Nutraceutical production with food-grade microorganisms

Bioactive Ingredients from Dairy-Based Lactic Acid Bacterial Fermentations for Functional Food Production and Their Health Effects

Lactic acid bacteria are traditionally applied in a variety of fermented food products, and they have the ability to produce a wide range of bioactive ingredients during fermentation, including vitamins, bacteriocins, bioactive peptides, and bioactive compounds. The bioactivity and health benefits associated with these ingredients have garnered interest in applications in the functional dairy market and have relevance both as components produced in situ and as functional additives. This review provides a brief description of the regulations regarding the functional food market in the European Union, as well as an overview of some of the functional dairy products currently available in the Irish and European markets. A better understanding of the production of these ingredients excreted by lactic acid bacteria can further drive the development and innovation of the continuously growing functional food market.

Chemical composition of extracts from leaves, stems and roots of wasabi (Eutrema japonicum) and their anti-cancer, anti-inflammatory and anti-microbial activities

The purpose of our study was to evaluate the composition of the extracts obtained from the roots and leaves of Eutrema japonicum cultivated in Poland. For this purpose, LC-DAD-IT-MS and LC-Q-TOF-MS analyses were used. The results revealed the presence of forty-two constituents comprising glycosinolates, phenylpropanoid glycosides, flavone glycosides, hydroxycinnamic acids, and other compounds. Then, the resultant extracts were subjected to an assessment of the potential cytotoxic effect on human colon adenocarcinoma cells, the effect on the growth of probiotic and intestinal pathogenic strains, as well as their anti-inflammatory activity. It was demonstrated that 60% ethanol extract from the biennial roots (WR2) had the strongest anti-inflammatory, antibacterial, and cytotoxic activities compared to the other samples. Our results suggest that extracts from E. japonicum may be considered as a promising compound for the production of health-promoting supplements.

Evaluation of the immunogenicity of auxotrophic Lactobacillus with CRISPR-Cas9D10A system-mediated chromosomal editing to express porcine rotavirus capsid protein VP4

Porcine rotavirus (PoRV) is an important pathogen, leading to the occurrence of viral diarrhoea . As the infection displays obvious enterotropism, intestinal mucosal immunity is the significant line of defence against pathogen invasion. Moreover, as lactic acid bacteria (LAB) show acid resistance, bile salt resistance and immune regulation, it is of great significance to develop an oral vaccine. Most traditional plasmid delivery vectors use antibiotic genes as selective markers, easily leading to antibiotic accumulation. Therefore, to select a food-grade marker in genetically engineering food-grade microorganisms is vital. Based on the CRISPR-Cas9D10A system, we constructed a stable auxotrophic Lactobacillus paracasei HLJ-27 (Lactobacillus △Alr HLJ-27) strain. In addition, as many plasmids replicate in the host bacteria, resulting in internal gene deletions. In this study,we used a temperature-sensitive gene editing plasmidto insert the VP4 gene into the genome, yielding the insertion mutant strains VP4/△Alr HLJ-27, VP4/△Alr W56, and VP4/W56. This recombinant bacterium efficiently induced secretory immunoglobulin A (SIgA)-based mucosal and immunoglobulin G (IgG)-based humoral immune responses. These oral mucosal vaccines have the potential to act as an alternative to the application of antibiotics in the future and induce efficient immune responses against PEDV infection.

First report on Vitamin B9 production including quantitative analysis of its vitamers in the yeast Scheffersomyces stipitis

Background

The demand for naturally derived products is continuously growing. Nutraceuticals such as pre- and post-biotics, antioxidants and vitamins are prominent examples in this scenario, but many of them are mainly produced by chemical synthesis. The global folate market is expected to register a CAGR of 5.3% from 2019 to 2024 and reach USD 1.02 billion by the end of 2024. Vitamin B9, commonly known as folate, is an essential micronutrient for humans. Acting as a cofactor in one-carbon transfer reactions, it is involved in many biochemical pathways, among which the synthesis of nucleotides and amino acids. In addition to plants, many microorganisms can naturally produce it, and this can pave the way for establishing production processes. In this work, we explored the use of Scheffersomyces stipitis for the production of natural vitamin B9 by microbial fermentation as a sustainable alternative to chemical synthesis.

