Application Of Lactic Acid Bacteria Research Articles

LACTIC ACID BACTERIA CONTRIBUTING TO UPGRADE FODDER QUALITY

A solid nutrition stock lays the basis for contemporary animal husbandry. Application of lactic acid bacteria and their metabolites to raise the standards of feed rations as ingredients of pre- and probiotic additives, is an evolutionarily grounded basic microecological technique to uphold health status and realize genetic potential of superproductive farm animals. Throughout several decades the studies are under way at the Institute of Microbiology of the National Academy of Sciences of Belarus on isolation of lactic acid bacterial strains from various natural sources, investigation of their properties, characterization of produced bioactive agents and elaboration of the derived technologies of manufacturing diverse microbial preparations for various purposes. Specially selected lactic acid bacteria isolated from various plant sources in Belarus and adapted to local ecological environment are distinguished by intense growth, capacity to compete with other microbial species, active acidogenesis, rapid acidification of substrates down to pH 4.2 or even lower, acid resistance, a broad spectrum of fermented carbohydrates (ability to utilize hexoses, pentoses, oligo- and polysaccharides) and they served as appropriate constituents of liquid biocompositions (Lacsil, Lacsil-M), dry preparation Lacsil-MS designed to improve quality of ensiled vegetable materials. Lacsil-MS2 concentrate includes homo- and heterofermentative lactic acid bacteria consuming a wide range of carbohydrates: hexoses, pentoses, oligo- and polysaccharides, including major reserve polysaccharides of cereals and legume grasses (starch, polyfructosides). Supply of fastly growing coccoid forms of lactic acid bacteria enables to intensify the process of lactic acid fermentation at the earliest stages and swiftly reduce pH of vegetable mass. Addition of strains with elevated antagonistic activity ensures the suppression of growth of microorganisms responsible for spoilage of fodder. Upgrading consortium composition with heterofermentative lactic acid bacteria and propionic acid bacteria prevents spoilage of fodder caused by air access in the course of feeding procedure. Production by the selected microbial cultures of a set of enzymes (amylase, α-galactosidase, β-glucanase, pectinase, etc.) capable to hydrolyze hardly digestible oligosaccharides, starch-containing and non-starchy polysaccharides of plant substrates, promotes enhanced bioaccess, better assimilation, increased alimentary and energy value of feed rations. Evaluation of technology of producing feed additive based on lactic acid bacteria possessing high α-galactosidase activity acquired top relevance due to the need to eliminate deficit of fodder protein in farm rations by replenishing the share of legumes (alfalfa, lupine, soy, peas, etc.). Introduction of such feed additive incorporating lactic acid bacteria, fermenting recalcitrant oligo- and polysaccharides with α(1→6) glycoside bonds allows to raise digestibility and assimilation of proteins and carbohydrates, to increase the input ratio of legume components into composite fodder formulas, to rule out intestinal disorders (gut meteorism), contributing thereby to farm stock productivity. It was found that application of preparations comprising selected lactic acid bacteria resulted in economy of fodder expense up to 20% per each kilo of live weight increment, to augment average daily body gains by 9-12%, to increase productivity of lactating cows by 5-10%, and to diminish by 5.0% losses of digestible protein as compared with imported product analogues.

Lactic Acid Bacteria-Gut-Microbiota-Mediated Intervention towards Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), arises from intricate interactions involving genetics, environment, and pharmaceuticals with an ambiguous pathogenic mechanism. Recently, there has been an increasing utilization of lactic acid bacteria (LAB) in managing IBD, attributed to their ability to enhance intestinal barrier function, mitigate inflammatory responses, and modulate gut microbiota. This review initiates by elucidating the pathogenesis of IBD and its determinants, followed by an exploration of the mechanisms underlying LAB therapy in UC and CD. Special attention is directed towards their influence on intestinal barrier function and homeostasis regulated by gut microbiota. Furthermore, the review investigates the complex interplay among pivotal gut microbiota, metabolites, and pathways associated with inflammation. Moreover, it underscores the limitations of LAB in treating IBD, particularly in light of their varying roles in UC and CD. This comprehensive analysis endeavors to offer insights for the optimized application of LAB in IBD therapy.

Isolation and screening of high biofilm producing lactic acid bacteria, and exploration of its effects on the microbial hazard in corn straw silage

Silage is a well-established method for preserving feed. However, the preparation process still poses several potential microbial hazards. Lactic acid bacteria exhibiting a biofilm phenotype are considered the most advanced 'fourth-generation probiotics' due to their significant potential in enhancing fermentation quality. In this study, a strain of high-biofilm-producing lactic acid bacteria (HBP-LAB) was successfully isolated from silage samples using the crystal violet method and designated as Lactiplantibacillus plantarum S23Y. This strain was subsequently used as an inoculant in corn straw for experimental purposes. The results indicated that it effectively reduced dry matter loss caused by microorganisms, thereby enhancing the retention of dry matter in silage. Following aerobic exposure, this strain was able to maintain the population of Lactobacillus and the concentration of lactic acid, which significantly decreased the likelihood of yeast-induced aerobic spoilage and improved the aerobic stability of the silage. However, it is important to note that this HBP-LAB did not have a significant impact on antibiotic resistance genes (ARGs) or mobile genetic elements (MGEs) in the silage. In conclusion, using S23Y as a representative strain, we have demonstrated that HBP-LAB can enhance the fermentation quality of silage to a certain extent and mitigate the detrimental effects of microorganisms. The findings of this study provide valuable insights for the application of lactic acid bacteria with a biofilm phenotype in silage fermentation.

Untargeted Metabolomics Analysis of Lactic Acid Bacteria Fermented Acanthopanax senticosus with Regard to Regulated Gut Microbiota in Mice.

Previous studies have shown that Acanthopanax senticosus (AS) has a beneficial preventive and therapeutic effect on colitis. The fermentation of lactic acid bacteria (LAB) can alter the efficacy of AS by modifying or producing new compounds with potential bioactive properties. However, the specific components and mechanisms that enhance the efficacy are still unclear. In the present experiment, untargeted metabolomics was used to analyze the changes in active components before and after LAB fermentation of AS. The aim was to explain the mechanism of AS fermentation in treating colitis using a colitis model in mice. The results indicated that the fermentation of LAB could enhance the levels of total flavonoids and total polyphenols in FAS. Additionally, the beneficial components such as Delphinidin chloride, Diosmetin, Psoralidin, and Catechol significantly increased (p < 0.05). The colitis treatment experiment demonstrated that fermented AS could alleviate symptoms and improve the morphology of colitis in mice by enhancing antioxidant enzymes like CAT, T-SOD, and T-AOC. It also regulated the composition and abundance of intestinal flora species, such as Lactobacillus and Pseudogracilibacillus. The effectiveness of fermented AS was significantly superior to that of unfermented AS (p < 0.05). In conclusion, this study contributes to the application of lactic acid bacteria in AS fermentation and reveals the mechanism of fermentation AS for colitis.

Physicochemical and organoleptic changes in goat’s milk cheddar cheese with the addition of Lactobacillus casei as a starter during ripening

Abstract The fermentation process using lactic acid bacteria (LAB) in cheese manufacturing plays important roles to enhance the nutritional content of cheese. This study aims to observe the effect of the addition of Lactobacillus casei in goat’s milk cheese manufacturing. Changes in physicochemical and organoleptic characteristics were observed during cheese ripening. Cheese was made using 8% of L. casei as starter and its changes were observed for 8 weeks of ripening. The results showed that the acidification process in cheese by L. casei resulted in a yield value of 10.85%. The ripening period affects significant changes in physical and chemical indicators, except for pH. Observations during cheese ripening from the 4th to the 8th week indicate that pH tends to stabilize at pH 5, protein increases by approximately 16%, and the decrease in moisture and fat content was by 18% and 15%, respectively. The best quality of cheese was obtained by 8 weeks of ripening. After 8 weeks of ripening, the cheese was yellow in color, has a hard texture with cheesy aroma, sour taste, and contains approximately 1.8 × 106 CFU/ml of LAB. The study of LAB application in goat’s milk cheddar cheese will provide an innovation in cheese production.

