Lactic Acid Bacteria Strains Research Articles

Hypothetical Regulation of Folate Biosynthesis and Strategies for Folate Overproduction in Lactic Acid Bacteria.

Folate (vitamin B9) is an essential nutrient for cell metabolism, especially in pregnant women; however, folate deficiency is a major global health issue. To address this issue, folate-rich fermented foods have been used as alternative sources of natural folate. Lactic acid bacteria (LAB), which are commonly involved in food fermentation, can synthesize and excrete folate into the medium, thereby increasing folate levels. However, screening for folate-producing LAB strains is necessary because this ability is highly dependent on the bacterial strain. Some strains of LAB consume folate, and their presence in a fermentation mix can lower the folate levels of the final product. Since microorganisms efficiently regulate folate biosynthesis to meet their growth needs, some strains of folate-producing LAB can deplete folate levels if folate is available in the media. Such folate-efficient producers possess a feedback inhibition mechanism that downregulates folate biosynthesis. Therefore, the application of folate-overproducing strains may be a key strategy for increasing folate levels in media with or without available folate. Many studies have been conducted to screen folate-producing bacteria, but very few have focused on the identification of overproducers. This is probably because of the limited understanding of the regulation of folate biosynthesis in LAB. In this review, we discuss the roles of folate-biosynthetic genes and their contributions to the ability of LAB to synthesize and regulate folate. In addition, we present various hypotheses regarding the regulation of the feedback inhibition mechanism of folate-biosynthetic enzymes and discuss strategies for obtaining folate-overproducing LAB strains.

ANTIFUNGAL ACTIVITY OF Pediococcus pentosaceus ISOLATED FROM BAMBARA GROUNDNUT (Vigna subterranea (L.) Verdc.) SEEDS AGAINST Aspergillus flavus

In this study, 22 lactic acid bacterial (LAB) strains were isolated from Bambara groundnut seeds and assessed for their ability to suppress the development of two strains of aflatoxigenic Aspergillus flavus. The antifungal activity of LAB strains was assessed via the overlay assay. Also, HPLC methodology was used to quantify the production of lactic and acetic acid by the LAB strains with high antifungal activity. After incubation at 30°C for 72 hours, five of these LAB strains (52B1, 52C1, 74B3, 67B1, 67A9) showed high inhibitory activity against Aspergillus flavus strains. These LAB strains exhibiting antifungal potential were identified as Pediococcus pentosaceus through 16S rDNA sequencing. Furthermore, the lactic acid bacteria (LAB) strains reported lactic acid production ranging from 12.08 mg/ml to 15.38 mg/ml and acetic acid production ranging from 0.06 mg/ml to 1.68 mg/ml. Notably, antifungal experiments are conducted in a controlled setting. Further, it would be worthwhile to explore the direct application of Pediococcus pentosaceus strains or their antimicrobial agents to food products to prevent fungal growth during storage. By doing so, the use of fungicides can be avoided and lead to safer food products.

Isolation, characterization of Weissella confusa and Lactococcus lactis from different milk sources and determination of probiotic features.

This study aimed to investigate the probiotic properties of Lactic Acid Bacteria (LAB) isolates derived from various milk sources. These isolates identified based on their morphological characteristics and 16S rRNA gene sequencing. Four strains of Lactococcus lactis and two strains of Weissella confusa were identified with over 96% 16S rRNA gene similarity according to the NCBI-BLAST results. The survival of the isolates was determined in low pH, pepsin, bile salts, and pancreatin, and their adhesion ability was assessed by in vitro cell adhesion assay, hydrophobicity, auto- and co-aggregation, and safety criteria were determined by hemolytic, gelatinase activities, and DNAse production ability tests. The results showed that the LAB isolates had different levels of resistance to various stress factors. L. lactis subsp. cremoris MH31 showed the highest resistance to bile salt, while the highest pH resistance was observed in L. lactis MH31 at pH 3.0. All the isolates survived in pepsin exposure at pH 3.0 for 3h. The auto-aggregation test results showed that all strains exhibited auto-aggregation ranging from 84.9 to 91.4%. Co-aggregation percentage ranged from 19 - 54% and 17 - 57% against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, respectively. The hydrophobicity capacity of the LAB isolated ranged from 35-61%. These isolates showed different adhesion abilities to Caco-2 cells (81.5% to 92.6%). None of the isolates exhibited DNase, gelatinase and hemolytic activity (γ-hemolysis). All results indicate that these LAB strains have the potential to be used as probiotics.

