lactobacillus heat tolerance

139, 1973–1978. Food Cont. Profiles of the biochemical reactions were recorded visually, and identifications obtained using the API software (BioMerieux). Differentiation of Lactobacillus sanfranciscensis strains by randomly amplified polymorphic DNA and pulsed-field gel electrophoresis. 69, 6801–6807. Cells from 1 ml MRS broth (Oxoid) culture were harvested by spinning at 9,000 g for 2 min, 4°C and suspended in 1 ml of maximum recovery diluent (MRD, Oxoid). 17, 190–198. Mugampoza, D. (2013). Salt tolerance was examined under the same conditions by inoculating the isolates into MRS broth containing 3.5, 5, 8, and 10% sodium chloride (Fisher Scientific, United Kingdom). There is a need for further studies to assign all Lactobacillus isolates to their subspecies. Bacterial community dynamics during production of registered designation of origin salers cheese as evaluated by 16S rRNA gene single-strand conformation polymorphism analysis. However, despite the high prevalence of the gene among the isolates from the outer crust, none of these lactobacilli showed activity in the CFS, implying failure to express the genes. Further 10-fold dilutions up to 10–9 were prepared in MRD.

Hiscox, E. R., Harrison, J., and Wolf, J. (2009). <> For each isolate, a colony was inoculated in 10 ml MRS broth (Oxoid) and incubated for 16 h at 30°C. Ares-Yebra, A., Garabal, J. I., Carballo, J., and Centeno, J. A strain of Lactobacillus ferm… 30, 8–13. Dairy J. This would allow evaluation of nutrients as a potential risk factor for persistence and subsequent colonization of Lactobacillus in the cheese production environment which is the most likely source of cross-contamination onto the outer crust. The vials were fully immersed in a water bath (Grant Instruments, