: 17.7-45.8). Consumption of tFDP does not represent risk factors for CRC whereas Sii seems to be associated with CRC. However, there is urgent need to assess this finding also in the general population, investigate the causality of SBSEC, Sii and CRC as well as compare the phylogenetic, functional and genomic relationship between human and dairy Sii with regards to the ongoing application of Sii in FDP production.

Streptococcus gallolyticus subsp. gallolyticus endocarditis isolate interferes with coagulation and activates the contact system

Streptococcus gallolyticus subsp. gallolyticus, formerly classified as S. bovis biotype I, is an increasing cause of bacteremia and infective endocarditis in the elderly. The physiopathology of infective endocarditis is poorly understood and involves immune and coagulation systems. In this study, we found that S. gallolyticus subsp. gallolyticus activates the human contact system, which in turn has two consequences: cleavage of high-molecular-weight kininogen (HK) resulting in release of the potent pro-inflammatory peptide bradykinin, and initiation of the intrinsic pathway of coagulation. S. gallolyticus subsp. gallolyticus was found to bind and activate factors of the human contact system at its surface, leading to a significant prolongation of the intrinsic coagulation time and to the release of bradykinin. High-affinity binding of factor XII to the bacterial Pil1 collagen binding protein was demonstrated with a K_D of 13 nM. Of note, Pil1 expression was exclusively found in S. gallolyticus subsp. gallolyticus, further supporting an essential contribution of this pilus in virulence.

Bacterial diversity of the Colombian fermented milk "Suero Costeño" assessed by culturing and high-throughput sequencing and DGGE analysis of 16S rRNA gene amplicons

"Suero Costeño" (SC) is a traditional soured cream elaborated from raw milk in the Northern-Caribbean coast of Colombia. The natural microbiota that characterizes this popular Colombian fermented milk is unknown, although several culturing studies have previously been attempted. In this work, the microbiota associated with SC from three manufacturers in two regions, "Planeta Rica" (Córdoba) and "Caucasia" (Antioquia), was analysed by means of culturing methods in combination with high-throughput sequencing and DGGE analysis of 16S rRNA gene amplicons. The bacterial ecosystem of SC samples was revealed to be composed of lactic acid bacteria belonging to the Streptococcaceae and Lactobacillaceae families; the proportions and genera varying among manufacturers and region of elaboration. Members of the Lactobacillus acidophilus group, Lactocococcus lactis, Streptococcus infantarius and Streptococcus salivarius characterized this artisanal product. In comparison with culturing, the use of molecular in deep culture-independent techniques provides a more realistic picture of the overall bacterial communities residing in SC. Besides the descriptive purpose, these approaches will facilitate a rational strategy to follow (culture media and growing conditions) for the isolation of indigenous strains that allow standardization in the manufacture of SC.