MRS Medium Research Articles

Molecular Diagnosis of Vaginal Microbiota Associated with Spontaneous Abortion in Women

Spontaneous abortion (SA) is a sever disease in which a women losses her foetus usually before 24 weeks of the pregnancy. About 10% -50% of pregnancy cases are run out with SA for reasons related with women's age and health. This condition occurrence may increases if the patient has a history of bacterial vaginosis. This study aimed at the characterization and isolation of vaginal microbiota generally and highlight on commensal bacteria becoming opportunistic when circumstances are favourable. From October to December 2022, about 100 samples were collected, 50 specimens from women with SA and 50 specimens from healthy pregnant outcomes (control). The high vaginal swabs samples were collected from Babylon Teaching Hospital for Maternity and Children and Imam Sadiq Teaching Hospital in Babylon, Iraq. To culture the samples, they were transported by media swab to laboratory. The culture of bacteria was done on 4 types of agar media: UTI chromogenic agar, MRS agar, MacConkey agar and blood agar. The first identification of bacteria was based on phenotypic traits of colonies, using manual biochemical tests and gram stain. Finally, the diagnosis was confirmed genetically by extracting bacterial genomic DNA for 20 of bacterial isolates under study and using PCR technique for 16S rRNA Loci gene and sequencing. The current study results showed difference in bacterial genera in women with SA compared with healthy women. It was also noted that embroilment of Enterococcus faecalis occurred in most cases of SA with an estimated percentage of 56% (28/50), thus defeating Escherichia coli by 32% (16/50) and 4% (2/50) for Klebsiella pneumonia and 4% (2/50) for Enterococcus gallinarum. In this study, some very rare bacteria species were identified including Acinetobacter junii at 2% (1/50) and Corynebacterium coyleae at 2% (1/50). While the percentage of bacteria associated with healthy women was: 30% (15/50) for E. faecalis, 26% (13/50) for E. coli, 18% (9/50) for K. pneumonia, 24% (12/50) for Staphylococcus epidermidis, and 2% (1/50) for Metabacillus niabensis (which was diagnosed for the first time in Iraq as well as the rest of the world in a clinical sample).

ISOLATION AND MOLECULAR IDENTIFICATION OF INDIGENOUS BACTERIOCIN-PRODUCING WEISSELLA CIBARIA

Globally, over 6.22 million deaths are associated with antibiotic resistance. Bacteriocins, a set of antimicrobial peptides synthesized on the ribosomes, are widely viewed as a potential answer to this issue. This is due to their pore-forming ability and antimicrobial activity against antibiotic-resistant pathogens. The aim of this study is to isolate bacteriocin-producing Weissella cibaria and evaluate its antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Salmonella typhi, Proteus mirabilis, Streptococcus sp., Candida sp. and Rhizopus stolonifer. Weissella cibaria man1 was isolated by inoculating deMan Rogosa Sharpe (MRS) broth with small pieces of ripe Mangifera indica (mango), 24-hour incubation at 370C, 10-fold serial dilution and plating on MRS agar. Molecular identification was achieved by DNA extraction, amplification of the 16S rRNA gene through polymerase chain reaction (PCR), agarose gel electrophoresis, gene sequencing, and BLASTN homology searches in the National Center for Biotechnology Information (NCBI). Antimicrobial activity of the bacteriocin was determined by agar well diffusion assay. Mangifera indica (mango) was found to harbor bacteriocin-producing Weissella cibaria man1. The bacteriocin (weissellicin man1) exhibited a broad spectrum of antimicrobial activity. Weissellicin man1 suppressed the growth of several target pathogens (Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Proteus mirabilis, Candida sp. and Rhizopus stolonifer) but had no inhibitory action against Escherichia coli, Streptococcus sp., Staphylococcus aureus. In conclusion, weissellicin man1 from Weissella cibaria man1 has a broad-spectrum of antimicrobial action. These findings will facilitate further evaluation of the antimicrobial potency of weissellicin man1.

