Lactic Acid Bacteria Isolates Research Articles

Assessment of the nutritional quality of weaning food prepared from fermented blends of sorghum (Ogi) and soybean

This study investigated the nutritional quality of weaning food prepared from fermented blends of sorghum (ogi) and soybean. The raw samples were processed into flour and were mixed in ratio of 60:40 and 70:30 respectively. Lactic acid bacteria (LAB) were isolated from fermented ogi and were accessed for their technological properties. The pH and total titratable acidity of the ogi was accessed, proximate composition and shelf-life of the weaning blends were determined by standard methods. A total of 10 LAB isolates were obtained, characterized and identified as L. plantarum (50%), L. fermentum (30%), L. delbrueckii (10%), and L. brevi (10%). Lactic acid, diacetyl and hydrogen peroxide produced by the LAB isolates ranged from 1.203 ± 0.006 - 3.410 ± 0.010, 1.21 ± 0.02 - 3.63 ± 0.05 and 0.650 ± 0.060 - 1.910 ± 0.040 (mg/mL) respectively. The fermentation of the ogi resulted in pH reduction from 4.5 ± 0.01- 2.40 ± 0.01 and increased titratable acidity 12.49 ± 0.01 - 23.00±0.01 g/L. The 60:40 weaning blend of sorghum ogi flour and soybean improved protein, ash, crude fiber, moisture, fat, vitamin A, ascorbic acid, riboflavin, and beta carotene content compared to a 70:30 blend. The blend also showed improvements in mineral content, with a significantly higher overall nutritional value compared to the 70:30 blend. Coliforms were not observed during the shelf-life monitoring. This study concluded that these blends meet daily nutritional requirements, provide health benefits, and meet recommended standards for weaning.

In Vitro Probiotic Characterization of Lactiplantibacillus plantarum Strains Isolated from Traditional Fermented Dockounou Paste

This study aimed to evaluate the probiotic properties of 10 lactic acid bacteria (LAB) isolated from artisanal fermented plantain dockounou paste. A preliminary characterization of the LAB isolates was performed based on phenotypic and several biochemical properties, which was subsequently confirmed through 16S rRNA gene sequencing analysis, indicating that these isolates belonged to the species Lactiplantibacillus plantarum. With regard to safety criteria, the strains exhibited no alpha or beta hemolysis activity. Nevertheless, the majority of LAB strains demonstrated high sensitivity to the antibiotics tested. The results demonstrated that the majority of the strains exhibited remarkably high survival rates under simulated gastrointestinal conditions, such as pH = 1.5 (81.18–98.15%), 0.3% bile salts (68.62–100.89%), 0.4% phenol (40.59–128.24%), as well as 0.1% pepsin and pH = 2.5 (88.54–99.78%). The LAB strains demonstrated elevated levels of cell surface properties, indicative of the presence of a considerable defensive mechanism against pathogens. Intact LAB cells exhibited significant antioxidant abilities (48.18–83.58%). They also demonstrated a pronounced inhibitory effect on the growth of foodborne pathogens. Enzyme pattern analysis revealed that the LAB isolates produced both proteases and cellulases, as well as pectinase and/or amylase activity. The potential of the L. plantarum strains FS43, FS44, and FS48, as indicated by the results obtained from the standard in vitro assays, makes them suitable for further study as potential probiotics.

Standardization on Fermentation of Chia (Salvia hispanica L.)