Phosphate solubilization and plant growth properties are promoted by a lactic acid bacterium in calcareous soil.

On the basis of good phosphate solubilization ability of a lactic acid bacteria (LAB) strain Limosilactobacillus sp. LF-17, bacterial agent was prepared and applied to calcareous soil to solubilize phosphate and promote the growth of maize seedlings in this study. A pot experiment showed that the plant growth indicators, phosphorus content, and related enzyme activity of the maize rhizospheric soils in the LF treatment (treated with LAB) were the highest compared with those of the JP treatment (treated with phosphate solubilizing bacteria, PSB) and the blank control (CK). The types of organic acids in maize rhizospheric soil were determined through LC-MS, and 12 acids were detected in all the treatments. The abundant microbes belonged to the genera of Lysobacter, Massilia, Methylbacillus, Brevundimonas, and Limosilactobacillus, and they were beneficial to dissolving phosphate or secreting growth-promoting phytohormones, which were obviously higher in the LF and JP treatments than in CK as analyzed by high-throughput metagenomic sequencing methods. In addition, the abundance values of several enzymes, Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology, and Carbohydrate-Active Enzymes (CAZys), which were related to substrate assimilation and metabolism, were the highest in the LF treatment. Therefore, aside from phosphate-solubilizing microorganisms, LAB can be used as environmentally friendly crop growth promoters in agriculture and provide another viable option for microbial fertilizers. KEY POINTS: • The inoculation of LAB strain effectively promoted the growth and chlorophyll synthesis of maize seedlings. • The inoculation of LAB strain significantly increased the TP content of maize seedlings and the AP concentration of the rhizosphere soil. • The inoculation of LAB strain increased the abundances of the dominant beneficial functional microbes in the rhizosphere soil.

Some enzymatic properties of lactic acid bacteria isolated from dairy products

This article presents data on the study of physiological and biochemical properties, antagonistic and enzymatic activity of lactic acid bacteria isolated from dairy products.9 types of lactic acid bacteria were studied:Lactobacillus bulgaricus GM – 08, Lactobacillus bulgaricus KZh – 01,Lactobacillus bulgaricus GS – 03, Lactococcus cremoris – 6, Lactococcus cremoris – 17, Lactococcus cremoris – 26, Lactococcus lactis – 1,Lactococcus lactis – 15, Lactococcus lactis – 23. These strains were found to have resistance to 2% and 4%-vertical NaCl concentrations, bile and phenol.In addition, the antagonistic activity of Gram-positive and Gram-negative microorganisms in relation to test cultures of Staphylococcus aureus, Salmonella dublin, Escherichia coli, Bacillus subtilis, Sarcina flava was studied.All studied lactic acid bacteria showed activity in Test cultures with different inhibition zones. The Lactococcus lactis – 23 strains showed high activity for all cultures, with an inhibition zone of 17-25 mm.Further, 5 strains were selected from these strains and their aroma-forming properties, the formation of diacetyl and ammonia from arginine, hemolytic and lecithinase activity were studied.Compositions were compiled from these strains to make yeast.The compatibility of strains of lactic acid bacteria was checked with each strain individually and with the duration of milk clotting according to organoleptic indicators compared to the duration of milk clotting.Thus, the most active clot formation was obtained by the Lactococcus lactis – 23 strainof the selected combinations.

Non-volatile and volatile compound changes in blueberry juice inoculated with different lactic acid bacteria strains.

Lactic acid bacteria (LABs) are widely present in foods and affect the flavour of fermented cultures. This study investigates the effects of fermentation with Lactobacillus acidophilus JYLA-16 (La), Lactobacillus plantarum JYLP-375 (Lp), and Lactobacillus rhamnosus JYLR-005 (Lr) on the flavour profile of blueberry juice. This study showed that all LABs strains preferentially used glucose rather than fructose as the carbon source during fermentation. Lactic acid was the main fermentation product, reaching 7.76 g L-1 in La-fermented blueberry juice, 5.86 g L-1 in Lp-fermented blueberry juice, and 6.41 g L-1 in Lr-fermented blueberry juice. These strains extensively metabolized quinic acid, whereas oxalic acid metabolism was almost unaffected. Sixty-four volatile compounds were identified using gas chromatography-ion mobility spectrometry (GC-IMS). All fermented blueberry juices exhibited decreased aldehyde levels. Furthermore, fermentation with La was dominated by alcohols, Lp was dominated by esters, and Lr was dominated by ketones. Linear discriminant analysis of the electronic nose and principal component analysis of the GC-IMS data effectively differentiated between unfermented and fermented blueberry juices. This study informs LABs selection for producing desirable flavours in fermented blueberry juice and provides a theoretical framework for flavour detection. © 2023 Society of Chemical Industry.

