Lactic Acid Bacteria Strains Research Articles

Comparative microbiological, chemical, and sensory traits of aron fermentation in Tengger and laboratory scales

Aron, a traditional fermented food of the Tengger community, is made from white corn grown in Bromo and has received limited microbiological, chemical, and sensory research attention to date. The research objective was to compare microbiological, chemical, and sensory traits between in situ-produced aron on the slopes of Mount Bromo and ex situ-produced aron in a laboratory in Surabaya. A specific strain of lactic acid bacteria was isolated using de Man, Rogosa, and Sharpe (MRS) Agar from samples of sun-dried white corn. This strain was identified as Gram-positive cocci. In contrast, a different strain of Gram-positive bacilli was found in corn-soaking water, both in situ and in laboratory-fermented aron, on days 0, 7, and 16. Chemical analysis revealed no significant differences in protein, fat, and ash content between the two variables. However, laboratory-fermented aron exhibited higher moisture content. This discrepancy significantly influenced the hedonic texture data for aron, with in situ aron being perceived as drier and more mouth-soluble, while laboratory-fermented aron had a softer texture. Furthermore, the high microbial growth during the fermentation process resulted in aron with a distinct and relatively strong aroma that was less favored by the panelists. The difference in the fermentation location of white corn did not affect the types of lactic acid bacteria that thrived, the nutritional compound content, and the appearance of aron. The variation in the aroma of aron is believed to be primarily influenced by the number of bacteria rather than their specific strains.

Effects of Probiotic Supplementation on Body Weight, Growth Performance, Immune Function, Intestinal Microbiota and Metabolites in Fallow Deer.

Intestinal diseases are one of the diseases that affect the growth and immunity of deer. Currently, more lactic acid bacteria (LAB) are available as feed additives to improve the intestinal ecological balance of ruminants in production practices. In this study, Enterococcus faecalis was supplemented in the feed of fallow deer for 170 d, and body weights, blood indices and immune levels of fallow deer were counted at 35, 65 and 170 d. The effects of Enterococcus faecalis on the intestinal microbiota and the metabolism of fallow deer were analysed using 16S rDNA and UPLC-MS/MS methods. The results showed that the addition of Enterococcus faecalis to the diet improved body weight and immune function and increased the aggregation of gut microbiota in fallow deer. The addition of Enterococcus faecalis altered the community structure of intestinal microorganisms in fallow deer and increased the number of beneficial bacteria. In addition, combined with metabolomics analysis, it was found that supplementation with Enterococcus faecalis significantly altered the metabolites of fallow deer, mainly regulating lipid metabolism, carbohydrate metabolism and phospholipid metabolism. In conclusion, this study presents, for the first time, evidence that the LAB strain Enterococcus faecalis can be used as a potential probiotic for deer and points to a new direction for the treatment of intestinal disorders in the deer family.

Multi-functional properties of lactic acid bacteria strains derived from canine feces.

Probiotics, especially Lactic Acid Bacteria (LAB), can promote the health of host animals in a variety of ways, such as regulating intestinal flora and stimulating the host's immune system. In this study, 206 LAB strains were isolated from 48 canine fecal samples. Eleven LAB strains were selected based on growth performance, acid and bile salt resistance. The 11 candidates underwent comprehensive evaluation for probiotic properties, including antipathogenic activity, adhesion, safety, antioxidant capacity, and metabolites. The results of the antipathogenic activity tests showed that 11 LAB strains exhibited strong inhibitory effect and co-aggregation ability against four target pathogens (E. coli, Staphylococcus aureus, Salmonella braenderup, and Pseudomonas aeruginosa). The results of the adhesion test showed that the 11 LAB strains had high cell surface hydrophobicity, self-aggregation ability, biofilm-forming ability and adhesion ability to the Caco-2 cells. Among them, Lactobacillus acidophilus (L177) showed strong activity in various adhesion experiments. Safety tests showed that 11 LAB strains are sensitive to most antibiotics, with L102, L171, and L177 having the highest sensitivity rate at 85.71%, and no hemolysis occurred in all strains. Antioxidant test results showed that all strains showed good H2O2 tolerance, high scavenging capacity for 1, 1-diphenyl-2-trinitrophenylhydrazine (DPPH) and hydroxyl (OH-). In addition, 11 LAB strains can produce high levels of metabolites including exopolysaccharide (EPS), γ-aminobutyric acid (GABA), and bile salt hydrolase (BSH). This study provides a thorough characterization of canine-derived LAB strains, highlighting their multifunctional potential as probiotics. The diverse capabilities of the strains make them promising candidates for canine dietary supplements, offering a holistic approach to canine health. Further research should validate their efficacy in vivo to ensure their practical application.