Aims: To investigate the fermentation parameters physico-chemical characteristics and to conduct sensory evaluation to assess the acceptability of the fermented chia seeds. Study Design: Experimental study involving the fermentation of chia seeds with varying combinations of water, curd, and honey. Assessment of fermentation parameters and physico-chemical characteristics. Microbiological analysis, LAB isolation, and measurement of TSS, acidity, and pH. Sensory evaluation to determine the acceptability of the fermented chia seeds. Place and Duration of Study: The study undertaken during 2020-23 in the Department of Food Science and Nutrition, University of Agricultural Sciences, GKVK, Bangalore, Karnataka. Methodology: Chia seeds subjected to different fermentation treatments involving combinations of water, curd, and honey. Microbiological analysis conducted to assess microbial populations. Isolation of lactic acid bacteria (LAB) to study their presence. Measurement of total soluble solids (TSS), acidity, and pH to evaluate physico-chemical changes during fermentation. Sensory evaluation performed to determine consumer acceptability. Results: Fermentation treatments showed significant differences in soluble solids ranged (1.63 to 8.10), pH (1.87 to 3.87), and acidity, showcasing organic acid content, notably lactic acid (0.04 to 0.23), oxalic acids (0.04 to 0.23), citric acid (0.09 to 0.50), maleic acid (0.06 to 0.35) and succinic acid (0.05 to 0.30. Fermented white chia with distilled water + curd+ honey (FWC3) and Fermented black chia with distilled water + curd+ honey (FBC3) had the statistically higher mean sensory scores.

Valorization of rice straw and vascular aquatic weeds for sustainable prebiotic hemicellulosic autohydrolysate production: Extraction, characterization and fermentability.

This study describes the extraction and characterization of the hemicellulosic autohydrolysates (HAHs) derived from rice straw (RS) and vascular aquatic weeds like Typha angustifolia (TA) and Ceretophyllum demersum (CD). It further explores their capacity to sustain the proliferation of selected lactic acid bacteria (i.e., prebiotic activity) isolated from milk samples. To fractionate HAH from RS, TA and CD hot water extraction (HWE) method was used and RS, TA, and CD biomasses yielded 6.8, 4.99 and 2.98% of HAH corresponding to the hemicellulose extraction efficiencies of 26.15 ± 0.8%, 23.76 ± 0.6%, and 18.62 ± 0.4% respectively. The chemical characterization of HAH concentrates through HPLC showed that they comprised galactose, arabinose, xylose and glucose. The total phenol content of the RS, TA and CD-derived HAH concentrates were 37.53, 56.78 and 48.08mg GAE/g. The five lactic acid bacteria (LAB) isolates Q1B, Q2A, Q3B, G1C and G2B selected for prebiotic activity assays generated mixed responses with the highest growth in RS-HAH for Q2A and the least in TA-HAH for Q3B. Further, the isolates Q2A, Q3B, G1C, and G2B, which showed the highest growth performance, were identified through MALDI-TOF and 16S rRNA sequencing as Lactobacillus brevis. All the tested LAB isolates showed diauxic growth in crude HAH preparations to maximize the utilization of carbon resources for their proliferation. This suggests that the selected LAB isolates are efficient degraders of hemicellulosic sugars. This paves the way for the valorization of lignocellulosic biomass to produce prebiotic hemicellulosic autohydrolysate and consequently enhances environmental sustainability by improving resource efficiency.

Genotypic and Phenotypic Characteristics of Lactic Acid Bacteria Associated with Forage Plants in the Native Grassland of Western Inner Mongolia and Their Application for Alfalfa Silage Fermentation

This study was conducted to investigate the genotypic and phenotypic characteristics of lactic acid bacteria (LAB) associated with forage plants in the native grassland of western Inner Mongolia and to evaluate their effects on alfalfa silage fermentation. Forage plants and their spontaneous fermentation silages were analysed using culture-based techniques for LAB isolation; the phenotypic properties and 16S rDNA and pheS or rpoA gene sequences of the isolates were evaluated; alfalfa was ensiled with four additive combinations: Lactiplantibacillus plantarum subsp. plantarum (GI19), Lact. plantarum subsp. plantarum and Pediococcus pentosaceus (GI19+GI51), GI19 and 20 g/kg fresh matter of sucrose (GI19+S), and GI19+GI51+S, for 60 d. A total of 73 strains belonging to 16 species were isolated. All isolates grew at 5–45 °C and in 3.0% NaCl, and most of them grew in 6.5% NaCl. Enterococcus faecalis and Lact. plantarum were 26.03% and 17.81% of the total isolates, respectively. All additives improved the silage quality, while GI19+S was more effective for alfalfa ensiling with a higher lactic acid content and lower pH, undesirable microorganism counts, and acetic acid and NH3-N contents than remnant additives. In conclusion, the LAB species were diverse, and most of them possessed good cryotolerance and osmotolerance; GI19+S was the optimal inoculant for alfalfa fermentation improvement.