Isolation and characterization of plant-based lactic acid bacteria from spontaneously fermented foods using a new modified medium

The development of starter cultures tailored to different plant-based materials plays a crucial role in achieving better fermented plant-based dairy alternatives (PBDA). Therefore, the isolation and study of new plant-based lactic acid bacteria (LAB) strains is essential. In this study, we developed a new medium for LAB isolation. Results showed this medium supported faster growth for all the 23 tested model strains, compared to the growth on M17 or MRS. Using the newly developed medium, 136 LAB strains belonging to 23 species and 11 genera were isolated from 73 spontaneously fermented food samples after a rigorous de-replication process. In addition, uptake of plant-based carbohydrates were studied. Only four strains were able to ferment all tested sugars efficiently. Furthermore, the production of butter aroma compounds in fermented commercial PBDA, including coconut, oat, rice, hemp, pea, hazelnut, and soy milk was also determined. These results demonstrated significant variations in the performance of fermenting PBDA by using different strains, with E. casseliflavus and L. sakei identified as efficient butter aroma producers in most of the tested conditions. Notably, certain strains also exhibited different behaviors when fermenting different substrates. The findings may provide valuable insights into developing new non-dairy fermented cultures with desired attributes.

Influence of Some Growth Conditions on The Antibacterial Activities of Lactobacillus fermentum Against Human Fecal Staphylococcus aureus

One of the best-known and widespread bacterial pathogens that cause invasive infections as well as skin infections is recognized as Staphylococcus aureus strains to contribute to certain pneumonia and other respiratory tract infections, cardiovascular infections, infections at surgical sites, infections of prosthetic joints, and nosocomial bacteremia. Meanwhile, Lactic acid bacteria (LAB) have an effective antibacterial potential that may be used to safeguard both human and animal health, according to several research. Numerous LAB strains are side effect free and incapable of harming both people and lab animals. Hence, this study was performed to investigate the optimal conditions including MipH, InTe, and InTi for Lactobacillus fermentum (LAF) isolated from traditional fermented foods against human fecal Staphylococcus aureus (hf-SA).

APPLICATION OF WHEY PROTEIN HYDROLYSATES AS A FERMENTATION MEDIUM WITH STRAINS OF LACTIC ACID BACTERIA

The aim of the present study is to obtain enzymatic hydrolysates from whey protein and evaluate their potential application as a substrate for fermentation with lactic acid bacteria. For hydrolysis of whey proteins, papain is used in 3 concentrations - 0.1, 0.5 and 1.0 mg mL-1. The degree of hydrolysis (DH) was determined on the obtained whey protein hydrolysates (WPHs), the highest percentage being achieved with hydrolysate WPH3 using the papain enzyme at a concentration of 1 mg mL-1. Fermentation of the whey protein hydrolysates was carried out with the participation of the probiotic strains Lactiplantibacillus plantarum subsp. plantarum NBIMCC 3447 and Lactobacillus gasseri NBIMCC 2450. The survival of two strains of probiotic lactic acid bacteria was investigated. In the samples obtained from hydrolyzed whey medium with 0.5 mg mL-1papain, the highest values of viable probiotic bacterial cells were recorded - for Lactiplantibacillus plantarum NBIMCC 3447 2.5 х 109 CFU mL-1, and for Lactobacillus gasseri NBIMCC 2450 2.1 х 109 CFU mL-1, respectively. Antioxidant activity is reported on the fermented products. The WPH2 variant has the highest antioxidant potential - 9.14 mg TE/100 mL.