Evaluation of the performance of a three-strains lactic acid bacteria cocktail for the control of Listeria monocytogenes on marinated lean pork

The aim of this study was to evaluate the addition of a cocktail of three lactic acid bacteria (LAB) (Lactococcus lactis, Lacticaseibacillus paracasei and Lactiplantibacillus plantarum) as a protective culture into marinated pork. The pork was artificially inoculated with two Listeria monocytogenes strains and stored for 12 days. Two packagings were used: vacuum or modified atmosphere packaging (MAP). LAB, L. monocytogenes, psychrotrophic bacteria, pH, aw, color, the metataxonomic profile and the sensorial quality of the product were evaluated. The growth of L. monocytogenes under vacuum and MAP was reduced with the use of the LAB up to 0.8 and 0.7 log10 CFU/g, respectively. LAB counts gradually increased, which was accompanied by a slight decrease in pH. In LAB samples, psychrotrophic bacteria showed a reduction at day 12 as compared to non-inoculated samples. Some minor differences were also observed among samples for color and sensory parameters. Regardless of the type of packaging, the microbiota of the marinated pork was dominated initially by Photobacterium and subsequently during storage by a diversity of LAB. The application of LAB could help to obtain a safe product, although further evaluation would be required to optimize the application of the LAB cocktail in real-scale commercial scenarios.

Lactic Acid Bacteria in Sustainable Food Production

The main tenets of the sustainable food production model are to reduce the adverse environmental impacts of production and to use available resources more efficiently. The sustainable food production model allows companies to adapt their strategies to current challenges and requirements while maintaining long-term production stability and competitiveness. To ensure that sustainable food chain participants implement appropriate practices, research is being conducted to develop new solutions. Among the important issues that are of great interest to researchers is the use of lactic acid bacteria (LAB). These bacteria play a pivotal role in sustainable food production, encompassing environmental, economic, and social aspects. The following article highlights recent innovations and advancements in LAB applications, contributing to enhanced efficiency and sustainable development of food products. By fermenting food, LAB effectively enhances food safety, prolong shelf life, and augment nutritional values, while simultaneously eliminating or outcompeting foodborne pathogens, thus preventing food poisoning. This article underscores these often-overlooked aspects of LAB, such as the critical role of fermented food in sustaining humanity during challenging times, by providing essential nutrients, and supporting health through its unique preservative and probiotic properties. It also points out the lesser-known applications of these microorganisms, including the degradation of organic waste or biogas and bioplastics production.

Lactic Acid Bacteria As Biological Control Agent For Controlling Aspergillus Growth and Aflatoxin Production: A Review

Abstract: Aspergillus sp., a ubiquitous filamentous fungus, poses significant challenges to the food industry as a common spoilage and mycotoxin producing organism. The conventional use of chemical preservatives to control Aspergillus contamination raises concerns about potential health risks and environmental impacts. Therefore, alternative approaches, such as the utilization of natural biopreservatives, as inexpensive, safe, and promising mycotoxin decontamination strategies are being explored. Lactic acid bacteria have gained considerable attention as potential candidates due to their antimicrobial properties and long-standing safe use in food fermentation. This review provides a thorough summary of the potential of lactic acid bacteria as biopreservatives against Aspergillus sp. The inhibitory mechanisms of lactic acid bacteria against the proliferation of Aspergillus and mycotoxin yield are explored, highlighting the role of organic acids, antimicrobial peptides, and other bioactive compounds. The versatile application of lactic acid bacteria based natural preservatives across a range of food matrices, storage conditions, etc. is also addressed. Further research is warranted to optimize lactic acid bacteria strains, explore synergistic combinations, and investigate their efficacy in real food systems. Implementing lactic acid bacteria based biopreservative strategies could significantly enhance food safety and quality by reducing Aspergillus contamination and mycotoxin risks.

Effects of lactic acid bacteria inoculants on the nutrient composition, fermentation quality, and microbial diversity of whole-plant soybean-corn mixed silage.