Identification of novel probiotic lactic acid bacteria from soymilk waste using the 16s rRNA gene for potential use in poultry

Background and Aim: In-feed antibiotics have been used as antibiotic growth promoters (AGPs) to enhance the genetic potential of poultry. However, the long-term use of AGPs is known to lead to bacterial resistance and antibiotic residues in poultry meat and eggs. To address these concerns, alternatives to AGPs are needed, one of which is probiotics, which can promote the health of livestock without having any negative effects. In vitro probiotic screening was performed to determine the ability of lactic acid bacteria (LAB) isolated from soymilk waste to be used as a probiotic for livestock. Materials and Methods: Four LAB isolates (designated F4, F6, F9, and F11) isolated from soymilk waste were used in this study. In vitro testing was performed on LAB isolates to determine their resistance to temperatures of 42°C, acidic pH, bile salts, hydrophobicity to the intestine, and ability to inhibit pathogenic bacteria. A promising isolate was identified using the 16S rRNA gene. Results: All LAB isolates used in this study have the potential to be used as probiotics. On the basis of the results of in vitro testing, all isolates showed resistance to temperatures of 42°C and low pH (2.5) for 3 h (79.87%–94.44%) and 6 h (76.29%– 83.39%), respectively. The survival rate at a bile salt concentration of 0.3% ranged from 73.24% to 90.39%, whereas the survival rate at a bile salt concentration of 0.5% ranged from 56.28% to 81.96%. All isolates showed the ability to attach and colonize the digestive tract with a hydrophobicity of 87.58%–91.88%. Inhibitory zones of LAB against pathogens ranged from 4.80–15.15 mm against Staphylococcus aureus, 8.85–14.50 mm against Salmonella enteritidis, and 6.75–22.25 mm against Escherichia coli. Although all isolates showed good ability as probiotics, isolate F4 showed the best probiotic ability. This isolate was identified as Lactobacillus casei strain T22 (JQ412731.1) using the 16S rRNA gene. Conclusion: All isolates in this study have the potential to be used as probiotics. However, isolate F4 has the best probiotic properties and is considered to be the most promising novel probiotic for poultry. Keywords: lactic acid bacteria, poultry, probiotic.

Identification of lactic acid bacteria found in traditional Shalgam juice using 16S rRNA sequencing and evaluation of their probiotic potential in vitro

This research focuses on the identification of lactic acid bacteria (LAB) isolated from traditionally produced Shalgam juices collected from different locations in Türkiye and the characterization of their probiotic potential in vitro. LAB isolates were identified by 16 S rRNA gene sequencing. The most common strains belonged to Pediococcus acidilactici (54.2%), Lacticaseibacillus sp. (18.8%), L. paracasei (8.3%) and Enterococcus faecalis (6.3%). According to the test results, LAB isolates survived after exposure to low pH (2.0) except Levilactobacillus brevis TS9 and P. acidilactici TS10. All isolates showed tolerance to bile salts (69.78%–147.84%), pepsin (50.10%–159.43%), pancreatin (46.64%–120.12%) and phenol (58.19%–121.84%) at various levels. The isolates E. faecalis TS2 and Lacticaseibacillus sp. TS3 were more resistant to the target microorganisms. The isolates E. faecalis TS2, L. paracasei TS7, P. acidilactici TS41, and P. acidilactici TS43 were highly resistant to the antibiotics. The hydrophobicity of the isolates toward xylene ranged from 2.32% to 58.56% and P. acidilactici TS42 showed a high hydrophobicity of 58.56%. The ability of auto-aggregation and co-aggregation varied from 3.59% to 23.67% and 0.85–29.37%, respectively. The isolates showing the best probiotic properties (Lacticaseibacillus sp. TS3, Lacticaseibacillus sp. TS11, and L. paracasei TS33) were tested for their ability to produce short-chain fatty acids. The acetate, butyrate and propionate production of the isolates varied between 4040 and 8135, 1025–1255 and 14620-17225 μg/mL, respectively. Butyrate production of the isolates were higher than the control group. These results indicated that LAB originated from Shalgam juice could be proposed as probiotic candidates for use in fermented foods.