Immunomodulatory Activity Analyses of Cell-Free Supernatant of Lactobacillus plantarum LP299v Strain in RAW 264.7 Macrophage Cells

The human immune system is essential for defending the body against harmful internal and external elements; immunity includes innate and acquired immunity. Macrophages, the innate immune system's key components, are crucial for the clearance of dead cells and tumor cells, as well as foreign substances by triggering phagocytosis. They also play a role in the adaptive response with the cytokines and mediator molecules they secrete. Lactic acid bacteria (LAB), an important probiotics class, have a strong potential to improve host health and can be used as a functional food. There have been reports of certain LAB strains having immunostimulating effects. However, the effects of cell-free supernatants (CFS) gathered from some LAB strains on macrophage activation have become an important research area in recent years. This study's main objective was to characterize the immunostimulatory activities of Lactobacillus plantarum LP299v in the RAW 264.7 macrophage cell line. For this purpose, the immunomodulatory activity of CFS of the related strain was evaluated by MTT, neutral red assay, and Griess reaction respectively, in terms of proliferation, phagocytosis ability, and nitric oxide (NO) production parameters using the macrophage cell line. Studies have shown that this strain significantly increased proliferation, phagocytosis, and NO levels in RAW264.7 macrophage cells. When considered, these results suggest that the cell-free supernatant, obtained from Lactobacillus plantarum LP299v selected in this study, may be helpful for candidate compounds with immunostimulatory activity.

Riboflavin bio-enrichment of soy beverage by selected roseoflavin-resistant and engineered lactic acid bacteria

Some lactic acid bacteria (LAB) have the ability to synthesize riboflavin, a trait linked to the presence of ribG, ribB, ribA and ribH genes located in the rib operon. Previous screening of riboflavin producers identified several LAB strains belonging to different species with this ability, but none of them surpassed 0.25 mg/L production of the vitamin. In this study, we explored two strategies to obtain riboflavin-overproducing strains: by roseoflavin selection of mutants, and by the transformation of selected strains with plasmids pNZ:TuR.rib or pNZ:TuB.rib containing the genes ribG, ribB, ribA and ribH from Lactococcus cremoris MG1363. The resulting riboflavin-overproducing strains were able to produce yields between 0.5 and 6 mg/L in culture media and several of them were selected for the fermentation of soy beverages. Riboflavin in bio-enriched soy beverages was evaluated by direct fluorescence measurement and high-performance liquid chromatography-fluorescence analysis. Soy beverages fermented with the recombinant strains Lactococcus cremoris ESI 277 pNZ:TuB.rib and Lactococcus lactis INIA 12 pNZ:TuR.rib showed the highest riboflavin yields (>5 mg/L) after 24 h fermentation. On the other hand, roseoflavin-resistant mutant Limosilactobacillus fermentum INIA P143R2 was able to enrich fermented soy beverages with 1.5 mg/L riboflavin. Riboflavin-overproducing LAB strains constitute a good option for riboflavin enrichment of soy beverages by fermentation and the commercialization of such beverages could be very useful to prevent riboflavin deficiency.

Reduction of malic acid in bilberry juice by Lactiplantibacillus plantarum-mediated malolactic fermentation

AbstractBilberries (Vaccinium myrtillus) are the most common wild berries in Northern Europe. A substantial amount of the berries are picked with the objective to extract highly valued products such as anthocyanins. A smaller amount of the bilberries is used to make jams and drinks, and these are generally restricted to the domestic market. One reason is the sour taste, partly as a result of the high content of malic acid. By using certain strains of lactic acid bacteria with the ability to convert malic acid to lactic acid, the taste is predicted to be more pleasant. This process is called malolactic fermentation, and historically it has mostly been used in winemaking. After testing five different starter cultures, we identified that the strain, Lactiplantibacillus plantarum LP58, can rapidly convert malic acid to lactic acid without any loss of sugar or citric acid, which strongly indicates a successful malolactic acid fermentation. As it has been reported that other strains of L. plantarum can be used as biopreservative agents, the resulting product was also tested in terms of microbial safety after prolonged storage, and by means of metagenome sequencing. The obtained product was quite tolerant to microbial growth, but this observation was rather due to an initial heat treatment than the addition of lactobacilli. Potentially, starter cultures with documented biopreservative activity can be combined with L. plantarum LP58 to obtain a more stable product. Until then, the fermented bilberry juice must be processed and preserved like non-fermented bilberry products.