Antineoplastic with DNA fragmentation assay and anti-oxidant, anti-inflammatory with gene expression activity of Lactobacillus plantarum isolated from local Egyptian milk products

Many lactic acid bacteria (LAB), known for their human health benefits, are derived from milk and utilized in biotherapeutic applications or for producing valuable nutraceuticals. However, the specific role of milk-associated LAB in biotherapeutics remains underexplored. To address this, eight milk product samples were randomly selected from the Egyptian market, diluted, and then cultured anaerobically on MRS agar. Subsequently, 16 suspected LAB isolates were recovered and underwent rapid preliminary identification. Among these isolates, the Lactobacillus plantarum strain with accession number (OQ547261.1) was identified due to its strong antioxidant activity depending on the DPPH assay, L. plantarum displayed notable antioxidant activities of 71.8% and 93.8% at concentrations of 125–1000 µg/mL, respectively. While ascorbic acid showed lower concentrations of 7.81, 3.9, and 1.95 µg/mL which showed activities of 45.1%, 34.2%, and 27.2%, respectively. The anti-inflammatory efficacy of L. plantarum was evaluated based on its capability to prevent hemolysis induced by hypotonic conditions. At a concentration of 1000 µg/mL, L. plantarum could reduce hemolysis by 97.7%, nearly matching the 99.5% inhibition rate achieved by the standard drug, indomethacin, at an identical concentration. Moreover, L. plantarum exhibited high hemolytic activity at 100 µg/mL (14.3%), which decreased to 1.4% at 1000 µg/mL. The abundance of phenolic acids and flavonoids was determined by high-performance liquid chromatography (HPLC) in L. plantarum. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) demonstrated that L. plantarum increased gene expression of the inflammatory marker TLR2 by 133%, and cellular oxidation markers SOD1 and SOD2 by 65% and 74.2%, respectively, while suppressing CRP expression by 33.3%. These results underscore L. plantarum’s exceptional anti-inflammatory and antioxidant activities. Furthermore, L. plantarum induces cancer cell death through necrotic nuclear DNA fragmentation. These findings suggest that L. plantarum is not only suitable for nutraceutical production but also holds potential as a probiotic strain. Future research should focus on enhancing the capacity of this strain across various industries and fostering innovation in multiple fields.

Reusable Immobilized Lactobacillus futsaii CS3 for Enhanced GABA Synthesis using Low-Cost Substrates in Fermenter-Scale Batch and Fed-Batch Fermentations

On the industrial scale, the cost of commercial culture media for the production of gamma-aminobutyric acid (GABA) is a very important factor. This study employed a low-cost substrates and by-product from agri-food industry for GABA synthesis by Lact. futsaii CS3 at the fermenter-scale. Lact. futsaii CS3 cells were immobilized in 3 % (w/v) sodium alginate and employed for GABA synthesis in the optimal modified MRS medium (3.48 % (w/v) cane sugar, 3.84 % (w/v) tuna condensate waste and 10.77 % (w/v) monosodium glutamate (MSG)) with the initial pH medium of 5, fermentation temperature at 37 °C and agitation speed at 30 rpm. During the 60th h of batch fermentation without pH control, immobilized Lact. futsaii CS3 efficiently transformed MSG into the highest GABA of 19.05 g/L, achieving the volumetric productivity of 0.32 g/L/h with a bioconversion rate of 29.01 %. To further enhance GABA production, MSG (7.5 % w/v) was fed into the fermenter during the 48th h of fed-batch fermentation, aiming to amplify GABA synthesis. The maximum GABA (26.28 g/L) was synthesized at 84 h of fed-batch fermentation, and the volumetric productivity and a bioconversion rate of 0.31 g/L/h and 23.59 %, respectively, were obtained. Fed-batch fermentation significantly outperformed batch fermentation, resulting in a 37.95 % increase in GABA production. Moreover, immobilized Lact. futsaii CS3 cells could be reused in 2 batch cycles. In the 1st reusability, the maximum GABA synthesis reached 25.94 g/L, and the volumetric productivity and a bioconversion rate of 0.31 g/L/h and 23.29 %, respectively, were achieved at 84 h of fed-batch fermentation. While in the 2nd reusability, GABA synthesis decreased to 23.29 g/L, with the volumetric productivity and a bioconversion rate of 0.28 g/L/h and 20.91 %, respectively, at 84 h of fed-batch fermentation. HIGHLIGHTS GABA production utilizing agri-food industry by-product. GABA production was enhanced by cane sugar and tuna condensate waste. Immobilized futsaii CS3 produced GABA 19.05 g/L (batch). Immobilized futsaii CS3 produced GABA 26.28 g/L (fed-batch). Immobilized futsaii CS3 could be reused in 2 batch cycles on GABA production. GRAPHICAL ABSTRACT