Lacto-fermented garlic handcrafted in the Lower Silesia Region (Poland): Microbial diversity, morpho-textural traits, and volatile compounds

The aim of the present study was to provide a first characterization of lacto-fermented garlic manufactured by local small-scale artisanal producers in the Lower Silesia Region (Poland). The lacto-fermented garlic samples showed high nutritional features in terms of antioxidant activity. A total of 86 compounds, belonging to various chemical classes, were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS). Most of these compounds belonged to six main classes, being sulfur compounds, esters and acetates, oxygenated monoterpenes, monoterpene hydrocarbons, and alcohols. Aldehydes, acids, ketones, furans, and phenols were also identified. In the analyzed samples, counts up to 8 log cfu g−1 were observed for lactic acid bacteria. Metataxonomic analysis revealed the presence of Levilactobacillus, Lactiplantibacillus, Latilactobacillus, Secundilactobacillus, Weissella, Leuconostoc, Lactococcus, Pediococcus, and Lacticaseibacillus among the major taxa. These results were confirmed by the isolation and characterization of viable lactic acid bacteria. Indeed, the presence of the closest relatives to Lacticaseibacillus casei group, Pediococcus parvulus, Levilactobacillus brevis, Levilactobacillus parabrevis, and Lactiplantibacillus plantarum group was observed. A good acidification performance in salty garlic-based medium was observed for all the isolates that, between 8 and 15 days of fermentation, reached pH values comprised between 4 and 3.5, depending on the tested species. Of note, 15 out of the 37 lactic acid bacteria isolates (Levilactobacillus parabrevis, Pediococcus parvulus, Lactiplantibacillus plantarum group, and Lacticaseibacillus casei group) showed the presence of the hdcA gene of Gram-positive bacteria encoding for histidine decarboxylase. Furthermore, for 8 out of the 37 isolates the in-vitro exopolysaccharides production was observed. No isolate showed inhibitory activity against the three Listeria innocua strains used as surrogate for Listeria monocytogenes.

Screening of a potential probiotic Lactiplantibacillus plantarum NUC08 and its synergistic effects with yogurt starter

This study aims to identify lactic acid bacteria (LAB) isolates possessing physiological characteristics suitable for use as probiotics in yogurt fermentation. Following acid and bile salt tolerance tests, Lactiplantibacillus plantarum (NUC08 and NUC101), Lacticaseibacillus rhamnosus (NUC55 and NUC201), and Lacticaseibacillus paracasei (NUC159, NUC216 and NUC351) were shortlisted based on intraspecies distribution for further evaluation. Their physiological probiotic properties, including transit tolerance, adhesion, auto-aggregation, surface hydrophobicity, biofilm formation, and antibacterial activity, were assessed. Principal Component Analysis (PCA) indicated that L. plantarum NUC08 was the preferred choice among the evaluated strains. Subsequent investigations revealed that co-culturing L. plantarum NUC08 with 2 yogurt starter strains resulted in a cooperative and synergistic effect, enhancing the growth of mixed strains and increasing their tolerance to simulated gastric and intestinal conditions. Additionally, when Vibrio harveyi bioluminescent reporter strain was used, the 3 cocultured strains cooperated to induce the activity of a quorum sensing (QS) molecule AI-2, hinting a potential connection between phenotypic traits and QS in the cocultured strains. Importantly, LAB viable counts were significantly higher in yogurt co-fermented with L. plantarum NUC08, consistently throughout the storage period. In conclusion, the study demonstrates that the probiotic strain L. plantarum NUC08 can be employed in synergy with yogurt starter strains, affirming its potential for use in the development of functional fermented dairy products.