The mixture of whole-plant soybean and whole-plant corn silage (WPSCS) is nutrient balanced and is also a promising roughage for ruminants. However, few studies have investigated the changes in bacterial community succession in WPSCS inoculated with homofermentative and heterofermentative lactic acid bacteria (LAB) and whether WPSCS inoculated with LAB can improve fermentation quality by reducing nutrient losses. This study investigated the effect of Lactobacillus plantarum (L. plantarum) or Lactobacillus buchneri (L. buchneri) on the fermentation quality, aerobic stability, and bacterial community of WPSCS. A 40:60 ratio of whole-plant soybean corn was inoculated without (CK) or with L. plantarum (LP), L. buchneri (LB), and a mixture of LP and LB (LPB), and fermented for 14, 28, and 56 days, followed by 7 days of aerobic exposure. The 56-day silage results indicated that the dry matter content of the LP and LB groups reached 37.36 and 36.67%, respectively, which was much greater than that of the CK group (36.05%). The pH values of the LP, LB, and LPB groups were significantly lower than those of the CK group (p < 0.05). The ammoniacal nitrogen content of LB was significantly lower than that of the other three groups (p < 0.05), and the ammoniacal nitrogen content of LP and LPB was significantly lower than that of CK (p < 0.05). The acetic acid content and aerobic stability of the LB group were significantly greater than those of the CK, LP, and LPB groups (p < 0.05). High-throughput sequencing revealed a dominant bacteria shift from Proteobacteria in fresh forage to Firmicutes in silage at the phylum level. Lactobacillus remained the dominant genus in all silage. Linear discriminant analysis effect size (LEFSe) analysis identified Lactobacillus as relatively abundant in LP-treated silage and Weissella in LB-treated groups. The results of KEGG pathway analysis of the 16S rRNA gene of the silage microbial flora showed that the abundance of genes related to amino acid metabolism in the LP, LB, and LPB groups was lower than that in the CK group (p < 0.05). In conclusion, LAB application can improve the fermentation quality and nutritional value of WPSCS by regulating the succession of microbial communities and metabolic pathways during ensiling. Concurrently, the LB inoculant showed the potential to improve the aerobic stability of WPSCS.

Multifaceted applications of lactic acid bacteria: From food preservation to mental health enhancement

Lactic acid bacteria (LAB) are beneficial microorganisms with capability to produce various functional inhibitory compounds which includes bacteriocins, organic acids, fatty acids, enzymes and other chemical substances that exhibit inhibitory effects on certain harmful microorganisms. Therefore, LAB is often found in fermented food which adds value to the nutritional composition of the food, and thereby offers a range of health benefits to human beings upon consumption. This review explores the diverse applications of LAB, focusing on their role in enhancing food safety, contributing to nutritional well-being, and their emerging significance in mental health as psychobiotics, specifically to tackle depression. The paper synthesises current research and advancements in LAB applications, providing insights into their potential in addressing contemporary health and nutritional challenges.

Fish-derived lactic acid bacteria supplementation enhanced the immunity and resistance in Crucian carp (Carassius auratus)

This study attempted to evaluate the potential for biofilm formation and the probiotic properties of lactic acid bacteria (LAB) isolated from the Carassius auratus intestine and to determine their antibacterial activity against crucial injurious bacteria of fish. The biological features test was carried out to obtain LAB with well-resistant pH, trypsin, bile and antibiotic challenge, and biofilm formation capacity. The most promising LAB isolates, y11 and y78 were identified as Lactobacillus johnsonii and Weissella confusa using 16S ribosomal RNA gene sequencing. We discovered that oral LAB additives improved immunity in the C. auratus by increasing immune-related expression of immunoglobulin M (IgM), superoxide dismutase (SOD), alkaline phosphatase (AKP), and lysozyme (LYS) in serum and interleukins (IL-10 and IL-1β), interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) in organs. After the introduction of Aeromonas veronii TH0426 for 15 days, the survival rate of C. auratus was determined as follows: the protection rate of group y11 was 45 %, and group y78 was 65 % when challenged with 109 CFU/mL density. This experiment successfully selected two LAB strains as the bioprotective agents and provided theoretical support for further LAB application in aquaculture.

Influence of lactic acid fermentation on the phenolic profile, antioxidant activities, and volatile compounds of black chokeberry (Aronia melanocarpa) juice.

Lactic acid fermentation is an effective method for improving the quality of black chokeberry. This study aimed to investigate the influence of lactic acid bacteria on the phenolic profile, antioxidant activities, and volatiles of black chokeberry juice. Initially, 107 cfu/mL of Lactiplantibacillus plantarum, Lactobacillus acidophilus, and Lacticaseibacillus rhamnosus were inoculated into pasteurized black chokeberry juice and fermented for 48h at 37°C. All these strains enhanced the total phenolic and total flavonoid contents, with La. acidophilus showing the highest total phenolic (1683.64mg/L) and total flavonoid (659.27mg/L) contents. Phenolic acids, flavonoids, and anthocyanins were identified using ultrahigh-performance liquid chromatography-tandem mass spectrometry. The prevalent phenolic acid, flavonoid, and anthocyanin in the lactic-acid-fermented black chokeberry juice were cinnamic acid, rutin, and cyanidin-3-O-rutinoside, respectively. Furthermore, following fermentation, the DPPH and ABTS scavenging capacity, as well as the reducing power capacity, increased from 59.98% to 92.70%, 83.06% to 94.95%, and 1.24 to 1.82, respectively. Pearson's correlation analysis revealed that the transformation of phenolic acids, flavonoids, and anthocyanins probably contributed to enhancing antioxidant activities and color conversation in black chokeberry juice. A total of 40 volatiles were detected in the fermented black chokeberry juice by gas chromatography-ion mobility spectrometry. The off-flavor odors, such as 1-penten-3-one and propanal in the black chokeberry juice, were weakened after fermentation. The content of 2-pentanone significantly increased in all fermented juice, imparting an ethereal flavor. Hence, lactic acid fermentation can effectively enhance black chokeberry products' flavor and prebiotic value, offering valuable insights into their production. PRACTICAL APPLICATION: The application of lactic acid bacteria in black chokeberry juice not only enhances its flavor but also improves its health benefits. This study has expanded the range of black chokeberry products and offers a new perspective for the development of the black chokeberry industry.