Probiotic and fermentation properties of Leuconostoc mesenteroides strain I1/53 from sugarcane juice by a multi-omics approach

Previous studies have demonstrated the presence of microorganisms in sugarcane juice, but the species composition and characteristics of dominant strains remain ambiguous. In this study, the most abundant strain Leuconostoc mesenteroides accounted for 39.89% of the total sequences in sugarcane juice. Subsequently, a L. mesenteroides, here named as strain I1/53, was isolated on a typical MRS medium. The whole genome size of the isolate was 2,044,872 bp with a GC content of 37.5% and 2027 coding DNA sequences with average length of 907 bp. Notably, the strain involved no antibiotic-related and virulence factor-producing genes, not producing endotoxins. In contrast, the L. mesenteroides I1/53 contained abundant adaptability and stress tolerance response genes of the human gastrointestinal environment. Additionally, strain I1/53 potentially encoded bacteriocin lactococcin G by expressing lagD, and demonstrated its antibacterial efficacy against Gram-positive and negative foodborne pathogens by in-vitro experiments. The fermentation of the strain I1/53 significantly elevated beneficial metabolites such as SCFAs, liquiritigenin, L-catechin, α-solanine and indoleacetic acid, whereas deleted harmful compounds for human wellness, including valdecoxib. Therefore, this study demonstrates the probiotic and fermentation properties of the dominant L. mesenteroides in sugarcane juice, which provide a robust theoretical foundation for its application in foods as a probiotic.

Production of Magnesium Dilactate through Lactic Acid Fermentation with Magnesium Carbonate.

Magnesium dilactate is increasingly sought after for its applications in the pharmaceutical, food, and dietary supplement industries due to its essential role in various physiological processes. This study explores a sustainable method for synthesizing magnesium dilactate through lactic acid fermentation using tomato juice, coupling the neutralization of lactic acid with hydrated magnesium carbonate hydroxide. Utilizing the lactic acid bacteria Lactobacillus paracasei and Lactobacillus plantarum, fermentation was optimized in a 50% diluted MRS medium supplemented with glucose and tomato juice supplemented with glucose, yielding a maximum lactate concentration of 107 g/L. Notably, fermentation in diluted media proved more effective than in undiluted tomato juice, highlighting the inhibitory effects of certain organic compounds and the physical nature of the original tomato juice. Post-fermentation, magnesium lactate was crystallized, achieving high recovery rates of up to 95.9%. Characterization of the product through X-ray diffraction and scanning electron microscopy confirmed its crystalline purity. This research underscores the viability of tomato juice as a fermentation substrate, promoting the valorization of agricultural by-products while providing an eco-friendly alternative to traditional chemical synthesis methods for magnesium dilactate production.

Effects of different processing methods on physicochemical and microbiological properties of kefir ice cream

In this study, kefir ice cream was produced using two different methods. In method 1, the ice cream mixture was incubated with kefir starter culture until a pH value of 6.1 or 5.5 was reached, and in method 2, the ice cream mixture was blended with kefir to reach a pH value of 5.5 or 6.1. Kefir ice cream produced by method 2 had a higher overrun and lower firmness than that produced by method 1. When comparisons were made based on the pH value of the ice cream mixture, kefir ice cream produced from the ice cream mixture with a pH of 6.1 instead of 5.5 had a higher overrun and melting rate and a lower firmness. The slightly higher counts on MRS agar, M17 agar, MSE agar, DSM 254 medium, and YGC agar were determined in the kefir ice cream samples produced by method 1 or produced from an ice cream mixture with a pH of 5.5. Although it is unknown if the number of bacteria on MRS agar detected in the samples, where the number was greater than 6 log cfu g−1 even after 90 days of storage, are probiotics or not, kefir ice cream has the potential to be a probiotic product. In this study, it has been demonstrated that kefir ice creams with different physicochemical and microbiological properties can be produced by altering the ice cream production method and pH value of the ice cream mixture.