Results

Glucose and xylose are the main sugars released during the pretreatment and hydrolysis processes of several residual lignocellulosic biomasses (such as corn stover, wheat straw or bagasse). We optimized the growth conditions in minimal medium formulated with these sugars and investigated the key role of oxygenation and nitrogen source on folate production. Vitamin B9 production was first assessed in shake flasks and then in bioreactor, obtaining a folate production up to 3.7 ± 0.07 mg/L, which to date is the highest found in literature when considering wild type microorganisms. Moreover, the production of folate was almost entirely shifted toward reduced vitamers, which are those metabolically active for humans.

Conclusions

For the first time, the non-Saccharomyces yeast S. stipitis was used to produce folate. The results confirm its potential as a microbial cell factory for folate production, which can be also improved both by genetic engineering strategies and by fine-tuning the fermentation conditions and nutrient requirements.

OUP accepted manuscript

Nowadays, the growing human population exacerbates the need for sustainable resources. Inspiration and achievements in nutrient production or human/animal health might emanate from microorganisms and their adaptive strategies. Here, we exemplify the benefits of lactic acid bacteria (LAB) for numerous biotechnological applications and showcase their natural transformability as a fast and robust method to hereditarily influence their phenotype/traits in fundamental and applied research contexts. We described the biogenesis of the transformation machinery and we analyzed the genome of hundreds of LAB strains exploitable for human needs to predict their transformation capabilities. Finally, we provide a stepwise rational path to stimulate and optimize natural transformation with standard and synthetic biology techniques. A comprehensive understanding of the molecular mechanisms driving natural transformation will facilitate and accelerate the improvement of bacteria with properties that serve broad societal interests.

The antagonistic activity of the synbiotic containing Lactobacillus acidophilus and pineapple residue FOS against pathogenic bacteria

Fructooligosaccharide is used widely in many foods and pharmaceutical industries and produced by using different ways such as extracting it from plants or producing it by using plants and microorganisms' enzymes. In a previous study, we extracted Fructosyltransferase (Ftase) enzyme from pineapple residue and produced FOS. In this study, we measured the antagonistic activity of two synbiotics, the first synbiotic containing Lactobacillus acidophilus and the produced FOS, the second synbiotic containing Lactobacillus acidophilus and standard FOS, against pathogenic bacteria (P. aeruginosa, E. coli, S. aureus and B cereus). The results showed that the antagonistic activity of both synbiotic types was very close, as there were no significant differences between them except in the antagonistic activity against S. aureus, there was a significant difference between the synbiotic containing the standard FOS, which was the highest in its antagonistic activity compared to the synbiotic containing the produced FOS in this study. The activity of the fructooligosaccharide (FOS) extracted from pineapple residue was evident in enhancing the activity of the probiotic bacteria (L. acidophilus), which had a major role in the production of acids and compounds that inhibited the pathogenic bacteria. The diameters of inhibition areas in the current study ranged between 19.33-28 mm, and E. coli was more susceptible to inhibition, followed by S. aureus, P. aeruginosa, and B. cereus, respectively.

Adaptive laboratory evolution of microbial co-cultures for improved metabolite secretion

Adaptive laboratory evolution has proven highly effective for obtaining microorganisms with enhanced capabilities. Yet, this method is inherently restricted to the traits that are positively linked to cell fitness, such as nutrient utilization. Here, we introduce coevolution of obligatory mutualistic communities for improving secretion of fitness‐costly metabolites through natural selection. In this strategy, metabolic cross‐feeding connects secretion of the target metabolite, despite its cost to the secretor, to the survival and proliferation of the entire community. We thus co‐evolved wild‐type lactic acid bacteria and engineered auxotrophic Saccharomyces cerevisiae in a synthetic growth medium leading to bacterial isolates with enhanced secretion of two B‐group vitamins, viz., riboflavin and folate. The increased production was specific to the targeted vitamin, and evident also in milk, a more complex nutrient environment that naturally contains vitamins. Genomic, proteomic and metabolomic analyses of the evolved lactic acid bacteria, in combination with flux balance analysis, showed altered metabolic regulation towards increased supply of the vitamin precursors. Together, our findings demonstrate how microbial metabolism adapts to mutualistic lifestyle through enhanced metabolite exchange.