Mixed culture fermentation using Lactobacillus delbrueckii and novel Lactiplantibacillus plantarum strains isolated from traditional chhurpi from Sikkim Himalayan region for potential probiotic and improved functional properties

The aim of the study was to isolate potential probiotic lactic acid bacteria (LAB) strains from the traditional fermented milk products, Chhurpi of the Sikkim Himalayan region and to prepare curd using mixed culture fermentation. A preliminary probiotic assessment of 110 LAB isolates including antimicrobial activity, bile and acid tolerance, surface hydrophobicity, auto-aggregation and co-aggregation, and adhesion to Caco-2 cells, was performed. Lactiplantibacillus plantarum strains N4, CHDE2, CHDE4, and SS22 demonstrated better viability in bile (0.3%) and acid (pH 2.5), adherence with hydrophobicity (13.93–92.85%), auto-aggregation (72.44–89.74%), adhesion to Caco-2 cells (45–73.61%) and antimicrobial activity against food borne pathogens. These strains were used for mixed culture fermentation with a previously screened curd forming strain Lactobacillus delbrueckii WS4. Curd produced using mixed culture fermentation of Lb. delbrueckii WS4 and the selected Lp. plantarum strains had a relatively higher acid production (pH 3.97–4.01), protein hydrolysis, and antioxidant activity. Further, mixed culture fermentation also resulted in the increase of HOCl scavenging activity (12.22–32.96%), myeloperoxidase (MPO) inhibition activity (22.38–42.94%) and angiotensin converting enzyme (ACE) inhibition (15.61–33.03%) as compared to that of WS4 fermentation (P < 0.05). This is the first report on identification of potential probiotic strains from the traditional fermented milk products of Sikkim and application in mixed culture fermentation with enhanced multifunctional potential.

Screening of the Lipid-Lowering Probiotic Lactiplantibacillus Plantarum SDJ09 and its Anti-Obesity Mechanism.

In this study, 39 strains of lactic acid bacteria were screened from several fermented foods. Based on the evaluation of functional and prebiotic properties, Lactiplantibacillus plantarum SDJ09 was selected as a promising candidate. It gave a 48.16% cholesterol reduction and 33.73% pancreatic lipase inhibition in cells; exhibited high resistance to acid, bile salts, and gastrointestinal fluid; and had strong antibacterial activity and high adhesion capabilities. More importantly, the lipid-lowering effect of L. plantarum SDJ09 was also investigated using 3T3-L1 mature adipocytes and HepG2 nonalcoholic fatty liver disease models. L. plantarum SDJ09 effectively decreased triglyceride accumulation by more than 50% in both cell models, in which the expression of PPARγ, C/EBPα, aP2, and LPL in 3T3-L1 cells was significantly downregulated by L. plantarum SDJ09. L. plantarum SDJ09 also improved lipid metabolism by downregulating the expression of HMGCR, SREBP-1c, ACC, and FAS and upregulating the expression of CYP7A1 in HepG2 nonalcoholic steatohepatitis cells. Therefore, L. plantarum SDJ09 has the potential to effectively decrease obesity and non-alcoholic fatty liver disease (NAFLD) by inhibiting lipid accumulation, providing a prospective probiotic agent for anti-obesity.