Different Combinations of Nitrogen and Carbon Sources Influence the Growth and Postbiotic Metabolite Characteristics of Lactiplantibacillus plantarum Strains Isolated from Malaysian Foods.

Postbiotic metabolites produced by Lactiplantibacillus plantarum strains isolated from Malaysian food have been extensively reported for their positive effects on health. Understanding the effects of different combinations of carbon and nitrogen sources on the growth and corresponding characteristics of postbiotic metabolites produced by different strains of L. plantarum is important for various applications. Hence, the effects of different combinations of carbon (glucose, lactose, sucrose and dextrose) and nitrogen (X-SEED Kat, X-SEED Peptone, X-SEED Nucleo Advanced, Nucel875 MG, FM888 and FM902) sources on the growth of six strains of L. plantarum (RG11, RG14, RI11, RS5, TL1 and UL4) and the functional characteristics (bacteriocin inhibitory activity, antioxidant activity and lactic acid concentration) of their respective postbiotic metabolites were investigated in this study. UL4 produced the highest viable cell population with sucrose and Nucel875 nitrogen source. The UL4 strain also produced the strongest bacteriocin inhibitory activity with dextrose and FM888 nitrogen source. In comparison, the RI11 strain produced the highest lactic acid concentration with dextrose and Nucel875 nitrogen source and the highest reducing power of RS5 and TL1 postbiotic metabolites was achieved with MRS medium. In the combination of sucrose and X-Seed KAT nitrogen source, RG14 produce the highest hydroxyl radical scavenging activity. The effects of different combinations of carbon and nitrogen sources on the viable cell population of L. plantarum strains and the respective functional characteristics of postbiotic metabolites were strain dependent. The current study also revealed that fermentation media were an important factor that greatly impacted the functionalities of postbiotic metabolites due to the presence of various bioactive compounds that contributed to high antioxidant and antimicrobial properties. The results of this study will facilitate the subsequent medium design and optimisation for the development and production of specific postbiotic metabolites produced by the respective L. plantarum strain for their applications in various industries.

Fermentation dynamics of bile salt hydrolase production in Heyndrickxia coagulans ATCC 7050 and Lactiplantibacillus plantarum ATCC 10012: Addressing ninhydrin assay limitations with a novel HPTLC–MS method

Bile salt hydrolase (BSH), a pivotal enzyme in cholesterol management, holds significant promise in both human and animal subjects. This study investigated the effect of fermentation dynamics in Heyndrickxia coagulans ATCC 7050 and Lactiplantibacillus plantarum ATCC 10012 to enhance BSH production. Cultivation of cultures in MRS and M17 media revealed that MRS medium enhanced BSH production by 235.98 % in H. coagulans ATCC 7050 and 147.37 % in L. plantarum ATCC 10012, compared to M 17 medium. Additionally, varying oxygen concentration levels indicated that H. coagulans ATCC 7050 exhibited its minimum doubling time of 79.8 ± 0.64 min in anaerobic conditions, whereas L.plantarum ATCC 10012 demonstrated its minimum doubling time of 85.5 ± 1.2 min under microaerophilic conditions. However, their highest BSH activity was observed during the stationary phase under anaerobic conditions, yielding 17.14 ± 0.78 U/mL by H. coagulans ATCC 7050 and 19.04 ± 0.81 U/mL by L.plantarum ATCC 10012. Furthermore, it was observed that both organisms did not retain BSH within their cells. BSH activity was assessed using ninhydrin assay that detected free taurine liberated from sodium taurocholate. However, ninhydrin can yield false–positive results owing to its interaction with other free amino acids. To subjugate this limitation, the study introduced a novel and sensitive HPTLC–MS method capable of accurately detecting taurine. By comprehending fermentation dynamics and selecting appropriate conditions, BSH production increased 2.1–fold in both organisms. These findings illuminate critical insights, offering a pathway for novel strategies to enhance the BSH–producing capabilities of these LAB strains.