Controlled fermented sprouted mung bean containing ginger extract as a novel bakery bio-preservative for clean-label enriched wheat bread

Application of controlled fermented sprouted legumes is important in terms of improving quality and shelf-life of wheat bread. In the present study, after spontaneous fermentation of sprouted mung bean containing ginger extract (GE), the predominant lactic acid bacteria (LAB) isolates were screened based on their inhibitory activity against Aspergillus niger. Sequencing results of the PCR products led to the identification of Levilactobacillus brevis as the selected isolate with 73.12% antifungal effect. Then, the selected isolate was used as a protective starter culture in the controlled fermented sprouted mung bean (FSM). Production of wheat bread with FSM containing a protective starter culture and GE not only improved the textural features of the product, but also increased its mold-free shelf-life. Accordingly, wheat bread containing FSM and GE with crumb hardness of 9.52 N, specific volume of 3.53 cm3/g and weight loss of 15.95% had the most appropriate textural characteristics with the lowest fungal surface expansion (45.52% mold growth) after 7 days storage in a challenge test. Furthermore, there was no significant difference (P>0.05) between this sample and control bread in terms of overall acceptability.

Selection of starter lactic acid bacteria capable of forming biofilms on wooden vat prototypes for their future application in traditional Sicilian goat's milk cheese making

In this study, 327 presumptive lactic acid bacteria (LAB) were isolated from goats' milk acid curds produced at a Sicilian dairy farm with the aim to identify potential starter cultures for traditional cheeses. All isolates were first processed by randomly amplified polymorphic DNA (RAPD)-PCR analysis. This approach identified 63 distinct strains which were evaluated for their acidifying capacity. Only 15 strains specifically stood out for their acidification capacity and were identified through 16S rRNA gene sequencing as Lactococcus lactis (11 strains) Enterococcus faecalis (three strains), and Ligilactobacillus animalis (one strain). Notably, all 15 LAB isolates produced bacteriocin-like inhibitory substances and anti-biofilm compounds, against both planktonic and biofilm forms of Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli, and Staphylococcus aureus, albeit at varying levels. Among these 15 LAB, En. faecalis RGM25 and Lc. lactis RGM55, susceptible to five antibiotics tested, were put in contact with wooden vat prototypes, because all equipment used in traditional cheese production in Sicily are made of wood. Scanning electron microscopy and bacterial plate counts of the wooden vat prototypes showed the development of biofilms at levels of approximately 6.0 log CFU/cm2. Overall, this study contributes to establishing a custom-made LAB starter cultures with bio-preservatives properties for Sicilian cheese productions.

Synergistic Inhibition of Synbiotic Cultures among Lactobacilli and Plant Extracts against Vaginal Discharge Causing Candida albicans.

Vulvovaginal candidiasis (VVC) is the most common cause of vaginal discharge among women. The present study aimed to investigate the synergistic anticandidal effect of lactobacillus cultures supplemented with plant extracts. Among 600 isolates of lactic acid bacteria, 41 isolates exhibited inhibitory activity against Candida albicans ATCC10231. Six out of 41 cell-free supernatants demonstrated the most potent antibacterial and anticandidal activities. They also inhibited the clinical isolates of C. albicans, causing VVC and non-C. albicans. The synergistic effect between Lactobacillus crispatus 84/7 and Limosilactobacillus reuteri 89/4 was demonstrated by the lowest fractional inhibitory concentration index (FICI = 0.5). The synbiotic culture of bacterial combination, cultured with Jerusalem artichoke (H. tuberosus) extract, also exhibited the strongest inhibition against the tested C. albicans. Biofilm formation decreased after 12 h of incubation in the selected cell-free supernatants of this synbiotic culture. The anticandidal activity of crude extracts was lost after treatment with proteinase K and trypsin but not with heating conditions, suggesting that it may be a heat-stable substance. In conclusion, the combination of L. crispatus 84/7 and L. reuteri 89/4 with H. tuberosus may be a promising candidate for inhibiting Candida infection and biofilm formation, with the potential use as ingredients in vaginal biotherapeutic products.