Do Bioactive Food Compound with Avena sativa L., Linum usitatissimum L. and Glycine max L. Supplementation with Moringa oleifera Lam. Have a Role against Nutritional Disorders? An Overview of the In Vitro and In Vivo Evidence

Functional clinical nutrition is an integrative science; it uses dietary strategies, functional foods and medicinal plants, as well as combinations thereof. Both functional foods and medicinal plants, whether associated or not, form nutraceuticals, which can bring benefits to health, in addition to being included in the prevention and treatment of diseases. Some functional food effects from Avena sativa L. (oats), Linum usitatissimum L. (brown flaxseed), Glycine max L. (soya) and Moringa oleifera have been proposed for nutritional disorders through in vitro and in vivo tests. A formulation called a bioactive food compound (BFC) showed efficiency in the association of oats, flaxseed and soy for dyslipidemia and obesity. In this review, we discuss the effects of BFC in other nutritional disorders, as well as the beneficial effects of M. oleifera in obesity, cardiovascular disease, diabetes mellitus type 2, metabolic syndrome, intestinal inflammatory diseases/colorectal carcinogenesis and malnutrition. In addition, we hypothesized that a BFC enriched with M. oleifera could present a synergistic effect and play a potential benefit in nutritional disorders. The traditional consumption of M. oleifera preparations can allow associations with other formulations, such as BFC. These nutraceutical formulations can be easily accepted and can be used in sweet preparations (fruit and/or vegetable juices, fruit and/or vegetable vitamins, porridges, yogurt, cream, mousses or fruit salads, cakes and cookies) or savory (vegetable purees, soups, broths and various sauces), cooked or not. These formulations can be low-cost and easy-to-use. The association of bioactive food substances in dietary formulations can facilitate adherence to consumption and, thus, contribute to the planning of future nutritional interventions for the prevention and adjuvant treatment of the clinical conditions presented in this study. This can be extended to the general population. However, an investigation through clinical studies is needed to prove applicability in humans.

Physicochemical analysis, proteolysis activity and exopolysaccharides production of herbal yogurt fortified with plant extracts

Yogurt production with starter culture at 41 °C in the presence of plant water extracts (Momordica grosvenori, Psidium guajava, Lycium barbarum or Garcinia mangostana) were studied to examine the effects on acidification, physicochemical properties, microbial growth, proteolytic activity, and exopolysaccharide (EPS) content. All plant-based yogurt reached a pH of 4.5 faster (300–330 min) than plain-yogurt (360 min). All plant water extracts stimulated Lactobacillus spp. (∼7.4 log10 CFU/mL) and Streptococcus thermophilus (8.20–8.50 log10 CFU/mL) growth except for G. mangostana which marginally inhibited Lactobacillus spp. growth (7.21 log10 CFU/mL). M. grosvenori, L. barbarum, and G. mangonstana were significantly affected proteolysis of milk proteins (46.2 ± 0.8, 39.9 ± 0.5, & 35.8 ± 0.1 µg/mL; respectively) compared to plain-yogurt (26.3 ± 0.4 µg/mL). The presence of G. mangostana and L. barbarum resulted in an increase (p < 0.05) of total solids content (∼15.0%) and water holding capacity in yogurt (28.1 ± 1.2 & 26.5 ± 0.3%; respectively; p < 0.05). In addition, M. grosvenori water extract enhanced (p < 0.05) syneresis of yogurt (1.78 ± 0.30%). L. barbarum yogurt showed the highest EPS concentration (220.9 ± 12.4 µg/L) among yogurt samples. In conclusion, the presence of plant water extracts positively altered yogurt fermentation, enhanced proteolysis of milk protein, and induced EPS production.

Recombinant Lactococcus lactis NZ3900 expressing bioactive human FGF21 reduced body weight of Db/Db mice through the activity of brown adipose tissue

Fibroblast growth factor 21 (FGF21), a metabolism regulator, has an important effect on metabolic diseases, such as obesity and diabetes. It is also expressed in mice, and the murine source has high homology with human FGF21. Recently, it has been extensively studied and has become a potential drug target for the treatment of metabolic diseases. As it is a protein-based hormone, FGF21 cannot be easily and quickly absorbed into the blood through oral administration. Moreover, it has a 0-2 h half-life in vivo, as shown in a previous study, thus its efficacy lasts for a short period of time when used to treat metabolic diseases, limiting its clinical applications. To avoid these limitations, we used Lactococcus lactis, a food-grade bacterium, as the host to express FGF21. It could be used successfully for the expression and long-term effect of FGF21 in vivo. Instead of antibiotic resistance genes, the LacF gene was used as a selection marker in the NZ3900/PNZ8149 expression system, which is safe and could reduce the antibiotic resistance crisis. In this study, we a constructed human FGF21 expressing L. lactis strain and administered it to Db/Db mice by gavage. Compared with the control group, the body weight of mice in the experimental group was significantly reduced, and the overall homeostasis was improved in mice treated with human FGF21. Moreover, the activity of brown adipose tissue was enhanced. These results revealed that oral administration of FGF21 through heterologous expression in L. lactis appears to be an effective approach for its clinical application.