Unlocking the Potential of Lactococcus lactis subsp. lactis BIONCL17752 strain on Fumonisin B1 production by Fusarium verticillioides

Mycotoxins are the potent toxic chemical agent's linked to food safety, pose a serious risk to human and animal health globally. The management of toxigenic fungi is a challenging task in food and feed industries. The present investigation aimed to use probiotic potentials of lactic acid bacteria (LAB), and fermented cell-free broth as antifungal agents and neutralization of carcinogenic mycotoxin, fumonisin B1 (FB1) in food and feed considered as “turned waste into treasure”. We strived to investigate the probiotic potential of Lactococcus lactis subsp. lactis BIONCL17752 strain on prevention of growth and neutralization of FB1 produced by Fusarium verticillioides BIONCL4 strain to emulate as as a food grade bio-preservative. The BIONCL17752 strain exhibited excellent inhibitory activity against BIONCL4 strain. It was cultivated in MRS medium, and obtained cells pellet (CP) and cell-free supernatant (CFS) was lyophilized, and used for their antifungal activity against BIONCL4 strain. The minimum fungicidal concentration (MFC) determined as 12.5 μg/mL. Nevertheless, CFS assessed for neutralization of FB1 production which exhibited complete inhibition and downregulation of FB1 encoding FUM1 gene expression using quantitative real-time PCR (qPCR). Furthermore, CFS induced transcriptomic studies against BIONCL4 strain endorsed a significant downregulation of virulence, FB1, fusaric acid, fusarin, and chitin biosynthetic pathway genes. The CFS and cells reticent spore germination and FB1 production in the range of 40–61% and 74–85%, respectively under stored maize for 60 days. The current findings suggest BIONCL17752 strain apprehend the fungal growth and inhibit the FB1, and other toxigenic molecules biosynthesis, and can be employed as food grade preservative in the food industries to ensure the food safety and human health.

Development a modified MRS medium for enhanced growth of psychrotrophic lactic acid bacteria isolated from kimchi

When culturing psychrotrophic lactic acid bacteria (LAB) isolated from kimchi, the commonly used de Man, Rogosa and Sharpe (MRS) medium does not sufficiently satisfy the nutritional requirements for all bacteria. To overcome this limitation, a modified MRS medium (m-MRS) and culture conditions tailored for psychrotrophic LAB were developed via statistical optimization using response surface methodology (RSM) and partial least squares–genetic algorithm (PLS–GA). A one–factor method based on the MRS medium was used to determine the medium composition. Glucose, sucrose, and mannose (6.7 g/L each) were selected as carbon sources, and soy peptone (19.11 g/L), a plant-based alternative, was used as a nitrogen source, replacing beef extract. Tomato juice (1 g/L) and L-ascorbic acid (0.1 g/L) were selected as growth factors. These factors were treated as independent variables and optimized using RSM, and PLS–GA. Temperature, incubation time, and pH were utilized as independent variables for RSM and PLS-GA to optimize the culture conditions. Compared to the MRS medium, the m-MRS broth provided better support for the growth of most psychrotrophic LAB strains tested. Thus, m-MRS medium and optimized conditions can be effectively applied to culture psychrotrophic LAB isolated from kimchi.

Probiotic Properties of Lactobacilluscasei and L. plantarum Isolated From Overripe Avocado Pear

Probiotics have been researched for their benefit to gut health. Research for sources of probiotic bacteria has moved from milk to plants, as they have been found to be an inexhaustible source of lactic acid bacteria (LAB). The probiotic properties of lactic acid bacteria isolated from Over ripe Avocado pear on selected bacterial species were assessed. Fifty Unripe Avocado pears were purchased from different markets and allowed to ferment. Enumeration of the microorganisms and pure culture isolation were done on MRS agar supplemented with1.0% CaCO3 at 37 oC for 48 hours; using the pour plate and streak plate methods respectively. The isolates were identified based on their microscopic, macroscopic, biochemical and molecular characteristics. They include Lactobacillus casei and L. plantarum. LAB isolates were tested for their phenol tolerance, bile salt tolerance, acid tolerance and antimicrobial activity. All the isolates were tolerant to simulated gastrointestinal conditions. Growth of the isolates was observed at different temperature between 15 oC to 60 oC. They exhibited tolerance to phenol ranging from 0.085±0.01% to 2.40±0.02%. Tolerance to bile salt ranged from 1.06x101± 0.96x101 to 3.04x103±1.15x102. The acid tolerance level of the LAB obtained ranged from 2.98x102±1.30x102 to 8.78x102±2.22x102. Agar-well diffusion method was used to determine the antimicrobial susceptibility of the bacterial species. The test showed that the isolates were susceptible to the LAB isolates as zones of inhibition were observed. The inhibition zones diameter obtained ranged from 8.35±1.34mm to 13.77±2.21mm. Avocado pear, asides from their high nutritional content, also have the potential to serve as source of probiotic bacteria.