Isolation of Amylolytic Lactic Acid Bacteria from Cow, Goat and Sheep Milk in Yola Town, Adamawa State, Nigeria

In this study, lactic acid bacteria (LAB) were isolated from fresh milk samples from cow, sheep, and goat using MRS agar as a growth medium. Lactobacillusplantarum, Lactobacillusacidophilus, Lactobacillusfermentum, Enterococcusgallinarum, and Enterococcusfaecium were the species of LAB that were isolated and identified using the Vitek 2 compact system. While Lactobacillus fermentum, Enterococcus faecium, and Lactobacillus plantarum were isolated from goat milk, Lactobacillus acidophilus, Lactobacillus gallinarum, and Lactobacillus plantarum were isolated from cow milk.However, from sheep milk, only Lactobacillus plantarum and Lactobacillus acidophilus were isolated. All the isolates were subjected to amylase production test using modified MRS media and the results showed that Lactobacillus plantarum, Lactobacillusacidophilus and Lactobacillusfermentum produced amylase while Enterococcus gallinarum and Enterococcus faecium did not produce amylase.

Application of selected lactic acid bacteria isolates for bread production without baker’s yeast

Application of selected lactic acid bacteria isolates for bread production without baker’s yeast

Investigating human-derived lactic acid bacteria for alcohol resistance

BackgroundExcessive alcohol consumption has been consistently linked to serious adverse health effects, particularly affecting the liver. One natural defense against the detrimental impacts of alcohol is provided by alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), which detoxify harmful alcohol metabolites. Recent studies have shown that certain probiotic strains, notably Lactobacillus spp., possess alcohol resistance and can produce these critical enzymes. Incorporating these probiotics into alcoholic beverages represents a pioneering approach that can potentially mitigate the negative health effects of alcohol while meeting evolving consumer preferences for functional and health-centric products.ResultsFive lactic acid bacteria (LAB) isolates were identified: Lactobacillus paracasei Alc1, Lacticaseibacillus rhamnosus AA, Pediococcus acidilactici Alc3, Lactobacillus paracasei Alc4, and Pediococcus acidilactici Alc5. Assessment of their alcohol tolerance, safety, adhesion ability, and immunomodulatory effects identified L. rhamnosus AA as the most promising alcohol-tolerant probiotic strain. This strain also showed high production of ADH and ALDH. Whole genome sequencing analysis revealed that the L. rhamnosus AA genome contained both the adh (encoding for ADH) and the adhE (encoding for ALDH) genes.ConclusionsL. rhamnosus AA, a novel probiotic candidate, showed notable alcohol resistance and the capability to produce enzymes essential for alcohol metabolism. This strain is a highly promising candidate for integration into commercial alcoholic beverages upon completion of comprehensive safety and functionality evaluations.

CLI: A new protocol for the isolation of Lactic Acid Bacteria from complex plant samples

Lactic Acid Bacteria (LAB) are predominantly probiotic microorganisms and the most are Generally Recognized As Safe (GRAS). LAB inhabit in the human gut ecosystem and are largely found in fermented foods and silage. In the last decades, LAB have also has been found in plant microbiota as a new class of microbes with probiotic activity to plants. For this reason, today the scientific interest in the study and isolation of LAB for agronomic application has increased. However, isolation protocols from complex samples such as plant tissues are scarce and inefficient.In this study, we developed a new protocol (CLI, Complex samples LAB Isolation) which yields purified LAB from plants. The sensitivity of CLI protocol was sufficient to isolate representative microorganisms of LAB genera (i.e. Leuconostoc, Lactococcus and Enterococcus).CLI protocol consists on five steps: i) sample preparation and pre-incubation in 1% sterile peptone at 30 °C for 24–48 h; ii) Sample homogenization in vortex by 10 min; iii) sample serial dilution in quarter-strength Ringer solution, iv) incubation in MRS agar plates with 0.2% of sorbic acid, with 1% of CaCO3, O2 < 15%, at pH 5.8 and 37 °C for 48 h.; v) Selection of single colonies with LAB morphology and CaCO3-solubilization halo. Our scientific contribution is that CLI protocol could be used for several complex samples and represents a useful method for further studies involving native LAB.