Contributions of Gamma-Aminobutyric Acid (GABA) Produced by Lactic Acid Bacteria on Food Quality and Human Health: Current Applications and Future Prospects.

The need to increase food safety and improve human health has led to a worldwide increase in interest in gamma-aminobutyric acid (GABA), produced by lactic acid bacteria (LABs). GABA, produced from glutamic acid in a reaction catalyzed by glutamate decarboxylase (GAD), is a four-carbon, non-protein amino acid that is increasingly used in the food industry to improve the safety/quality of foods. In addition to the possible positive effects of GABA, called a postbiotic, on neuroprotection, improving sleep quality, alleviating depression and relieving pain, the various health benefits of GABA-enriched foods such as antidiabetic, antihypertension, and anti-inflammatory effects are also being investigated. For all these reasons, it is not surprising that efforts to identify LAB strains with a high GABA productivity and to increase GABA production from LABs through genetic engineering to increase GABA yield are accelerating. However, GABA's contributions to food safety/quality and human health have not yet been fully discussed in the literature. Therefore, this current review highlights the synthesis and food applications of GABA produced from LABs, discusses its health benefits such as, for example, alleviating drug withdrawal syndromes and regulating obesity and overeating. Still, other potential food and drug interactions (among others) remain unanswered questions to be elucidated in the future. Hence, this review paves the way toward further studies.

The impact of lactic acid bacteria inoculation on the fermentation and metabolomic dynamics of indigenous Beijing douzhi microbial communities.

Douzhi, a traditional Chinese fermented beverage, features microbial communities primarily composed of lactic acid bacteria (LAB). As fermented foods continue to gain recognition and popularity, douzhi is attracting growing interest. However, investigation of the critical aspects of douzhi's fermentation processes, including fermentation characteristics and microbial community dynamics, remains vital for enhancing food safety and quality for douzhi, as well as for similar fermented food products. In this study, we collected douzhi microbial communities from four chain stores, using them as fermentation starter cultures. The microbial dynamics of the fermentation were analyzed, focusing on the inoculation of LAB strains and the transition from a mung bean-based matrix to skimmed milk. The metabolomic profiles of the fermented mung bean matrices were also studied. Douzhi samples obtained from representative chain stores were found to be overwhelmingly dominated by LAB. When inoculated along with the douzhi community, both LAB strains exhibited notable and substantial reductions in the pH value of the designated mung bean matrices compared to those inoculated indigenous microbiota. Specifically, Lactiplantibacillus plantarum CGMCC 1.1856 retained its population, whereas Pediococcus pentosaceus CGMCC 1.2695 exhibited a decrease in relative abundance. Using skimmed milk as a fermentation substrate instead of the mung bean matrix resulted in significant shifts in microbial communities, particularly leading to an increase in Escherichia sp. The metagenomic analyses and functional predictions illustrated that various metabolic functions were enhanced during the fermentation process due to LAB inoculation. The liquid chromatography-mass spectrometry based metabolomic analysis revealed that the inoculation of Lactiplantibacillus plantarum and Pediococcus pentosaceus in mung bean matrix did not introduce new metabolites but significantly altered the concentration and profile of existing metabolites, especially increased low molecular carbohydrates, which may enhance the nutritional potential of the fermented product. This study examines the microbial dynamics of douzhi microbiota fermentation, emphasizing the role of lactic acid bacteria in enhancing fermentation activity and metabolite profiles. These insights contribute to improving manufacturing processes and ensuring the safety and quality of douzhi and similar fermented foods.