Exopolysaccharide (EPS) Produced by Leuconostoc mesenteroides SJC113: Characterization of Functional and Technological Properties and Application in Fat-Free Cheese

A Leuconostoc mesenteroides strain (SJC113) isolated from cheese curd was found to produce large amounts of a mucoid exopolysaccharide (EPS). An analysis revealed the glucan nature of the EPS with 84.5% (1→6)-linked α-d-glucose units and 5.6% (1,3→6)-linked α-d-glucose units as branching points. The EPS showed 52% dextranase resistance and a yield of 7.4 ± 0.9 g/L from MRS medium supplemented with 10% sucrose within 48 h. Ln. mesenteroides SJC113 was also characterized and tested for the production of EPS as a fat substitute in fresh cheese. Strain SJC113 showed high tolerance to a wide range of NaCl concentrations (2, 5 and 10%), high β-galactosidase activity (2368 ± 24 Miller units), cholesterol-reducing ability (14.8 ± 4.1%), free radical scavenging activity (11.7 ± 0.7%) and hydroxyl scavenging activity (15.7 ± 0.4%). The strain had no virulence genes and was sensitive to clinically important antibiotics such as ampicillin, tetracycline and chloramphenicol. Ln. mesenteroides SJC113 produced highly viscous EPS during storage at 8 °C in skim milk with 5% sucrose. Therefore, these conditions were used for EPS production in skim milk before incorporation into fresh cheese. Four types of fresh cheese were produced: full-fat cheese (FF) made from pasteurized whole milk, non-fat cheese (NF) made from pasteurized skim milk, non-fat cheese made from skim milk fermented with Ln. mesenteroides without added sugar (NFLn0) and non-fat cheese made from skim milk fermented with Ln. mesenteroides with 5% sucrose (NFLn5). While the NF cheeses had the highest viscosity and hardness, the NFLn5 cheeses showed lower firmness and viscosity, higher water-holding capacity and lower weight loss during storage. Overall, the NFLn5 cheeses had similar rheological properties to full-fat cheeses with a low degree of syneresis. It was thus shown that the glucan-type EPS produced by Ln. mesenteroides SJC113 can successfully replace fat without altering the texture of fresh cheese.

Oxygen Transfer Effect on the Growth of Limosilactobacillus reuteri ATCC 53608 and on Its Metabolic Capacity

Limosilactobacillus reuteri is a probiotic microorganism used in the treatment of gastrointestinal disorders. The effect of oxygen transfer on cultures of L. reuteri ATCC 53608 at shake flask and stirred tank bioreactor scales was studied, using MRS and molasses-based media. At shake flask scale, in MRS medium, a maximum bacterial concentration of 2.01 ± 0.02 g L−1 was obtained; the oxygen transfer coefficient was 2.01 ± 0.04 h−1. Similarly, in a 7.5 L bioreactor, in MRS, a maximum bacterial concentration of 2.46 ± 0.16 g L−1 was achieved (kLa = 2.64 ± 0.06 h−1). In contrast, using a molasses-based medium, bacterial concentration reached 3.13 ± 0.17 g L−1 in the 7.5 L bioreactor. A progressive reduction in lactic acid concentration and yield was observed as the oxygen transfer coefficient increased, at shake flask scale. Also, the oxygen transfer coefficient strongly affected the growth of L. reuteri in shake flask and bioreactor and allowed us to successfully scale up L. reuteri culture, producing similar maximum bacterial concentrations in both scales (2.01 g L−1 and 2.46 g L−1 in MRS). This is the first study on oxygen transfer coefficients in L. reuteri, and it is a valuable contribution to the field as it provides important insights about how this organism tolerates oxygen and adapts its metabolism for larger biomass production.Graphical

Bacteriocin paracin wx3 biosynthesis improves antagonistic activity of Lactobacillus paracasei WX322 against soft rot of postharvest pepper