Microbial Metabolic Capacity for Intestinal Folate Production and Modulation of Host Folate Receptors

Microbial metabolites, including B complex vitamins contribute to diverse aspects of human health. Folate, or vitamin B9, refers to a broad category of biomolecules that include pterin, para-aminobenzoic acid (pABA), and glutamate subunits. Folates are required for DNA synthesis and epigenetic regulation. In addition to dietary nutrients, the gut microbiota has been recognized as a source of B complex vitamins, including folate. This study evaluated the predicted folate synthesis capabilities in the genomes of human commensal microbes identified in the Human Microbiome Project and folate production by representative strains of six human intestinal bacterial phyla. Bacterial folate synthesis genes were ubiquitous across 512 gastrointestinal reference genomes with 13% of the genomes containing all genes required for complete de novo folate synthesis. An additional 39% of the genomes had the genetic capacity to synthesize folates in the presence of pABA, an upstream intermediate that can be obtained through diet or from other intestinal microbes. Bacterial folate synthesis was assessed during exponential and stationary phase growth through the evaluation of expression of select folate synthesis genes, quantification of total folate production, and analysis of folate polyglutamylation. Increased expression of key folate synthesis genes was apparent in exponential phase, and increased folate polyglutamylation occurred during late stationary phase. Of the folate producers, we focused on the commensal Lactobacillus reuteri to examine host-microbe interactions in relation to folate and examined folate receptors in the physiologically relevant human enteroid model. RNAseq data revealed segment-specific folate receptor distribution. Treatment of human colonoid monolayers with conditioned media (CM) from wild-type L. reuteri did not influence the expression of key folate transporters proton-coupled folate transporter (PCFT) or reduced folate carrier (RFC). However, CM from L. reuteri containing a site-specific inactivation of the folC gene, which prevents the bacteria from synthesizing a polyglutamate tail on folate, significantly upregulated RFC expression. No effects were observed using L. reuteri with a site inactivation of folC2, which results in no folate production. This work sheds light on the contributions of microbial folate to overall folate status and mammalian host metabolism.

Biochemical Characterization of Heat-Tolerant Recombinant L-Arabinose Isomerase from Enterococcus faecium DBFIQ E36 Strain with Feasible Applications in D-Tagatose Production

D-Tagatose is a ketohexose, which presents unique properties as a low-calorie functional sweetener possessing a sweet flavor profile similar to D-sucrose and having no aftertaste. Considered a generally recognized as safe (GRAS) substance by FAO/WHO, D-tagatose can be used as an intermediate for the synthesis of other optically active compounds as well as an additive in detergent, cosmetic, and pharmaceutical formulations. This study reports important features for L-arabinose isomerase (EC 5.3.1.4) (L-AI) use in industry. We describe arabinose (araA) gene virulence analysis, gene isolation, sequencing, cloning, and heterologous overexpression of L-AI from the food-grade GRAS bacterium Enterococcus faecium DBFIQ E36 in Escherichia coli and assess biochemical properties of this recombinant enzyme. Recombinant L-AI (rL-AI) was one-step purified to homogeneity by Ni²⁺-agarose resin affinity chromatography and biochemical characterization revealed low identity with both thermophilic and mesophilic L-AIs but high degree of conservation in residues involved in substrate recognition. Optimal conditions for rL-AI activity were 50 °C, pH 5.5, and 0.3 mM Mn²⁺, exhibiting a low cofactor concentration requirement and an acidic optimum pH. Half-life at 45 °C and 50 °C were 1427 h and 11 h, respectively, and 21.5 h and 39.5 h at pH 4.5 and 5.6, respectively, showing the high stability of the enzyme in the presence of a metallic cofactor. Bioconversion yield for D-tagatose biosynthesis was 45% at 50 °C after 48 h. These properties highlight the technological potential of E. faecium rL-AI as biocatalyst for D-tagatose production.