In vitro assessment of probiotic properties of lactic acid bacteria isolated from camel milk: enhancing sustainable foods

Probiotic properties of isolated lactic acid bacteria (LAB) from sustainable foods including camel milk are the potential research domains. For this purpose, camel milk samples (n = 20), from four different herds of Camelus dromedarius, were processed for the identification of LAB strains based on biochemical profiles followed by amplification and sequence analysis of the 16S rRNA gene. The probiotic characteristics, i.e., acids and bile salts tolerance, antimicrobial susceptibility profiles, hemolytic and antimicrobial activities, auto-aggregation assay, and adhesion to HT-29 epithelial cells were determined. Thirteen out of 20 milk samples were initially found positive for the growth of probiotics or LAB which were further confirmed as Lacticaseibacillus casei (5) and Pediococcus pentosaceus (3). The probiotics/LAB strains showed maximum survival (%) = 92.06 ± 1.82 and 81.35 ± 3.64 against acids and bile salts, respectively. The LAB strains were found sensitive to amoxicillin, ceftazidime, imipenem, linezolid, ofloxacin, tetracycline, tobramycin, and vancomycin. None of the LAB strains showed hemolytic activity. L. casei-04 strain showed a maximum zone of inhibition (15.33 ± 0.58) against multidrug-resistant E. coli AZ1 strain whereas, L. casei-05 showed a maximum zone of inhibition (16.33 ± 1.15) against methicillin-resistant S. aureus Saba-1 strain. L. casei-03 showed maximum percentage auto-aggregation (28.65 ± 1.96) at 4 h while L. casei-01 showed (41.10 ± 3.03) at 24 h of incubation. Maximum adhesion was shown by P. pentosaceus-01 (11.14%) followed by L. casei-02 (9.73%). Altogether, the current findings suggested that camel milk has significant potential of providing probiotics/LAB strains into human food chain and enabling camel milk as potential sustainable food.

In vitro probiotic potential of lactic acid bacteria isolated from the intestines of Muscovy ducks.

The current study was conducted to isolate, test and characterize molecularly and physiologically lactic acid bacteria from the intestines of Muscovy ducks to evaluate their probiotic potential for poultry farming. Three hundred lactic acid bacteria from the gastrointestinal tract of Muscovy ducks were isolated. The strains were phenotypically characterized by observing cell morphology, performing Gram staining, catalase production, and testing their ability to grow in MRS broth at different temperatures, pH values, NaCl concentrations, bile concentration, and in compatibility tests between strains. Nine strains were selected based on their resilience. Eight strains were identified using molecular techniques. These strains exhibited significant tolerance to acidic pH, bile salts, and NaCl, essential for probiotic function. All isolates inhibited the growth of Salmonella enterica serotype Typhimurium (DT104) and Enteropathogenic Escherichia coli serotype O86:H34 (EPEC), showcasing their antimicrobial potential. Antibiotic susceptibility testing revealed 100% resistance to clindamycin and erythromycin but high susceptibility to ampicillin and vancomycin. Growth was observed at various temperatures, indicating mesophilic characteristics. Compatibility tests confirmed their suitability for probiotic formulations. Genomic analysis identified the strains primarily as Enterococcus. Conclusively, the study identified eight out of nine selected lactic acid bacteria strains from Muscovy ducks as autochthonous probiotics, showing resilience to treatments and compatibility for consortium formulation. These strains are suitable for in vivo testing for potential poultry farming applications. Further research on their molecular mechanisms and in vivo effects is needed.

Characterization of nuvita biosearch center (NBC) isolated lactic acid bacteria strains from human origin and determination of growth kinetic profiles of selected cultures under bioreactor