Roles of flavoprotein oxidase and the exogenous heme- and quinone-dependent respiratory chain in lactic acid bacteria.

Lactic acid bacteria (LAB) are a type of bacteria that convert carbohydrates into lactate through fermentation metabolism. While LAB mainly acquire energy through this anaerobic process, they also have oxygen-consuming systems, one of which is flavoprotein oxidase and the other is exogenous heme- or heme- and quinone-dependent respiratory metabolism. Over the past two decades, research has contributed to the understanding of the roles of these oxidase machineries, confirming their suspected roles and uncovering novel functions. This review presents the roles of these oxidase machineries, which are anticipated to be critical for the future applications of LAB in industry and comprehending the virulence of pathogenic streptococci.

Potential mechanism of improved cryotolerance of Pediococcus pentosaceus YT2 by cold acclimation based on TMT quantitative proteomics analysis

Lactic acid bacteria (LAB) are used in fermented foods to overcome the shortcomings of traditional fermentation methods, such as long cycles and poor safety. However, the application of LAB in low-temperature foods is limited by their growth temperature. This study aimed to quantitatively compare the proteins of the YT2 strain acclimated at 37, 28, 20, 15, 8, and 4 °C (YT-4) and that grown at 37 °C (YT-37) using tandem mass tag (TMT) proteomics and bioinformatics analysis to elucidate the potential mechanism of cryotolerance of P. pentosaceus YT2. Altogether, 1416 quantitative proteins were identified, of which 747 were differentially abundant between the YT-4 and YT-37 strains. Functional enrichment analysis showed that the upregulated proteins were mainly involved in nucleotide transport, metabolism, translation, ribosomal structure and biogenesis, transcription, replication, recombination, and repair, while the downregulated proteins were involved in lipid, amino, and carbohydrate transport and metabolism. These results were validated for eight upregulated and five downregulated proteins using parallel reaction monitoring (PRM). Our study analyzed the potential mechanism underlying the improved cryotolerance of P. pentosaceus YT2 at 4 °C, which may enable the utilization of LAB in low-temperature applications.

APPLICATION OF BACTERIAL SOURDOUGH AND ENZYMES IN THE PRODUCTION OF BREAD FROM A MIXTURE OF RYE AND WHEAT FLOUR

Interest in sourdough rye-wheat bread with addition of enzymes is actively demonstrated by various manufacturers. Enzymes associated with the metabolic activity of sourdough microorganisms and exogenous enzymes deliberately added to the dough recipe are used in the production of these bakery products. Such combinations contribute to the improvement of both dough structure and the final product. The research investigated the influence of the combined application of the IPROVIT sourdough and enzymes α-amylase, glucoamylase and protease on the structural-mechanical properties of the dough and the quality of the resulting rye-wheat bread. Optimal concentrations of individual enzymes and their combinations were established: α-amylase – 0.35 mL, protease - 0.05 mL, glucoamylase - 3 mL, α-amylase+glucoamylase and α-amylase+protease in a 1:1 ratio. Adding enzymes at rational concentrations positively affected on the physical properties of the dough, making it elastic, shaping well into a ball and preventing spreading. Increased enzyme concentrations led to stickiness and eventual spreading of the dough. It was observed that the combined application of Lactobacillus plantarum, L. brevis, Lactobacillus paracasei ssp. paracasei bacteria and enzymatic preparations (α-amylase, protease, glucoamylase) of different actions positively affected the physical properties of the dough. The dough mixed well, did not stick to hands, maintained its shape, faster increased of volume and had moisture levels within the control range of 41–43%. The acidity of the resulting bread met the requirements of DSTU 4583:2005 and amounted to 8.9–10 degrees for all tested samples. Reduced acidity in the sample with the enzyme complex α-amylase+protease is explained by the fact that the amino acids formed as a result of the protease action were used by lactic acid bacteria as a source of nutrients. The combined application of lactic acid bacteria and enzymes positively contributed to intensifying fermentation processes, indicated by higher dough rising indicators, which were 3–9 min higher than the control. Through the use of enzymes with different actions, it was proven that the organoleptic characteristics of the bread improved, acquiring an attractive color, distinct taste and pleasant specific aroma with hints of nutmeg. The porosity of the experimental bread samples with the enzyme mixture was at the control level. Thus, the use of rye-wheat flour, sourdough and enzymes has a positive effect on the quality of bread and contributes to increasing its nutritional and biological value.