Translation enhancement by a Dictyostelium gene sequence in Escherichia coli

Methods for heterologous protein production in Escherichia coli have revolutionized biotechnology and the bioindustry. It is ultimately important to increase the amount of protein product from bacteria. To this end, a variety of tools, such as effective promoters, have been developed. Here, we present a versatile molecular tool based on a phenomenon termed "translation enhancement by a Dictyostelium gene sequence" ("TED") in E. coli. We found that protein expression was increased when a gene sequence of Dictyostelium discoideum was placed upstream of the Shine-Dalgarno sequence located between the promoter and the initiation codon of a target gene. The most effective sequence among the genes examined was mlcR, which encodes the myosin regulatory light chain, a subunit of myosin II. Serial deletion analysis revealed that at least 10 bases of the 3' end of the mlcR gene enhanced the production of green fluorescent protein in cells. We applied this tool to a T7 expression system and found that the expression level of the proteins tested was increased when compared with the conventional method. Thus, current protein production systems can be improved by combination with TED.

Lactic acid bacteria as starter cultures: An update in their metabolism and genetics

Lactic acid bacteria (LAB) are members of an heterogenous group of bacteria which plays a significant role in a variety of fermentation processes. The general description of the bacteria included in the group is gram-positive, non-sporing, non-respiring cocci or rods. An overview of the genetics of lactococci, Streptococcus thermophilus, lactobacilli, pediococci, leuconostocs, enterococci and oenococciis presented with special reference to their metabolic traits. The three main pathways in which LAB are involved in the manufacture of fermented foods and the development of their flavour, are (a) glycolysis (fermentation of sugars), (b) lipolysis (degradation of fat) and (c) proteolysis (degradation of proteins). Although the major metabolic action is the production of lactic acid from the fermentation of carbohydrates, that is, the acidification of the food, LAB are involved in the production of many beneficial compounds such as organic acids, polyols, exopolysaccharides and antimicrobial compounds, and thus have a great number of applications in the food industry (i.e. starter cultures). With the advances in the genetics, molecular biology, physiology, and biochemistry and the reveal and publication of the complete genome sequence of a great number of LAB, new insights and applications for these bacteria have appeared and a variety of commercial starter, functional, bio-protective and probiotic cultures with desirable properties have marketed.

Probiotics in human health and disease: from nutribiotics to pharmabiotics

Probiotics are the most useful tools for balancing the gut microbiota and thereby influencing human health and disease. Probiotics have a range of effects, from those on nutritional status to medical conditions throughout the body from the gut to non-intestinal body sites such as the brain and skin. Research interest in probiotics with nutritive claims (categorized as nutribiotics) has evolved into interest in therapeutic and pharmacological probiotics with health claims (pharmabiotics). The concept of pharmabiotics emerged only two decades ago, and the new categorization of probiotics to nutribiotics and pharmabiotics was recently suggested, which are under the different regulation depending on that they are food or drug. Information of the gut microbiome has been continuously accumulating, which will make possible the gut microbiome-based healthcare in the future, when nutribiotics show potential for maintaining health while pharmabiotics are effective therapeutic tools for human diseases. This review describes the current understanding in the conceptualization and classification of probiotics. Here, we reviewed probiotics as nutribiotics with nutritional functions and pharmabiotics with pharmaceutic functions in different diseases.

Tiny but mighty: bacterial membrane vesicles in food biotechnological applications

Membrane vesicle (MV) production is observed in all domains of life. Evidence of MV production accumulated in recent years among bacterial species involved in fermentation processes. These studies revealed MV composition, biological functions and properties, which made us recognize the potential of MVs in food applications as delivery vehicles of various compounds to other bacteria or the human host. Moreover, MV producing strains can deliver benefits as probiotics or starters in fermentation processes. Next to the natural production of MVs, we also highlight possible methods for artificial generation of bacterial MVs and cargo loading to enhance their applicability. We believe that a more in-depth understanding of bacterial MVs opens new avenues for their exploitation in biotechnological applications.