Postharvest peppers are susceptible to soft rot caused by Pectobacterium carotovorum during storage and transportation. Lactic acid bacteria (LAB) are promising antagonist to control soft rot. LAB usually exhibit strong in vitro antibacterial activity on MRS agar plates, but weak in vivo disease control activity on fruit/vegetable. This study aimed to improve the biocontrol activity of Lactobacillus paracasei WX322 in vivo. Stress conditions were firstly investigated and the results showed that starvation stress could not induce any enhancement of antibacterial activity in vitro. Acid-base stress only improved antibacterial activity in vitro, while osmotic stress under 1.5 % NaCl improved both antibacterial activity in vitro and disease control activity in vivo. To facilitate the adaptation of L. paracasei WX322 on green pepper, pepper juice was used to replace MRS medium. To facilitate the growth of L. paracasei WX322 in pepper juice, nutrient supplement was studied. The result showed that pepper juice containing 0.4 % Tween 80 and 1.5 % NaCl was the optimal induction condition which improved the antagonistic activity of L. paracasei WX322 by enhancing LAB’s metabolism. Bacteriocin production was significantly improved under the optimal induction condition. The result of RT-qPCR revealed that bacteriocin production related genes were significantly up-regulated under the optimal induction condition, including three-component system. The addition of 1 μM autoinducer peptide (AIP) in MRS significantly increased antibacterial activity of L. paracasei WX322 in vitro. Simultaneously, L. paracasei WX322 cultured in MRS containing 0.01 μM AIP had a significantly increased disease control activity. RT-qPCR further verified an increased expression of bacteriocin paracin wx3 when adding 0.01 μM AIP. These results suggest that the medium of pepper juice containing 0.4 % Tween 80 and 1.5 % NaCl can improve the in vivo disease control activity of L. paracasei WX322, which is achieved by improved bacteriocin biosynthesis regulated by three-component system.

A Novel Bioprotective Strain of Lactiplantibacillus plantarumF2-Physiological, Genetical, and Antimicrobial Characterization.

Lactiplantibacillus plantarum is a member of lactic acid bacteria that improves the quality of fermented foods while also having a positive impact on human health. In this study, L. plantarum F2 was studied for characteristics such as biochemical and genetic identification, metabolite production, antimicrobial activity, and plasmid content. This strain exerts antimicrobial activity against some Gram-positive and Gram-negative pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli) with inhibition zone diameters ranging between 17.0 and 29.0 mm; it can ferment glucose, arabinose, galactose, lactose, and demonstrated the ability to grow at high temperature (50°C). Another physiological specification of the strain was the morphology of the isolate in selective medium, the de Man, Rogosa, Sharpe medium (MRS medium containing triphenyl tetrazolium chloride), which exhibits a chromogenic colony (characterized as purple colonies) on the modified-MRS (mMRS) medium. Metabolites such as lactic acid and diacetyl production of the strain F2 were also investigated using chromatography and found to be 10.07 and 0.05 µg/mL, respectively. The peptides of the isolate's cell-free supernatant were determined to be ∼80 kDa, and finally, the plasmid isolated from the strain F2 was identified as L. plantarum strain KLDS1.0386 plasmid p4, which may be responsible for some characteristic properties, such as antimicrobial peptide production of the strain.

Exopolysaccharides from Weissella cibaria isolated from oats: isolation, characterisation and its application in improving the texture of set‐type yogurt

SummaryIn this study, a lactic acid bacteria strain isolated from oats was used as a producer to obtain exopolysaccharide (EPS) using MRS agar plates. The findings indicated that the bacterial strain identified as Weissella cibaria (accession number: PP515290) was shown to have good probiotic activity, adapt better to alkaline than acidic conditions, and efficiently produce EPS at concentrations of up to 7.93 g L−1. SEM images showed a smooth surface and compact particle whereas FTIR confirmed the basic functional groups of polysaccharides in the sample. Meanwhile, XRD analysis demonstrated a non‐crystalline amorphous structure and thermal analysis indicated two‐phase thermal decomposition with maximum rate at 210 °C. Subsequently, EPS from W. cibaria was applied as stabiliser in set‐type yogurt (ex situ) in comparison with yogurt using mixed culture with W. cibaria (in situ) and traditional starter culture (control). The results showed that the addition of 2% EPS significantly improved syneresis (14.31%) compared to co‐culture (27.50%) and control (29.80%) as well as increased hardness of yogurt during 2‐week refrigeration.