The adsorption of 2-amino-1-methyl-6-phenyl-imidazolium [4, 5-B] pyridine (PhIP) by lactic acid bacteria 37X-15 and its peptidoglycan

The heterocyclic amine 2-amino-1-methyl-6-phenyl-imidazolium [4, 5-B] pyridine (PhIP), commonly found in roasted meat products, is considered a potential carcinogen. This study is to explore the underlying mechanisms involved in the adsorption of PhIP by lactic acid bacteria 37X-15 and its peptidoglycan. The scanning electron microscope results suggested that the strain's adsorption on PhIP occurs on the cell wall, primarily composed of peptidoglycan. The fourier-transformed infrared spectroscopy results indicated that PhIP adsorption by both lactic acid bacteria 37X-15 and its peptidoglycan primarily involved OH and NH binding groups. Different adsorption conditions affected the adsorption rate of PhIP by peptidoglycan. The optimal values for each adsorption condition were 2 h, 37 °C, and pH 6 when the maximum adsorption rate reached. This study provides a new direction for the application of lactic acid bacteria and its peptidoglycan in food safety.

Gut Microbiome Analysis and Screening of Lactic Acid Bacteria with Probiotic Potential in Anhui Swine.

With the widespread promotion of the green feeding concept of "substitution and resistance", there is a pressing need for alternative products in feed and breeding industries. Employing lactic acid bacteria represents one of the most promising antimicrobial strategies to combat infections caused by pathogenic bacteria. As such, we analyzed the intestinal tract of Anhui local pig breeds, including LiuBai Pig, YueHei Pig, and HuoShou Pig, to determine the composition and diversity of intestinal microbiota using 16S rRNA. Further, the functionality of the pigs' intestinal microbiota was studied through metagenomic sequencing. This study revealed that lactic acid bacteria were the primary contributors to the functional composition, as determined through a species functional contribution analysis. More specifically, the functional contribution of lactic acid bacteria in the HuoShou Pig group was higher than that of the LiuBai Pig and YueHei Pig. Subsequently, the intestinal contents of the HuoShou Pig group were selected for the screening of the dominant lactic acid bacteria strains. Out of eight strains of lactic acid bacteria, the acid-production capacity, growth curve, and tolerance to a simulated intestinal environment were assessed. Additional assessments included surface hydrophobicity, the self-aggregation capability, co-agglutination of lactic acid bacteria with pathogenic bacteria, and an in vitro bacteriostatic activity assay. Lactobacillus johnsonii L5 and Lactobacillus reuteri L8 were identified as having a strong overall performance. These findings serve as a theoretical basis for the further development of pig-derived probiotics, thereby promoting the application of lactic acid bacteria to livestock production.

Effect of lactic acid bacteria and Bacillus on anthracnose disease in postharvest papaya fruit