Sub-inhibitory concentrations of gentamicin triggers the expression of aac(6')Ie-aph(2″)Ia, chaperons and biofilm related genes in Lactobacillus plantarum MCC 3011

The study aimed to analyze the effects of sub-inhibitory concentrations of gentamicin on the expressions of high level aminoglycoside resistant (HLAR) bifunctional aac(6')Ie-aph(2″)Ia, biofilm and chaperone genes in Lactobacillus plantarum. The analysis of the biofilm formation in five isolates obtained from chicken sausages indicated their role in exhibiting phenotypic resistance based on the varied MIC values despite carrying the bifunctional gene. The biofilm formation significantly increased when L. plantarum MCC 3011 was grown in sub-inhibitory concentrations of gentamicin (4 μg/ml), kanamycin (8 μg/ml) and streptomycin (2 μg/ml). Thirty day gentamicin selection increased minimum inhibitory concentration (MIC) values from 4 to 64 and 2 to 256 fold for gentamicin and kanamycin, respectively when compared to the parental cultures. Expression studies revealed that constant exposure to gentamicin had induced chaperon [groEL] and the bifunctional gene, aac(6')Ie-aph(2″)Ia upto nine fold. Induction of groEL, groES and lamC genes in gentamicin (4 μg/ml) preincubated MCC 3011 indicated their significant role in aminoglycoside mediated response. Our study indicates that constant exposure to sub inhibitory concentrations of gentamicin allows L. plantarum to adapt against higher doses of aminoglycosides. This highlights the risks and food safety issues associated with the use of aminoglycosides in livestock and consumption of farm oriented fermented food products.

The Use of Starter Cultures in Traditional Meat Products

Starter cultures could play an essential role in the manufacture of traditional cured meat products. In order to achieve objectives related to meat products’ quality and safety improvement, the selection of particular strains constituting a starter culture should be carried out in the context of its application, since its functionality will depend on the type of sausage and process conditions. Also, strain selection should comply with particular requirements to warrant safety. The aim of the current review is to update the knowledge on the use of starter cultures in traditional meat products, with focus on dry-fermented products. In this manuscript, we will try to give answers to some relevant questions: Which starter cultures are used and why? Why are LAB used? What are their role and their specific mode of action? Which other groups of microorganisms (bacteria and fungi) are used as starter cultures and how do they act? A particular revision of omics approach regarding starter cultures is made since the use of these techniques allows rapid screening of promising wild strains with desirable functional characteristics, enabling the development of starter cultures better adapted to the meat matrix.

Techno-functional differentiation of two vitamin B12 producing Lactobacillus plantarum strains: an elucidation for diverse future use

An appropriate selection of Lactobacillus strain (probiotic/starter/functional) on the basis of its techno-functional characteristics is required before developing a novel fermented functional food. We compared vitamin B₁₂ (B₁₂, cobalamin) producing Lactobacillus plantarum isolates, BHM10 and BCF20, for functional (vitamin over-production, genomic insight to B₁₂ structural genes, and probiotic attributes) and technological [milks (skim and soy) fermentation and B₁₂ bio-fortification] characteristics. Addition of B₁₂ precursors (5-amonolevulinate and dimethylbenzimidazole) to cobalamin-free fermentation medium increased vitamin production in BHM10, BCF20, and DSM20016 (a positive standard) by 3.4-, 4.4-, and 3.86-folds, respectively. Three important B₁₂ structural genes were detected in L. plantarum species (strains BHM10 and BCF20) by PCR for the first time. The gene sequences were submitted to NCBI GenBank and found phylogenetically closer to respective sequences in B₁₂ producing Lactobacillus reuteri strains. During comparative probiotic testing, BCF20 showed significantly higher (p < 0.05 to p < 0.001) gastrointestinal tolerance and cell surface hydrophobicity (p < 0.05) than BHM10. Moreover, only BCF20 was found positive for BSH activity and also exhibited comparatively better antagonistic potential against potent pathogens. Conversely, high acid and bile susceptible strain BHM10 displayed significantly higher soy milk fermentation and resultant B₁₂ bio-fortification abilities during technological testing. Two B₁₂ quantification techniques, UFLC and competitive immunoassay, confirmed the in vitro and in situ bio-production of bio-available form of B₁₂ after BHM10 fermentation. Conclusively, techno-functional differentiation of two B₁₂ producing strains elucidates their diverse future use; BCF20 either for B₁₂ over-production (in vitro) or as a probiotic candidate, while BHM10 for cobalamin bio-fortification (in situ) in soy milk.