Phenotypic and genotypic characterization of antimicrobial resistances reveals the effect of the production chain in reducing resistant lactic acid bacteria in an artisanal raw ewe milk PDO cheese

Antimicrobial resistance (AMR) is a significant public health threat, with the food production chain, and, specifically, fermented products, as a potential vehicle for dissemination. However, information about dairy products, especially raw ewe milk cheeses, is limited. The present study analysed, for the first time, the occurrence of AMRs related to lactic acid bacteria (LAB) along a raw ewe milk cheese production chain for the most common antimicrobial agents used on farms (dihydrostreptomycin, benzylpenicillin, amoxicillin and polymyxin B). More than 200 LAB isolates were obtained and identified by Sanger sequencing (V1-V3 16S rRNA regions); these isolates included 8 LAB genera and 21 species. Significant differences in LAB composition were observed throughout the production chain (P ≤ 0.001), with Enterococcus (e.g., E. hirae and E. faecalis) and Bacillus (e.g., B. thuringiensis and B. cereus) predominating in ovine faeces and raw ewe milk, respectively, along with Lactococcus (L. lactis) in whey and fresh cheeses, while Lactobacillus and Lacticaseibacillus species (e.g., Lactobacillus sp. and L. paracasei) prevailed in ripened cheeses. Phenotypically, by broth microdilution, Lactococcus, Enterococcus and Bacillus species presented the greatest resistance rates (on average, 78.2 %, 56.8 % and 53.4 %, respectively), specifically against polymyxin B, and were more susceptible to dihydrostreptomycin. Conversely, Lacticaseibacillus and Lactobacillus were more susceptible to all antimicrobials tested (31.4 % and 39.1 %, respectively). Thus, resistance patterns and multidrug resistance were reduced along the production chain (P ≤ 0.05). Genotypically, through HT-qPCR, 31 antimicrobial resistance genes (ARGs) and 6 mobile genetic elements (MGEs) were detected, predominating Str, StrB and aadA-01, related to aminoglycoside resistance, and the transposons tnpA-02 and tnpA-01. In general, a significant reduction in ARGs and MGEs abundances was also observed throughout the production chain (P ≤ 0.001). The current findings indicate that LAB dynamics throughout the raw ewe milk cheese production chain facilitated a reduction in AMRs, which has not been reported to date.

Isolation and Identification of Chicken-Derived Lactic Acid Bacteria: In Vitro Probiotic Properties and Antagonistic Effects against Salmonella pullorum, Staphylococcus aureus, and Escherichia coli.

The development of probiotics capable of quickly colonizing the intestines of animals is important in promoting the healthy growth of livestock. The aim of this study was to screen lactic acid bacteria (LAB) from the intestinal microbiota of chickens with potential applications, and to evaluate their probiotic properties and antagonistic abilities against Salmonella pullorum, Staphylococcus aureus, and Escherichia coli. The results showed that a total of 79 strains with the characteristics of LAB were isolated from the chicken cecum microbiota, of which 7 strains exhibited strong inhibitory activity against S. pullorum, S. aureus, and E. coli. Performing 16s rDNA sequencing revealed that these seven strains were Lactiplantibacillus pentosus (n = 1), Lactiplantibacillus plantarum (n = 3), Lactiplantibacillus paraplantarum (n = 1), Lactiplantibacillus argentoratensis (n = 1), and Lactiplantibacillus fabifermentans (n = 1). Among them, L. pentosus R26 and L. plantarum R32 exhibited superior antibacterial activity. These two strains demonstrated high lactic acid production ability, with survival rates of 86.29% and 87.99% after 3 h of treatment at pH 1.5, 86.66% and 85.52% after 3 h of treatment with 0.5% bile salts, 90.03% and 88.16% after 2 h of treatment with simulated gastric fluid, and 98.92% and 98.22% after 2 h of treatment with simulated intestinal fluid, respectively. Co-cultivation with L. pentosus R26 for 24 h resulted in 50% of the pathogens being antagonized, while almost complete inhibition was observed following 72 h of co-cultivation. In conclusion, L. pentosus R26 and L. plantarum R32 exhibited high antibacterial activity and acid production capability, while also demonstrating satisfactory tolerance to low pH values and high concentrations of bile salts and digestive fluid. The probiotic characteristics and stress resistance of L. pentosus R26 were slightly superior to those of L. plantarum R32, indicating its potential for development as a probiotic.