Abstract. Thi QVC, Dung TQ, Huynh NTN, Truc NT, Thuy NP. 2023. Effect of lactic acid bacteria and Bacillus on anthracnose disease in postharvest papaya fruit. Biodiversitas 24: 5883-5894. Anthracnose disease of papaya fruit caused by Colletotrichum (isolate TD1), identified by 5.8S rRNA sequence homology, is a main obstacle in papaya fruit, influencing fruit quality and minimizing shelf life. Therefore, to diminish the disease and sustain the fruit quality, the impact of Lactic Acid Bacteria (LAB) and Bacillus on the growth of anthracnose disease and fruit quality was investigated in vitro and in vivo. Furthermore, 13 LAB and 12 Bacillus isolates were collected from traditional fermented vegetables and papaya rhizospheric soils. The results showed that 13 LAB isolates and 6 isolates of Bacillus were inhibitory against Colletotrichum in an in vitro test. Two isolates of LDC11 and BHL21 with the highest antifungal activity were selected to evaluate their effect on Colletotrichum growth and papaya fruit quality under in vivo conditions. These findings indicated that the isolates LDC11 and BHL21 at a density of 106 CFU/mL reduced the disease incidence and severity. The LAB and Bacillus treated papaya fruit increased a number of parameters, such as weight loss, TSS, and L*, a*, and b* values. However, vitamin C content, TA, and fruit firmness were reduced compared to the control. The research shows a potential applications of LAB and Bacillus in the postharvest preservation of papaya fruit. To our knowledge, this is the first study to apply Bacillus and LAB bacteria to control diseases in postharvest papaya in Vietnam.

Probiotic potential and safety analysis of lactic acid bacteria isolated from Ethiopian traditional fermented foods and beverages

BackgroundProbiotics are live microorganisms that effectively combat foodborne pathogens, promoting intestinal health when consumed in sufficient amounts. This study evaluated the probiotic potential and safety of lactic acid bacteria isolated from selected Ethiopian traditional fermented foods and beverages (Kotcho, Bulla, Ergo, Cabbage-Shamita, Borde, and Bukuri). To assess the isolates’ probiotic activity, tolerance, and survival rate under various stressful conditions, including low pH, intestinal inhibitory substances, salt concentration, bile salt, and simulated gastric/intestinal juice. The isolates were also tested for antagonistic activities against common bacterial and fungal pathogens (Staphylococcus aureus, Salmonella Typhimurium, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans) and safety (auto-aggregation, co-aggregation, cell source hydrophobicity, hemolytic activity, DNase, and antibiotic susceptibility). The best probiotic lactic acid bacteria (LAB) were characterized to species level following standard MALDI TOF/mass spectrometry analysis.ResultsA total of 125 potentially probiotic LAB were isolated of which 17 (13.60%) isolates survived low pH (2, 2.5, and 3), bile salt (0.3%), intestinal inhibitory chemicals (phenol, bile, low acidity, pepsin, and pancreas), and simulated gastro-intestinal settings with near 60–94% survival rate. In addition, 11 best LAB isolates were further screened based on additional screening including their antimicrobial efficacy, preservative efficiency, bacteriocin production besides resistance to low acid and bile salts, and survival potential under simulated gastrointestinal conditions. All 11 LAB isolates were resistant to ampicillin, vancomycin, gentamicin, kanamycin, clindamycin, and chloramphenicol, while they were susceptible to streptomycin and tetracycline. The MALDI TOF mass spectrometry analysis result of efficient probiotic LAB grouped them under the genus Pediococcus, Enterococcus, and Lactococcus including Pediococcus pentosaceus, Enterococcus faecium, Lactococcus lactis, and Pediococcus acidilactici.ConclusionEthiopian traditional fermented foods and beverages are good sources of promising probiotic lactic acid bacteria. These isolates could serve as potential starter cultures and bio-preservative for the enhancement of the shelf life of foods. This study established the groundwork for the selection of excellent probiotics for the development and application of LAB for antibacterial action, starter culture production, and preservation activities.

Protection Mechanism of Metal Ion Pre-Stress on Lactobacillus acidophilus CICC 6074 under Acid Tolerance.

The prerequisite for the probiotic effect of lactic acid bacteria is that they could survive the acid stress environment of production and application. In this experiment, the mechanism for the effect of different metal ion pre-stress on the acid-tolerant survival of Lactobacillus was investigated. Scanning electron microscopy, Fourier infrared spectroscopy, and flow cytometry were used to analyze the condition of bacteria after acid treatment, which revealed that different metal ion pre-stress could improve the survival ability of Lactobacillus acidophilus CICC 6074 under low acid conditions by improving cell morphology, mitigating cell membrane damage, and regulating surface protein expression. Furthermore, Tandem Mass Tags (TMT) proteomic analysis revealed that Mn2+ pre-stress showed relatively more superior protective effects on acid tolerance in L. acidophilus CICC 6074 through activation of DNA replication, RNA synthesis, S-layer protein secretion, H+-ATPase enzyme activity, etc. This study will provide new ideas and a theoretical basis for the development and application of lactic acid bacteria.