BackgorundIn recent years, there has been an increasing interest in the field of research into the isolation and characterization of probiotics in the prevention of diseases and the need to maintain the continuity of healthy microbiota. Therefore, the aim of this study is to isolate and identify bacteria found in maternal colostrum, breast milk, adult and infant feces, analyze possible probiotic potential, and reveal the developmental kinetics of selected strains.ResultsWe isolated 40 bacterial species from 4 different sources and identified 19 bacteria in the form of bacilli through molecular biology and carried out studies with 11 of them. Five of the selected strains showed the better results considering bile salt resistance and ability to survive at different pH and antimicrobial effect. When the adhesion capacity in cell culture is examined, the better 2 strains are; Lactobacillus pontis ZZ6780 and Lactobacillus reuteri NBC2680 were selected and the growth kinetics of these strains were demonstrated at the 3 L bioreactor scale. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected Lactobacillus pontis ZZ6780 and Lactobacillus reuteri NBC2680 was calculated as 0.412 h− 1 and 0.481 h− 1, respectively. In addition, the dry cell matter amounts were found to be and 4.45 g/L and 5.23 g/L, respectively.ConclusionThis study established the groundwork for the selection of safety probiotics for the development and application of LAB. It is thought that the two strains obtained as a result of this study can be considered as potential probiotic strains in the food, pharmaceutical and cosmetic industries.

Fermentation of Rice, Oat, and Wheat Flour by Pure Cultures of Common Starter Lactic Acid Bacteria: Growth Dynamics, Sensory Evaluation, and Functional Properties.

Recent consumer demand for non-dairy alternatives has forced many manufacturers to turn their attention to cereal-based non-alcoholic fermented products. In contrast to fermented dairy products, there is no defined and standardized starter culture for manufacturing cereal-based products. Since spontaneous fermentation is rarely suitable for large-scale commercial production, it is not surprising that manufacturers have started to adopt centuries-known dairy starters based on lactic acid bacteria (LABs) for the fermentation of cereals. However, little is known about the fermentation processes of cereals with these starters. In this study, we combined various analytical tools in order to understand how the most common starter cultures of LABs affect the most common types of cereals during fermentation. Specifically, 3% suspensions of rice, oat, and wheat flour were fermented by the pure cultures of 16 LAB strains belonging to five LAB species-Lacticaseibacillus paracasei, Lactobacillus delbrueckii, Lactobacillus helveticus, Streptococcus thermophilus, and Lactococcus lactis. The fermentation process was described in terms of culture growth and changes in the pH, reducing sugars, starch, free proteins, and free phenolic compounds. The organoleptic and rheological features of the obtained fermented products were characterized, and their functional properties, such as their antioxidant capacity and angiotensin-converting enzyme inhibitory activity, were determined.

Fermented Ananas comosus and Carica papaya harbour putative probiotic Limosilactobacillus fermentum and Lacticaseibacillus paracasei strains with inhibitory activity against α-glucosidase and α-amylase

Diabetes mellitus (DM) is the condition represented by persistent hyperglycaemia, owing to the altered glucose metabolism. The current research aims to assess the capabilities of strains of lactic acid bacteria (LAB) that were obtained from fermented Ananas comosus (A. comosus) and Carica papaya (C. papaya) (non-dairy sources) as probiotics for the prevention of DM. The capacity of the strains to endure or survive extreme conditions was evaluated using bile tolerance using oxgall at varying concentrations, hydrophobicity, coaggregation ability, adhesion ability, and hemolytic activity, and their survival rate in gastric and intestinal juices. The LAB strains demonstrated the following results: phenol (>7 Log CFU/mL), acid-bile conditions (6.53–7.11 Log CFU/mL), gastric and intestinal juice tolerance (6.18–7.33 Log CFU/mL), thereby fulfilling the requirements to be a prospective probiotic agent. The LAB strains showed characteristics of cell surface hydrophobicity (≥ 40 %), autoaggregation (≥ 70 %), and coaggregation (≤ 48 %). Furthermore, they demonstrated antioxidant activity (≥ 59 %) as well as the ability to lower blood sugar levels by inhibiting α-glucosidase (≤ 57 %) and α-amylase (≤ 64 %). The development of antidiabetic probiotics from fermented papaya and pineapple has several potential uses. These probiotics may be used as functional foods or supplements to improve glycemic control in individuals with DM. They may also be used as adjunct therapies to conventional diabetes treatments to enhance their efficacy. The results of this research may pave way for creating probiotic products that function as food additives or supplements, with the aim of enhancing health and preventing long-term illnesses like diabetes. Additionally, probiotics have been proven to boost intestinal health, regulate the immune system, and decrease inflammation.