Cereus jamacaru DC. (mandacaru) fruit as a source of lactic acid bacteria with in vitro probiotic-related characteristics and its protective effects on Pediococcus pentosaceus during lyophilization and refrigeration storage

This study isolated and identified autochthonous lactic acid bacteria (LAB) from mandacaru fruit and evaluated their potential probiotic and technological aptitudes in vitro, as well as the protective effects of freeze-dried mandacaru fruit on the most promising LAB isolate during lyophilization and refrigeration storage. Initially, 212 colonies were isolated from mandacaru fruit, and 34 were preliminarily identified as LAB. Thirteen isolates identified by 16S-rRNA sequencing as Pediococcus pentosaceus were negative for DNase, gelatinase, hemolytic, and biogenic amine production. The selected isolates showed proteolytic activity, diacetyl and exopolysaccharide production, and good tolerance to different NaCl concentrations while having low cellular hydrophobicity and antagonistic activity against pathogens. The survival of isolates sharply decreased after 3 h of exposure to pH 2 and had a good tolerance to 1 % bile salt. A principal component analysis selected P. pentosaceus 57 as the most promising isolate based on the examined technological and probiotic-related physiological properties. This isolate was lyophilized with mandacaru fruit and stored under refrigeration for 90 days. P. pentosaceus 57 lyophilized with mandacaru fruit had high viable cell counts (9.69 ± 0.03 log CFU/mL) and >50 % of physiologically active cells at 90 days of refrigeration storage. The results indicate that mandacaru fruit is a source of P. pentosaceus with aptitudes to be explored as potential probiotic and technological characteristics of interest for the food industry, besides being a good candidate for use in lyophilization processes and refrigeration storage of LAB due to its cryoprotective effects.

Investigation of the antidiabetic and probiotic properties of lactic acid bacteria isolated from some ethnic fermented foods of Darjeeling District

BackgroundIndigenous communities residing in the Darjeeling Himalayan region and its adjacent hilly areas have a deeply rooted cultural tradition of consuming a diverse range of vegetable and milk-based fermented products, believed to confer various health advantages. With this traditional knowledge, lactic acid bacteria (LAB) were isolated from popular fermented foods such as Chhurpi (derived from Bos grunniens milk), Gundruk (made from Brassica juncea leaves), Sinki (derived from Raphanus sativus taproots), and Kinema (produced from Glycine max beans). This study aimed to investigate the probiotic properties of the prevalent LABs, including aggregation properties, bile salt hydrolase activities, survival under gastro-inhibitory conditions, safety evaluations, and their potential health-promoting attributes, with a specific focus on inhibiting α-amylase and α-glucosidase enzymes.ResultsFive of the LAB isolates demonstrated notable viability rates exceeding 85% when exposed to gastro-inhibitory challenges. Based on 16S rRNA gene sequencing, these isolates were identified as Pediococcus pentosaceus (isolate GAD), Lactobacillus plantarum (isolates KAD and CAD), Lactobacillus brevis (isolate SAD), and Lactiplantibacillus plantarum (isolate CMD). These LAB isolates exhibited versatile carbon source utilization, significant auto- and co-aggregation, and bile salt hydrolase (BSH) properties. Auto-aggregation capacity notably increased over time, ranging from 30 to 150 min, with percentage increments from 4.83 ± 1.92% to 67.60 ± 5.93%. L. brevis SAD displayed the highest co-aggregation increment (%) against Staphylococcus aureus, while L. plantarum KAD demonstrated potent antimicrobial activity. In vitro analyses postulated potential health benefits related to antidiabetic properties, particularly inhibiting α-amylase and α-glucosidase enzymes. L. brevis SAD exhibited the highest α-glucosidase inhibitory activity, while L. plantarum KAD displayed the most potent α-amylase inhibitory activity. Comprehensive safety assessments, including antibiotic susceptibility profiling, hemolytic activity evaluation, and in vivo acute toxicity studies, confirmed the suitability of these LAB isolates for human consumption.ConclusionsThe isolates show promising probiotic characteristics and significant potential in addressing metabolic health. These results carry substantial scientific implications, suggesting the pharmaceutical-based applications of these traditional fermented foods. Further in vivo investigation is recommended to fully elucidate and exploit the health benefits of these LAB isolates, opening avenues for potential therapeutic interventions and the development of functional foods.