Aims: Postbiotic metabolites are metabolic compounds produced by probiotic lactic acid bacteria. These compounds produced by Lactobacillus sp. have been shown to be effective substitutes for in-feed antibiotic in livestock due to their broad inhibitory activity. Therefore, the aim of this study was to determine the effects of various carbon and nitrogen sources on the bacteriocin-inhibitory activity of postbiotic metabolites produced by Lactobacillus plantarum I-UL4. Methodology and results: The effects of various combinations of carbon and nitrogen sources on the bacteriocininhibitory activity (expressed as modified bacteriocin activity, MAU/mL) of postbiotic metabolites produced by L. plantarum I-UL4 were determined in basal media without micronutrients. The combination of glucose (20 g/L) and yeast extract (22 g/L) gave the best bacteriocin-inhibitory activity as compared to other combinations. Maximum bacteriocininhibitory activity of 1440 MAU/mL was achieved when 36.20 g/L of yeast extract was added as the sole nitrogen source in modified de Man, Rogosa and Sharpe (MRS) medium. The glucose concentration was further optimised to enhance the bacteriocin-inhibitory activity of the postbiotic metabolites. Lower bacteriocin-inhibitory activity was observed at 5, 10, 15 and 40 g/L in comparison to 20 g/L of glucose. Conclusion, significance and impact of study: Maximum bacteriocin-inhibitory activity of postbiotic metabolites was achieved at 1440 MAU/mL when 20 g/L of glucose and 36.20 g/L of yeast extract were added as the sole carbon and nitrogen sources respectively in the modified MRS medium. Optimisation of other micronutrients present in MRS media is necessary to further enhance the bacteriocin-inhibitory activity of postbiotic metabolites produced by L. plantarum IUL4.
Lactobacillus

Aims: Lactobacillus sp. has capability of producing an array of bioactive metabolites that exhibit probiotic effects. Therefore, the objective of this study was to determine the cytotoxicity effect of proteinaceous postbiotic metabolites (PPM) produced by Lactobacillus plantarum I-UL4 cultivated in different media composition on MCF-7 breast cancer cell. Methodology and results: L. plantarum I-UL4 was cultivated in yeast extract and modified de Man, Rogosa and Sharpe broth containing Tween 80 (CRMRS+T80) or without Tween-80 (CRMRS-T80). Human breast adenocarcinoma cell (MCF-7) was employed as cancer cell in this study. Cytotoxicity and antiproliferative effects of PPM were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl Tetrazolium Bromide assay and Trypan Blue Dye Exclusion assay, whereas Acridine Orange/Propidium Iodide staining was employed to determine the cytotoxicity mechanism. PPM produced in CRMRS+T80 exerted cytotoxicity in a time and dose dependent manner that was selective towards MCF-7 cancer cell. Profound cytotoxicity with the lowest IC50 concentration of 10.83 µg was detected at 72 h of incubation, whereas the most potent antiproliferative effect revealed by the lowest viable cell population was observed at 24 h of incubation. PPM cultivated in CRMRS+T80 induced 80.87% of apoptotic MCF-7 cells at 48 h of incubation. Conclusion, significance and impact of study: PPM of L. plantarum I-UL4 cultivated in different media composition induced different levels of MCF-7 cancer cell death. The percentage of apoptotic MCF-7 cells treated with PPM cultivated in CRMRS+T80 increased significantly (p < 0.05) from 24 to 48 h of incubation. The results obtained in this study have revealed the potential of PPM produced by L. plantarum I-UL4 as human health supplement and as anticancer preventive agent. Keywords: Lactobacillus plantarum I-UL4; cytotoxic effect; proteinaceous postbiotic metabolites; media composition; breast cancer
Lactobacillus ; Probiotics

Aims: The specific aim of this study is to investigate the probiotic potentials of mucuna beans flour fermented with Lactobacillus acidophilus. Methodology and results: The L. acidophilus used was isolated from neonate faeces using the pour plate technique, thereafter, it was screened for growth and survival in the mucuna beans flour. Liquid fermentation method was adopted for fermentation of mucuna beans flour and at the end of 72 h fermentation at 37 °C, the L. acidophilus showed appreciable growth (90 × 105 CFU/mL). After storage for 14 days at refrigeration (4 ± 2 °C) and room temperature (25 ± 2 °C), there was a considerable increase in the Lactobacillus found in the products stored at room temperature (183.67 ± 3.28 ×105 CFU/mL) compared to the one stored at refrigeration temperature (94 ± 2.33 × 105 CFU/mL). There was a steady increase in the total titratable acidity and temperature with concomitant reduction in the pH of samples during the fermentation period. The proximate analysis showed that there was an increase in the protein and moisture contents with decrease in carbohydrates, fats, fiber and ash contents of the fermented samples compared to the unfermented sample. Under varying pH range, L. acidophilus showed high growth and survival at pH 2 to 3. Supplementing the diet of albino rats infected with E. coli and Shigella with fermented products reduces significantly (p ≤ 0.05) the numbers of these pathogens and other enteric bacteria while the number of the Lactobacilli increased considerably. Furthermore, the body weight of the rats fed the fermented product was significantly (p ≤ 0.05) higher than the control group. Also, the haematological analysis showed that the rats infected with the pathogens and later fed the fermented mucuna beans flour recovered fully since their values are well within the permissible limit and are not significantly (p ≤ 0.05) different from the control group. In all, the rats fed the product fermented with L. acidophilus showed good recovery compared to the control. Conclusion, significance and impact of study: The results of this investigation suggest that mucuna beans flour supports the growth and survival of L. acidophilus and exerts considerable probiotic effect on young mammals. Therefore, mucuna may be used as an ideal probiotic food.
Lactobacillus acidophilus ; Fermentation