Isolation and characterization of probiotic lactic acid bacteria from local yogurt and development of inulin-based synbiotic yogurt with the isolated bacteria

Synbiotic yogurts can offer several potential benefits due to the combination of yogurts probiotics, prebiotics, and the nutritional qualities of milk. Local yogurt variants might add to the variety of probiotic alternatives because they frequently have distinct microbial communities. Employing indigenous strains not only represents cultural preferences but also increases the probability of obtaining bacteria adapted to the surrounding environment. This study was intended to isolate and characterize potential lactic acid bacterial strains from local yogurt and assess the effectiveness of inulin on the physicochemical and microbiological properties during the fermentation of synbiotic yogurt. A total of eight strains were identified and isolated. Two chosen isolates were combined with inulin at 0, 0.5, 1, and 1.5 % concentrations to produce synbiotic yogurts. The physicochemical and microbiological properties were assessed during the fermentation process of synbiotic yogurts. The result showed that the isolated Lactobacillus spp. and Streptococcus spp. strains had probiotic characteristics and good growth. After the fermentation, the yogurt sample containing 1.5 % inulin had the highest count of Lactobacillus spp. (8.17 ± 0.01 log CFU/ml) and Streptococcus spp. (8.03 ± 0.03 log CFU/ml), highest optical density (2.931 ± 0.001), acidity (1.43 ± 0.03), and water-holding capacity (63.54 ± 0.51), and lowest syneresis (34.75 ± 0.48). The addition of inulin did not affect color during the fermentation of synbiotic yogurt. This study concluded that inulin could boost yogurt's stability when combined with local lactic acid bacteria strains.

Molecular characterization and multifunctional evaluation of lactic acid bacteria isolated from traditional sourdough

The primary objective of this study was to characterize lactic acid bacteria (LAB) strains derived from sourdough for possible utilization as functional starters to produce sourdough and various cereal-based fermented foods. A total of 350 autochthonous LAB strains were isolated from 65 Type I sourdough samples and characterized using six random amplified polymorphic DNA (RAPD) primers at intra- and interspecific levels. Species identification of selected strains representing distinct clusters from RAPD analysis was performed based on the 16S rRNA region. The LAB strains were identified as Companilactobacillus crustorum (n = 135), Levilactobacillus brevis (n = 125), Latilactobacillus curvatus (n = 40), Companilactobacillus paralimentarius (n = 32), and Lactiplantibacillus plantarum (n = 18). A total of 66 LAB strains were selected for technological characterization along with two commercial strains. The characterization involved acidity development, EPS production potential, leavening activity, and growth abilities under harsh conditions. Principle component analysis (PCA) identified 2 Lp. plantarum and 14 Lev. brevis strains as the most relevant technologically. Among them, Lp. plantarum L35.1 and Lev. brevis L37.1 were resistant to tetracycline. Evaluation of probiotic characteristics (survival in pH 2.5 and bile presence, auto aggregation capacity, hydrophobic activity, antioxidant activity, antimicrobial activity) by PCA identified four strains with relevance to Lactobacillus rhamnosus GG (LGG), which were further selected for in vitro digestion assays. Lactiplantibacillus plantarum L7.8, Lev. brevis L55.1, and L62.2 demonstrated similar viability indices to LGG, along with increased auto aggregation capacity and antioxidant activity. These strains are promising as candidate starters for producing sourdough and sourdough-related fermented food products.