Cobalamin production by Lactobacillus coryniformis: biochemical identification of the synthetized corrinoid and genomic analysis of the biosynthetic cluster

Background

Despite the fact that most vitamins are present in a variety of foods, malnutrition, unbalanced diets or insufficient intake of foods are still the cause of vitamin deficiencies in humans in some countries. Vitamin B₁₂ (Cobalamin) is a complex compound that is only naturally produced by bacteria and archea. It has been reported that certain strains belonging to lactic acid bacteria group are capable of synthesized water-soluble vitamins such as those included in the B-group, as vitamin B₁₂. In this context, the goal of the present paper was to evaluate and characterize the production of vitamin B₁₂ in Lactobacillus coryniformis CRL 1001, a heterofermentative strain isolated from silage.

Results

Cell extract of L. coryniformis CRL 1001, isolated from silage, is able to correct the coenzyme B₁₂ requirement of Salmonella enterica serovar Typhimurium AR 2680 in minimal medium. The chemical characterization of the corrinoid-like molecule isolated from CRL 1001 cell extract using HPLC and mass spectrometry is reported. The majority of the corrinoid produced by this strain has adenine like Coα-ligand instead 5,6-dimethylbenzimidazole. Genomic studies revealed the presence of the complete machinery of the anaerobic biosynthesis pathway of coenzyme B₁₂. The detected genes encode all proteins for the corrin ring biosynthesis and for the binding of upper (β) and lower (α) ligands in one continuous stretch of the chromosome.

Conclusions

The results here described show for the first time that L. coryniformis subsp. coryniformis CRL 1001 is able to produce pseudocobalamin containing adenine instead of 5,6-dimethlbenzimidazole in the Coα-ligand. Genomic analysis allowed the identification and characterization of the complete de novo biosynthetic pathway of the corrinoid produced by the CRL 1001 strain.

Fermented Milks Fortified with B-group Vitamins: Vitamin Stability and Effect on Resulting Products

Four fermented milks were made from cow's milk fortified with B-group vitamins (thiamine (B1), riboflavin (B2), pyridoxine, pyridoxal, pyridoxamine and folic acid) inoculated with different mixed probiotic cultures. Fermented milks made from non-fortified milk were used as controls. Some vitamins were partly lost during heating of the milk and fermentation but the level of all vitamins remained stable during storage for 16 days at 4°C. Species and strain of the culture were clearly found to affect the vitamin level throughout fermentation and storage of the products. Fortification was observed as having no impact on the composition or sensory properties of the products, attributes that were found to be mainly dependent on the culture. At the fortification level applied, fermented products could be a good alternative to dietary supplements, because they are readily consumed and combine the beneficial effects of probiotic microorganisms with important amounts of valuable vitamins.

Development of GRAS strains for nutraceutical production using systems and synthetic biology approaches: advances and prospects

Nutraceuticals are food substances with medical and health benefits for humans. Limited by complicated procedures, high cost, low yield, insufficient raw materials, resource waste, and environment pollution, chemical synthesis and extraction are being replaced by microbial synthesis of nutraceuticals. Many microbial strains that are generally regarded as safe (GRAS) have been identified and developed for the synthesis of nutraceuticals, and significant nutraceutical production by these strains has been achieved. In this review, we systematically summarize recent advances in nutraceutical research in terms of physiological effects on health, potential applications, drawbacks of traditional production processes, characteristics of production strains, and progress in microbial fermentation. Recent advances in systems and synthetic biology techniques have enabled comprehensive understanding of GRAS strains and its wider applications. Thus, these microbial strains are promising cell factories for the commercial production of nutraceuticals.

Physicochemical characterization of exopolysaccharides produced by Lactobacillus rhamnosus on various carbon sources

The impact of five carbohydrate sources (glucose, maltose, galactose, sucrose, and lactose) on the chemical composition, structure, morphology, and physicochemical properties, as well as, viscosity of exopolysaccharides (EPSs) produced by Lactobacillus rhamnosus E/N was investigated. GLC-MS analysis and 2DNMR spectroscopy showed that the EPSs had the same primary structure independently of the carbon source used in the growth medium. The following EPS composition was elucidated: four rhamnose, two glucose, and one galactose residue with a pyruvate substituent. Molecular masses (M(w)) were determined by gel permeation chromatography, which revealed differences in M(w) distribution. EPS-Gal, EPS-Suc, and EPS-Lac showed heterogenic fractions of a high and low molecular weight, while EPS-Mal and EPS-Glc contained only a high-molecular-weight fraction. AFM microscopy revealed morphological differences in chain length, thickness, and branching. Differences in the Mw ratio and thickness of the polymer chain were correlated with high viscosity of EPS solutions. Our results indicate that a single bacterial strain, depending on the carbon source in the medium, can produce EPSs of different rheological properties.