Bacteriocinogenic Lacticaseibacillus paracasei strains from Inner Mongolian fermented milk efficiently control pathogenic bacteria in model cheddar-like cheese

Bacteriocins produced by lactic acid bacteria (LAB) consist of a wide range of antimicrobial proteins or peptides which can be used as bio-preservatives to control food-borne pathogens. In this study, bacteriocinogenic LAB strains were isolated from fermented milk in Inner Mongolia, China. These strains exhibited high antimicrobial activity and were identified as Lacticaseibacillus paracasei. The sensitivity of their antimicrobial activity to protease K implies the possible existence of bacteriocins within the culture. Selected L. paracasei strains were subjected to whole genome sequencing and the bacteriocin biosynthetic gene clusters were identified in-silico. To further verify the antimicrobial properties of the isolated strains in controlling food pathogens in model Cheddar-like cheese, they were used as adjunct starter cultures in cheese contaminated with Bacillus cereus and Listeria monocytogenes. The results showed that each of the five strains carries a minimum of three bacteriocins biosynthetic gene clusters. All L. paracasei strains exhibited the ability to inhibit B. cereus and L. monocytogenes and caused a significant log reduction of pathogens during cheese ripening. Additionally, the isolated strains improved cheese texture and flavor to varying degrees. In conclusion, the indigenious L. paracasei present in milk could play an important role in pathogen control and the quality improvement of Cheddar-like cheeses.

Lactic acid production from cashew apple bagasse, an agro-industrial waste, and its application in the enzymatic synthesis of polylactic acid

The use of cashew apple bagasse hemicellulose hydrolysate (CABH) to produce lactic acid by two strains of lactic acid bacteria, Lactobacillus plantarum FJ05311 and L. plantarum FJ05315, was evaluated. The application of cashew apple bagasse (CAB) would enhance the establishment of a biorefinery from this agro-industrial residue since its main compounds, cellulose, hemicellulose, and lignin, can be used to obtain several bioproducts. The influence of essential parameters was studied for the production of LA. The CABH contained mainly glucose and xylose at concentrations of approximately 40 g/L and 20 g/L, respectively. The process conducted at 30 °C, 100 rpm, and using the culture in the final of the growth phase (inoculum time of 24 h for LAB07 and 20 h for LAB14) and urea as nitrogen source enhanced the LA production for both strains, LAB07 and LAB14, reaching 24.3 g/L. The produced LA was used to synthesize polylactic acid (PLA) for the enzymatic route using lipase B from Candida antarctica (CALB). Then, the production of PLA from cashew apple bagasse hydrolysate is a sustainable alternative to produce a biodegradable polymer with many industrial applications and obtaining personal protective equipment to use in the current and future pandemics.

MICROBIOLOGICAL PROCESSES IN THE LUCERNE HAYLAGE UNDER INOCULATION WITH LACTIC ACID BACTERIA

Objective. To characterize the effect of lactic acid bacteria (LAB) on the quantitative and qualitative composition of the groups of microorganisms in the lucerne haylage after their introduction. Methods. Microbiological (cultivation of microorganisms on various media, determination of their viability, measurement of osmotolerance, determination of the amount of lactic acid during cultivation on skimmed sterile milk), microscopic, laboratory experiments on the lucerne haying with a dry matter (DM) content of 46 % and 37 % with and without inoculation with LAB strains, statistical. Results. Lucerne was inoculated with monocultures of Lactobacillus sp. LH42, Lactobacillus sp. LH43, Lactobacillus sp. LH47, L. plantarum КТ-L18/1 osmotolerant strains, which showed tolerance to 2 %, 4 %, 6.5 % sodium chloride in 100 % of cases. The best indicators in terms of active and titrated acidity were found in cultures of Lactobacillus sp. LН47, L. plantarum КТ-L18/1. The inoculation of LAB into the haylage ecosystem at Day 15 of fermentation resulted in an increase in the number of LAB compared to the untreated control. At Day 45 of lucerne haying, the number of LAB decreased and was registered at the level from 1 to 100 billion CFU/g at a 46 % DM content and at the level from 0.01 to 10 billion CFU/g at a 37 % DM content. The greatest development of clostridia in the lucerne haylage in experiments was reported at Day 3 with a sharp decrease in their number at Day 45. The influence of Lactobacillus sp. LH 43, Lactobacillus sp. LH 47, L. plantarum KT-L18/1 on the reduction of the growth of the number of clostridia both at a 46 % and 37 % DM content at the end of the fermentation period was shown. A higher number of yeasts was established at a lower (37 %) content of DM in the haylage. A fungistatic effect was established in variants with LAB inoculation versus the control variant. The relationship between the dynamics of decreasing active acidity (pH) and the dynamics of microbiota development has been shown. Conclusion. Inoculation of the studied strains of lactic acid bacteria into high-protein lucerne haylage mass contributed to an order of magnitude increase in the number of LAB versus the control variant, suppression of the development of clostridia, yeasts and a rapid decrease in active acidity, which confirms data about the effect of LAB-based inoculants on the fermentation of plant raw materials by adjusting the composition of groups of microorganisms