Investigation of some probiotic and technological properties of lactic acid bacteria strains isolated from artisanal sheep milk cheese and their growth in goat milk

The objective of this study was to assess the probiotic and technological properties of lactic acid bacteria (LAB) isolated from artisanal sheep milk cheeses for potential use in dairy products made from goat milk. Strains studied were Lacticaseibacillus paracasei LC6, Lactiplantibacillus plantarum LP48, Lactococcus lactis subsp. hordniae LH69 and Leuconostoc mesenteroides LM99. The criteria studied were fermentative capacity, carbohydrate fermentation profile, β-galactosidase (lactase) activity, auto-aggregation capacity, hydrophobicity, antimicrobial activity, resistance to simulated gastric secretion, bile resistance, and resistance to different pH and salts concentrations, as well as growth and viability in goat milk. In general, the strains studied showed characteristics compatible with potential probiotic effects. However, according to criteria studied, L. plantarum LP498 best met the conditions; it was compatible with probiotic potential under all the conditions considered and showed noteworthy differences compared to the other micro-organisms studied, particularly in its capacity for self-aggregation and pH resistance. Therefore, L. plantarum LP48 could be adequate for the manufacture of artisanal goat milk products.

Inhibition of Botrytis cinerea and Escherichia coli by Lactic Acid Bacteria on Leafy Vegetables

The evaluation of the potentiality of lactic acid bacteria (LAB) strains isolated from fermented products to inhibit Botrytis cinerea and Escherichia coli O157:H7 growth on spinach and lettuce was conducted. From a total of forty LAB strains tested, three were selected due to their high inhibitory effect on plant pathogenic fungi. The identification of these isolates based on a 16S rRNA gene fragment sequence analysis confirmed the genus of Levilactobacillus sp. and Lactiplantibacillus sp. An effective method of coating LAB isolates on the lettuce and spinach surface was developed. The leaves were immersed in bacterial suspension (5.0 × 106 cfu mL−1) for 4 s and drained on tissue paper. LAB survived on lettuce and spinach leaves for 8 days at 6 log10 cfu g−1. Additionally, these bacteria decreased the number of filamentous fungi on the leaves. These isolates were found to inhibit the growth of B. cinerea and E. coli O157:H7 in vitro conditions in growing microbiological media. Their efficacy was confirmed in vivo conditions. These isolates inhibited the development of grey mould caused by B. cinerea on lettuce leaves. Two LAB isolates reduced the abundance of the pathogenic bacterium E. coli on spinach leaves by about 0.7 log10 cfu g−1. In glasshouse conditions, LAB stimulated the growth of examined plants. The lactic acid bacteria used in this study showed the capacity to be used as possible alternatives to chemical compounds in the protection of leafy vegetables against grey mould and for a decrease in E. coli O157:H7 contamination.

Probiotic Potential of Lactobacillus and Enterococcus Strains Isolated From the Faecal Microbiota of Critically Endangered Hangul Deer (Cervus hanglu hanglu): Implications for Conservation Management.

The mammalian gut microbiota plays a crucial role in promoting host health, and lactic acid bacteria (LAB) are commonly employed as probiotics for their beneficial effects. The Hangul deer (Cervus hanglu hanglu), a critically endangered red deer subspecies found in the Indian subcontinent, requires meticulous health management for its conservation. This pioneering study aimed to isolate, identify, and evaluate the in-vitro probiotic functional properties of LAB strains from the faeces of Hangul deer. A total of 27 LAB strains were isolated and identified using 16S rDNA gene sequencing, followed by comprehensive probiotic characterization and safety assessment. Remarkably, four species exhibited robust resistance and survivability against varying pH levels and bile salts, along with high aggregation and co-aggregation capacities. Notably, Lactobacillus acidophilus and Enterococcus mundtii strains displayed antibacterial activities. Safety assessment revealed the absence of hemolytic activity and virulence genes in all four strains. Antibiotic susceptibility testing showed that Lactobacillus acidophilus and Enterococcus casseliflavus were susceptible to all tested antibiotics, while Enterococcus mundtii exhibited resistance to clindamycin, and Enterococcus gallinarum exhibited resistance to erythromycin. These findings suggest that the isolated LAB strains possess advantageous probiotic characteristics and hold potential as dietary supplements for promoting the health and disease management of Hangul deer.