A high-throughput spectroscopic method for pH determination in lactic acid bacteria screening

In this study, a colorimetric method was developed to enable the rapid determination of lactic acid bacteria (LAB) acidification ability by assessing the pH drop during juice fermentation. The proposed method used spectrophotometry to track pH variations induced by LAB, utilizing bromophenol blue as a pH indicator. This colorimetric method demonstrated linearity within the pH range of 2.50–5.70. Optimal performance was achieved with 5.0 % bromophenol blue, yielding a linear equation of y = 1.25x-0.78, with an R2 value of 0.99 upon regression analysis. The method's high accuracy, repeatability and reproducibility were validated through comparisons of pH values obtained using different matrices with those measured using glass electrodes/pH meters. Several Lactiplantibacillus plantarum strains with excellent acid-producing properties were identified through this method. Specifically, the growth of L20, L2 and L6 in MRS medium with a glucose concentration of 200 g/L for 24 h led to a pH decrease of 1.00 unit, while the growth of L20 and L21 in MRS with an ethanol concentration of 12 % (v/v) for 24 h resulted in a similar pH decrease. Strains L12, L14, and L18 could lower the pH of banana and lychee juices by more than 0.30 units at both 25 and 36°C. These results highlight the effectiveness of the method for rapidly screening LAB acidifying activity.

Integrating fruit by-products and whey for the design of folate-bioenriched innovative fermented beverages safe for human consumption

Global concerns over folate deficiency, the risks of excessive synthetic folic acid consumption, and food loss implications for environmental sustainability and food security drive needs of innovative approaches that align food by-product valorisation with folate bio-enrichment. This study explored the use of three fruit by-products extracts (grape, passion fruit, and pitaya) and whey to develop a folate bio-enriched fermented whey-based beverage. Three strains (Lacticaseibacillus rhamnosus LGG, Bifidobacterium infantis BB-02, and Streptococcus thermophilus TH-4) were tested for folate production in different fermentation conditions in modified MRS medium and in a whey-based matrix prepared with water extracts of these fruit by-products. B. infantis BB-02 and S. thermophilus TH-4, alone and in co-culture, were the best folate producers. The selection of cultivation conditions, including the presence of different substrates and pH, with grape by-product water extract demonstrating the most substantial effect on folate production among the tested extracts, was crucial for successfully producing a biofortified fermented whey-based beverage (FWBB). The resulting FWBB provided 40.7 μg of folate per 100 mL after 24 h of fermentation at 37 °C, effectively leveraging food by-products. Moreover, the beverage showed no cytotoxicity in mouse fibroblast cells tests. This study highlights the potential for valorising fruit by-products and whey for the design of novel bioenriched foods, promoting health benefits and contributing to reduced environmental impact from improper disposal.

Molecular identification of lactic acid bacteria from traditional fermented foods and screening exopolysaccharide production by using food wastes.

In this study, lactic acid bacteria (LAB) isolation from fermented foods and molecular identification using magnetic bead technology were performed. And then exopolysaccharide (EPS) production possibility was tested in agar medium, and the positive ones were selected for the next step. The bacteria that could produce higher carbohydrate level were grown in MRS medium fortified with whey and pumpkin waste. In our study, 19 different LAB species were identified from fermented products collected from different places in Hatay(Türkiye) province. In molecular identification, universal primer pairs, p806R/p8FPL, and PEU7/DG74 were used for PCR amplification. After that, PCR products purified using paramagnetic bead technology were sequenced by the Sanger sequencing method. The dominant species, 23.8% of the isolates, were identified as Lactiplantibacillus plantarum. As a technological property of LAB, exopolysaccharide production capability of forty-two LAB isolate was tested in agar medium, and after eleven isolates were selected as positive. Two LAB (Latilactobacillus curvatus SHA2-3B and Loigolactobacillus coryniformis SHA6-3B) had higher EPS production capability when they were grown in MRS broth fortified with pumpkin waste and whey. The highest EPS content (1750mg/L glucose equivalent) was determined in Loigolactobacillus coryniformis SHA6-3B grown in MRS broth fortified with 10% pumpkin waste. Besides the produced EPS samples were validated with FTIR and SEM methods.