Selection and evaluation of lactic acid bacteria from chicken feces in Thailand as potential probiotics.

Lactic acid bacteria (LAB) are widely used as probiotics in poultry production due to their resilience to low pH and high bile salt concentrations, as well as their beneficial effects on growth performance and antagonistic activity against enteric pathogens. However, the efficacy of probiotics depends on strain selection and their ability to colonize the host's intestine. This study aimed to select, identify, and evaluate LAB strains isolated from chicken feces in Thailand for potential use as probiotics in the chicken industry. LAB strains were isolated from 58 pooled fresh fecal samples collected from chicken farms in various regions of Thailand, including commercial and backyard farms. Gram-positive rods or cocci with catalase-negative characteristics from colonies showing a clear zone on MRS agar supplemented with 0.5% CaCO3 were identified using MALDI-TOF mass spectrometry. The LAB isolates were evaluated for acid (pH 2.5 and pH 4.5) and bile salt (0.3% and 0.7%) tolerance. Additionally, their cell surface properties, resistance to phenol, antimicrobial activity, hemolytic activity, and presence of antimicrobial resistance genes were determined. A total of 91 LAB isolates belonging to the Pediococcus, Ligilactobacillus, Limosilactobacillus, and Lactobacillus genera were obtained from chicken feces samples. Backyard farm feces exhibited a greater LAB diversity compared to commercial chickens. Five strains, including Ligilactobacillus salivarius BF12 and Pediococcus acidilactici BF9, BF14, BYF20, and BYF26, were selected based on their high tolerance to acid, bile salts, and phenol. L. salivarius BF12 and P. acidilactici BF14 demonstrated strong adhesion ability. The five LAB isolates exhibited significant cell-cell interactions (auto-aggregation) and co-aggregation with Salmonella. All five LAB isolates showed varying degrees of antimicrobial activity against Salmonella strains, with P. acidilactici BYF20 displaying the highest activity. None of the LAB isolates exhibited beta-hemolytic activity. Whole genome analysis showed that L. salivarius BF12 contained ermC, tetL, and tetM, whereas P. acidilactici strains BF9 and BF14 carried ermB, lnuA, and tetM. The selected LAB isolates exhibited basic probiotic characteristics, although some limitations were observed in terms of adhesion ability and the presence of antibiotic resistance genes, requiring further investigation into their genetic location. Future studies will focus on developing a probiotic prototype encapsulation for application in the chicken industry, followed by in vivo evaluations of probiotic efficacy.

Short Communication: Diversity of indigenous LAB from kefir grains cultured in goat milk based on phenotypic characteristics for probiotic candidates

Abstract. Wulansari PD, Rahayu N, Kusuma RJ, Sukarno AS. 2023. Short Communication: Diversity of indigenous LAB from kefir grains cultured in goat milk based on phenotypic characteristics for probiotic candidates. Biodiversitas 24: 6389-6395. Kefir grain is the starter of kefir products containing the symbiotic compound of lactic acid bacteria (LAB) and yeast. Microbial diversity in kefir grain is affected by multiple factors that include the origin of microbiota, upkeep, storage, and types of milk. Goat milk exhibits various superior properties in composition or characteristics. These have inspired the present study to obtain the local isolates from LAB derived from native Indonesian kefir grain produced and revitalized using goat milk. This study aimed to obtain local LAB isolates from kefir grain through phenotypic identification and characterization. The morphology of phenotypic identification consisted of macroscopic, microscopic, and biochemical identification. Based on macroscopic and microscopic observation, the isolates were milky white, circular, entire edge, smooth and shiny surface with convex elevation, coccus/basil shaped, Gram-positive, negative catalase, non-motile, non-spore, non-producing CO2, heterofermentative/homofermentative, able to ferment various carbohydrates, growing at 37 and 45°C, pH 4.4, and salinity level of 6.5%. A scientific approach enabled to obtaining of several LAB strains, namely nine isolates of Lactococcus and seven isolates of Lactobacillus. It takes genotypic identification to promote the identification process up to the species level.