Aims: In this study, lactic acid bacteria (LAB) were isolated from 42 healthy infants and determined for probiotic properties. Twelve LAB isolates with potential probiotic properties were selected and screened for their feasibility of heterologous protein expression by selection of erythromycin sensitive isolates. Methodology and results: One of eleven erythromycin-sensitive LAB isolates identified and designated as Lactobacillus fermentum 47-7 was able to acquire and stable maintain the Escherichia coli-Lactobacillus shuttle vector, pRCEID-LC13.9. Further electrotransformation of L. fermentum 47-7 with the recombinant pLC13.9:LDH-PRO1:GFPuv containing green fluorescent protein (GFP) gene found that recombinant L. fermentum can express GFP. Conclusion, significance and impact of study: The probiotic L. fermentum isolate can be used as host for expression of heterologous proteins and could possibly be further developed as the alternate oral delivery system for various biomolecules for biotechnological application.
Probiotic ; Lactobacillus fermentum

Aims: This study aimed to evaluate the effect of thermal treatment on the storage stability of Lactobacillus acidophilus La-14 tamarind juice with or without beta-glucans. Methodology and results: Lactobacillus acidophilus incorporated with 6% (w/v) beta-glucans displayed the highest viability (17.28 log10 CFU/mL) as compared to other beta-glucans concentrations (0-8% w/v). The L. acidophilus with or without beta-glucans survived more than 80% after 5 h of sequential digestion. Tamarind juice was subjected to different thermal treatments (76 °C for 30 sec or 90 °C for 60 sec) and incorporated with L. acidophilus with or without betaglucans. Lactobacillus acidophilus in tamarind juice without thermal treatment showed the highest viability (8.69 log10 CFU/mL), followed by thermal treatment at 76 °C for 30 sec (>7 log10 CFU/mL), and thermal treatment at 90 °C for 60 sec showed the lowest viability (>4 log10 CFU/mL), after 21 days at 4 °C. The pH, titratable acidity and viscosity of all L. acidophilus-tamarind juices demonstrated no changes throughout 21 days at 4 °C. Furthermore, thermal-treated tamarind juice (90 °C for 60 sec) incorporated with L. acidophilus displayed the least change in total soluble solids (1.99 °Brix), while thermal-treated tamarind juice (90 °C for 60 sec) with L. acidophilus and beta-glucans had the lowest color change (∆E = 4.46), after 21 days of storage at 4 °C. Conclusion, significance and impact of study Thermal treatments (90 °C for 60 sec) had contributed to the stability of L. acidophilus-tamarind juice with beta-glucans over 21 days of cold storage. This study shows thermal treated tamarind juice with L. acidophilus and beta-glucans is a potential functional non-dairy beverage catered for lactose intolerance individuals.
Lactobacillus acidophilus ; Food Microbiology

ABSTRACT Lactobacillus acidophilus (L. acidophilus) is one of the etiological agents for dental caries and dominant in the deep carious lesion. L. acidophilus has also been identified in persistent root canal infection and also related to the failure of endodontic treatment. Photodynamic therapy is a therapeutic process involving the combination of a nontoxic photosensitizer and a light source. The excited photosensitizer reacts with reactive oxygen species (ROS), which induce injury and death of the microorganism. This study aimed to prove the effect of irradiation time of photodynamic therapy to the number of L. acidophilus. Forty-two Eppendorf tubes were treated with 0.5 ml L. acidophilus distributed into seven groups. Group 1 as the control group received no treatment. Groups 2, 3, 4, 5, 6 and 7 were treated with a combination of 0.5 ml toluidine blue O (TBO) as a photosensitizer and 630 nm photoactivated (Fotosan®) exposure time for 10, 20, 30, 40, 50 and 60 sec. Then, all were stored in an incubator of 37ºC for 48 h. Later, the colony-forming unit (CFU) was counted for each group. There were significant differences in the number of L. acidophilus in CFU of the various irradiation times. The longer the photodynamic therapy irradiation was, the lesser the number of live L. acidophilus became. At 50 sec and 60 sec irradiation, none of the L. acidophilus was found alive.
Photochemotherapy ; Lactobacillus acidophilus