Identification of bioactive metabolites dihydrocanadensolide, Kojic acid, and vanillic acid in soy sauce using GC-MS, NMR spectroscopy, and single-crystal X-ray diffraction

Microbial transformations of intrinsic substrates offer immense potential for generating new bioactive compounds in fermented food products. The aim of this work was to characterize the secondary metabolites in soy sauce, one of the oldest fermented condiments. Ethyl acetate extract (EAE) of soy sauce was separated using flash column chromatography, crystallized, and analyzed by nuclear magnetic resonance (NMR), single-crystal X-ray diffraction (SC-XRD), and mass spectroscopy. Dihydrocanadensolide (DHC), an antiulcer agent, was identified in a food for the first time. The natural stereostructure of DHC, which remained controversial for several decades, was determined as (3S,3aS,6R,6aR)-6-butyl-3-methyltetrahydrofuro[3,4-b]furan-2,4-dione using SC-XRD analysis. Kojic acid (KA) and vanillic acid (VA) were also identified from EAE as bioactive metabolic products of fungi and yeasts. Moreover, a new polymorphic form of KA was determined by SC-XRD.

Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products

Wheat contains various essential nutrients including the B group of vitamins. However, B group vitamins, normally present in cereals-derived products, are easily removed or destroyed during milling, food processing or cooking. Lactic acid bacteria (LAB) are widely used as starter cultures for the fermentation of a large variety of foods and can improve the safety, shelf life, nutritional value, flavor and overall quality of the fermented products. In this regard, the identification and application of strains delivering health-promoting compounds is a fascinating field. Besides their key role in food fermentations, several LAB found in the gastrointestinal tract of humans and animals are commercially used as probiotics and possess generally recognized as safe status. LAB are usually auxotrophic for several vitamins although certain strains of LAB have the capability to synthesize water-soluble vitamins such as those included in the B group. In recent years, a number of biotechnological processes have been explored to perform a more economical and sustainable vitamin production than that obtained via chemical synthesis. This review article will briefly report the current knowledge on lactic acid bacteria synthesis of vitamins B2, B11 and B12 and the potential strategies to increase B-group vitamin content in cereals-based products, where vitamins-producing LAB have been leading to the elaboration of novel fermented functional foods. In addition, the use of genetic strategies to increase vitamin production or to create novel vitamin-producing strains will be also discussed.

B-group vitamin production by lactic acid bacteria--current knowledge and potential applications

Although most vitamins are present in a variety of foods, human vitamin deficiencies still occur in many countries, mainly because of malnutrition not only as a result of insufficient food intake but also because of unbalanced diets. Even though most lactic acid bacteria (LAB) are auxotrophic for several vitamins, it is now known that certain strains have the capability to synthesize water-soluble vitamins such as those included in the B-group (folates, riboflavin and vitamin B(12) amongst others). This review article will show the current knowledge of vitamin biosynthesis by LAB and show how the proper selection of starter cultures and probiotic strains could be useful in preventing clinical and subclinical vitamin deficiencies. Here, several examples will be presented where vitamin-producing LAB led to the elaboration of novel fermented foods with increased and bioavailable vitamins. In addition, the use of genetic engineering strategies to increase vitamin production or to create novel vitamin-producing strains will also be discussed. This review will show that the use of vitamin-producing LAB could be a cost-effective alternative to current vitamin fortification programmes and be useful in the elaboration of novel vitamin-enriched products.

Food-grade gene expression in lactic acid bacteria

In the 1990s, significant efforts were invested in the research and development of food-grade expression systems in lactic acid bacteria (LAB). At this time, Lactococcus lactis in particular was demonstrated to be an ideal cell factory for the food-grade production of recombinant proteins. Steady progress has since been made in research on LAB, including Lactococcus, Lactobacillus and Streptococcus, in the areas of recombinant enzyme production, industrial food fermentation, and gene and metabolic pathway regulation. Over the past decade, this work has also led to new approaches on chromosomal integration vectors and host/vector systems. These newly constructed food-grade gene expression systems were designed with specific attention to self-cloning strategies, food-grade selection markers, plasmid replication and chromosomal gene replacements. In this review, we discuss some well-characterized chromosomal integration and food-grade host/vector systems used in LAB, with a special focus on sustainability, stability and overall safety, and give some attractive examples of protein expression that are based on these systems.