Soybean hull polysaccharides affect the physicochemical properties and lactic acid bacteria proliferation in plant‐based yogurt

AbstractAs a by‐product of soybean processing, soybean hulls contain soybean hull polysaccharides (SHPS). This study aims to develop a plant‐based yogurt with SHPS addition and assess the consequences of SHPS on the physicochemical properties and growth of lactic acid bacteria (LAB) in yogurts. The study investigated the water holding capacity (WHC), microstructure, rheological properties, texture, pH, organoleptic attributes, volatile compounds, flavor profile, and LAB population. The findings reveal that the addition of SHPS significantly impacted these properties. SHPS improved the physicochemical properties, increased the level of flavor compounds, and improved the organoleptic properties of yogurt. Yogurt with 0.6% SHPS demonstrated superior WHC, texture, rheological properties, and the highest organoleptic evaluation scores. However, when SHPS additions exceeded 0.6%, WHC, texture, and rheological properties of the yogurts decreased. Furthermore, SHPS‐added yogurts contained more LAB compared to yogurt without SHPS. LAB grew better in media with SHPS than in media without glucose. Streptococcus thermophilus grew best among the LAB strains. This study highlights the potential of SHPS in yogurt production and its promising applications in fermented food products.

Lactic Acid Bacteria isolated from traditional and innovative alheiras as potential biocontrol agents

From a selection of seven traditional and 14 innovative alheiras, 491 lactic acid bacteria (LAB) were isolated and tested for their antimicrobial activity against several food-borne pathogens. Among these, six strains revealed antimicrobial activity through potential bacteriocin production against 14 Listeria monocytogenes strains, Enterococcus faecalis ATCC 29212, Clostridium sporogenes ESB050, and Clostridium perfringens ESB054.Through whole genome sequencing (WGS), these strains were identified as Lactiplantibacillus plantarum (2), Leuconostoc mesenteroides (1), and Pediococcus acidilactici (3). Furthermore, several orthologues of class II bacteriocins genes were identified, including Plantaricin E, Plantaricin F, Pediocin PA, Enterocin X, Leucocin A, and Coagulin A. No virulence or antibiotic resistance genes’ orthologues were detected by WGS analysis. However, the selected LAB strains showed variable phenotypic patterns related to virulence genes and antibiotic resistance when assessed through classical methodologies. None of these strains demonstrated the production of biogenic amines, gelatinase or DNase. Additionally, no hemolytic activity or lipase enzyme production was observed. However, only Lpb. plantarum 9A3 was sensitive to all tested antibiotics and was thus chosen for further examination. The bacteriocins produced by Lpb. plantarum (9A3) exhibited stability across a broad range of conditions, including temperatures from 4 to 100 °C, pH values ranging from 2 to 8, exposure to surfactants and detergents (Tween 20 and 80, SDS, EDTA 0.1, 2 and 5 mM, urea and sodium deoxycholate), and enzymes (papain and catalase). Their maximum activity (AU/mL = 12,800) against four L. monocytogenes strains was observed between 21 and 36 h of growth of Lbp. plantarum 9A3, indicating a bacteriostatic mode of action. Therefore, this strain appears to be a robust candidate for potential application as a protective strain to be used in the food industry. Not only is it safe, but it also produces stable bacteriocins (harbouring genes encoding for the production of three) effectively inhibiting significant pathogens such as L. monocytogenes and C. perfringens.

Microbial network and fermentation modulation of Napier grass and sugarcane top silage in southern Africa.

Feed shortage in the tropics is a major constraint to the production of livestock products such as milk and meat. In order to effectively utilize of local feed resources, the selected lactic acid bacteria (LAB) strain was used to prepare Napier grass and sugarcane top silage. The results showed that the two silages inoculated with LAB formed a co-occurrence microbial network dominated by Lactiplantibacillus during the fermentation process, regulated the microbial community structure and metabolic pathways, and improved the silage fermentation quality. This is of great significance for alleviating feed shortage and promoting sustainable production of livestock.