Screening of lactic acid bacteria with the ability to reduce goaty flavor related fatty acids in goat milk

In this study, we conducted sensory evaluation and gas chromatography–mass spectrometry analysis on fermented goat milk samples prepared by 12 strains of lactic acid bacteria (LAB) isolated from goat milk to screen for strains with the ability to reduce the goaty flavor. The bacterial counts of fermented goat milk was 7.07–9.01 log CFU/mL. The electronic nose distinguished fresh goat milk (FGM) and fermented goat milk, and the electronic tongue results showed that Leuconostoc citreum 1, 4, 20, 22, 32, and 57, Latilactobacillus curvatus 144 and 147 imparted fermented goat milk a taste different from FGM. Overall, Leuconostoc citreum 57, Leuconostoc citreum 126, Latilactobacillus curvatus 142, Latilactobacillus curvatus 143, and Latilactobacillus curvatus 147 were screened with the ability to improve the flavor of goat milk. They gave fermented goat milk a goat flavor score lower than or equal to FGM. And the fermented goat milk samples 57, 126, 142, 143, and 147 contained 25, 22, 15, 24, and 17 volatile flavor compounds, respectively, with a greater variety and content of ketones and aldehydes and lower levels of hexanoic acid, octanoic acid, and decanoic acid than FGM. However, the pH and WHC results indicated that the application of these strains as secondary cultures is necessary. Our finding provides basic research data to improve the flavor of goat milk products.

Lactic acid bacteria with weak post-acidification potential applied for low-salt paocai fermentation: A perspective from screening to molecular mechanism

Reducing post-acidification is crucial for extending the shelf-life and facilitating industrial-scale production of low-salt paocai. This study aimed to screen and identify a lactic acid bacteria strain with weak post-acidification potential from 39 commonly used strains in vegetable fermentation. We employed transcriptomic and metabolite analysis to investigate the mechanisms underlying the weak post-acidification traits of the selected strain. Notably, W. cibaria SC5R3 had a minimum survival rate at pH 4.5 by 39.02% and survival rate to pH 4.0 was only 1.82%. The incorporation of W. cibaria SC5R3 in low-salt paocai showed a low content of total titratable acidity and stable viable count during 8 days of storage at 25 °C, which also exhibited good sensory quality. Furthermore, W. cibaria SC5R3 exhibited significant down-regulation of genes associated with the hetero-fermentation pathway during late-stage fermentation, contributing to its weak acid-producing characteristic. The strain SC5R3 displayed deficiencies in the glutamate decarboxylase system, histidine synthesis, and aspartate metabolism, along with reduced H⁺-ATPase activity in acidic environments, making it sensitive to acid. This research provides valuable insights into optimizing low-salt paocai fermentation processes and improving product quality by minimizing acidity changes during shelf-life storage.

Screening and characterization of lactic acid bacteria with antibacterial effect against heat-resistant spore outgrowth of Bacillus sporothermodurans

This study is the first to screen of lactic acid bacteria strains with antimicrobial effect against spore outgrowth of Bacillus sporothermodurans and characterize their technological properties. Eighty strains were isolated from Tunisia raw milk but only 8 isolates were selected based on their antagonistic activity against germinated spores of B. sporothermodurans and nine pathogenic bacteria. Phenotypic and genotypic characterization allowed us to distinguish three different species, namely Lactiplantibacillus plantarum, Levilactobacillus brevis and Lactococcus lactis. The lactic acid strains able to produce protease and lipase enzymes. The important antagonistic activity was observed in presence of L. lactis TLAB6 strain which produced a bacteriocin and lactic acid. The bacteriocin produced by the L. lactis TLAB6 is heat stable and resistant to trypsin. The results suggest that the selected LAB with antibacterial activity against germinated spore and technological properties may be used to preserve the food and formulate of bioactive functional foods.