No abstract

No abstract

No abstract

No abstract

The most abundance of anti-Salmonella lactic acid bacteria (LAB) was found in feces of naturally born, exclusively breastfed Thai infants. Six strains of Lactobacillus plantarum and one strain of Lactobacillus paracasei were selected and identified. In the co-cultivation assay, L. plantarum subsp. plantarum I62 showed the strongest and broadest antibacterial activity against Escherichia coli, Shigella sonnei, Salmonella Paratyphi A, and Salmonella Typhimurium SA 2093 under the mimicked proximal colon condition, in which glucose and other nutrients were limited. According to GC-MS analysis, the major antibacterial contribution of organic acids secreted by L. plantarum I62 grown in the presence of glucose was dramatically reduced from 95.8 to 41.9 % under glucose-limited niche. The production of low-pK a acids, such as lactic, 1,2-benzenedicarboxylic, and 3-phenyllactic acids, was remarkably dropped. Surprisingly, higher-pK a acids such as 5-chlorobenzimidazole-2-carboxylic, pyroglutamic, palmitic, and oleic acids were enhanced. Moreover, cyclic dipeptides, ketones, alkanes, alcohols, and miscellaneous compounds, which were pH-independent antibacterial metabolites, became dominant. The electron microscopy strongly supported the synergistic attacks of the multiple antibacterial components targeting outer and cytoplasmic membranes leading to severe leakage and cell disruption of Salmonella Typhimurium. This strain poses to be a potential probiotic candidate for effectively controlling and treating human foodborne bacterial infection.

This study evaluated the effects of autochthonous starters on the quality characteristics of budu. The effects of individual or combined inoculation of Virgibacillus halodenitrificans PS21 and Staphylococcus simulans PMRS35 were compared to those of non-inoculation during 150 days of budu production. The starters directly affected characteristics of budu with browner colour and enhanced proteolysis and lipolysis as indicated by degree of hydrolysis and free fatty acid contents. The combined starter inoculation resulted in a high aspartic acid, glutamic acid and lysine levels. Additionally, key desirable volatiles, including 2-methylbutanal, 3-methylbutanal, benzaldehyde and 2-ethyl furan, were dominant in the starter-inoculated budu. In a sensorial analysis, the highest scores for appearance, colour, taste and flavour were assigned for inoculated budu with combined starters. Therefore, the addition of starters (V. halodenitrificans PS21 and S. simulans PMRS35) in budu production improved the quality characteristics and reduced the fermentation period.

From independent swab samples of the cloaca of indigenous gamecocks (CIG), anus of healthy baby goats (AHG), and vagina of goats (VG) originating from Phitsanulok, Thailand, a total of 263 isolates of lactic acid bacteria (LAB) were collected. Only three isolates, designated C707, G502, and V202, isolated from CIG, AHG, and VG, respectively, exhibited an excellent inhibitory zone diameter against foodborne pathogenic bacteria when evaluated by agar spot test. Isolates C707 and G502 were identified as Enterococcus faecium, whereas V202 was identified as Pediococcus acidilactici, based on 16S rRNA sequence analysis. When foodborne pathogenic bacteria were co-cultured with chosen LAB in mixed BHI-MRS broth at 39°C, their growth was suppressed. These LAB were found to be capable of surviving in simulated stomach conditions. Only the isolate G502 was able to survive in the conditions of simulated intestinal juice. This research suggests that selected LAB could be used as a food/feed supplement to reduce foodborne pathogenic bacteria and improve the safety of animal-based food or feed.

SummaryAspergillus flavus and Penicillium spp. are the most common spoilage fungi in the ready‐to‐eat, intermediate‐moisture Thai curry of Kaeng‐Tai‐Pla‐Haeng, which causes serious economic loss and public health concerns. The use of lactic acid bacteria (LAB) with antifungal activity has been a growing interest in food bio‐preservation. In this study, the antifungal efficacy of Lactiplantibacillus plantarum 124 (L. plantarum 124) against the spoilage fungi Aspergillus flavus and Penicillium sp. was evaluated. The cell‐free supernatants (CFSs) of L. plantarum 124 showed strong inhibition against A. flavus and Penicillium sp., with MIC ranging from 11.25 to 22.5 mg/mL. The significant loss of the antifungal activity was observed by pH neutralization, whereas either heat or proteinase K treatment showed no influence. The major compounds present in CFSs were lactic acid (49.57%) and acetic acid (25.85%). Others, such as 2,3‐dimethyl‐5‐ethylpyrazine (6.07%), 2,5‐dimethyl‐3‐propylpyrazine (2.10%), Cyclo(D‐Leu‐L‐Pro) (2.30%), Ethyl 5‐oxopyrrolidine‐3‐carboxylate (1.84%), and palmitic acid (1.80%) were detected at low relative amount. As observed by electron microscopy, the CFSs secreted by L. plantarum 124 caused severe damage to cell membranes, and organelles of A. flavus and Penicillium sp. In addition, L. plantarum 124 supernatant demonstrated no cytotoxicity on Vero cells and it could extend the food product's shelf‐life from 7 days to 21 days without any commercial preservatives. These results demonstrate that antifungal metabolites secreted by L. plantarum 124 are candidates for the development of bio‐preservative agents.