Aims: Probiotics are living microorganism, when administrated in sufficient quantity can exert beneficial effect to the host. This study focused on the microencapsulation by co-extrusion to increase the viability of Lactobacillus plantarum 299v (Lp299v) in gastrointestinal conditions, and its storage stability in kuini juice at refrigerated (4 °C) and ambient temperature (25 °C). Methodology and results: Lp99v was encapsulated with 1.5% w/v sodium alginate and chitosan coating (0.1% w/v) and yielded a microencapsulation efficiency of 97.71%. The Lp299v microbeads produced were spherical in shape and exhibited a mean microbeads size of 618.75 ± 25.85 µm. Acid and bile tolerance of both free and encapsulated Lp299v were tested in simulated gastric juice (SGJ) for 2 h and in simulated intestinal juice (SIJ) for 4 h, respectively. The encapsulated Lp299v maintained above 108 CFU/mL after exposure to artificial gastrointestinal juice, whereas a significant loss of viability was observed in the free cells. The storage stability of encapsulated Lp299v in kuini juice was determined during 4 weeks of storage at 4 °C and 25 °C. Results showed that encapsulated Lp299v was capable to remain viable (107 CFU/mL) for at least 4 weeks in a refrigerated condition. However, free Lp299v did not survived under both refrigerated and ambient temperature as the storage period extended. Conclusion, significance and impact of study Lp299v entrapped in chitosan-coated alginate microbeads produced by co-extrusion method is able to enhance the viability of Lp299v above the minimum recommended level in harsh environment (gastrointestinal conditions and low pH of kuini juice).
Cell Encapsulation ; Lactobacillus plantarum

In order to enrich the library of domestic research about new red fluorescent marker in lactic acid bacteria (LAB), we described a new fusion expression system in Lactobacillus plantarum WCFS1 based on the pSIP vector. This system contained red fluorescent protein mCherry as a marker and bile salt hydrolase gene (bsh) as a reporter gene. Moreover, in this study, four different promoters (PsppA, PldhL, P32 and PslpA) were used to regulate the expression of the fusion protein mCherry-BSH, completing the inducible and constitutive expression in lactic acid bacteria. The recombinant protein mCherry-BSH presented activity of red fluorescence and bile salt hydrolase (BSH). The successful construction of the fusion expression system in LAB using a red fluorescent protein mCherry provides favorable conditions for the distribution, intestinal colonization and survival rate of lactic acid bacteria, so as to reveal the function mechanism of its probiotic characteristics; and the system also could lay the foundation for researches on protein expression, cellular localization and properties identification of active protein in lactic acid bacteria.
Lactobacillus plantarum ; Luminescent Proteins ; Probiotics

OBJECTIVETo investigate the probiotic characteristics of Lactobacillus plantarum (L. plantarum) HO-69 in oral cavity.

METHODSThe adhesion ratios to teeth and dentine surface were determined by in vitro models. Hydrophobicity and surface charges were measured by MATH method. Inhibitory activity was measured by agar well diffusion method.

RESULTSThe adhesion ratios to hard tissue were quite low. The hydrophobicity and surface charges were high, and it exhibited inhibitory activity against some pathogens.

CONCLUSIONThe probability is low for L. plantarum HO-69 to initiate or accelerate dental caries. It shows broad-spectrum inhibitory activity and is potential probiotics applied in oral cavity.

Objectives: Probiotic supplementation often only leads to transient improvement in the gut microbiome. Potential prebiotics, such as the oligosaccharide-rich varieties of Dioscorea esculenta tubers, can potentially bridge the gap between supplementation and persistent colonization. Thus, this study aimed to assess the ability of D. esculenta tubers to promote the growth of probiotic Lactobacillus sp. in vitro selectively.

Methods: The prebiotic activity of the selected varieties of Dioscorea esculenta tubers was evaluated via compe titive growth assay, wherein the ratios of probiotic Lactobacillus sp. over enterotoxigenic Escherichia coli (ETEC) or "prebiotic ratios" were compared following treatment.

Results: Negative control (0.9% NaCl solution) produced a ratio of 0.88, Lowland and Highland varieties produced ratios of 1.26 and 1.29, respectively, and positive control (inulin) produced 1.54. The two varieties had comparable ratios to one another (p > 0.05), and significantly higher ratios than the negative control (p < 0.05). Both varieties have significant prebiotic activity. Compared to inulin, the two varieties' prebiotic activity was 84% as effective.

Conclusion: Overall, the tubers promoted the growth of Lactobacillus sp. over ETEC. The crude tuber samples, given their availability and affordability, can be easily integrated into the local diet to contribute to the improvement of the general population's health.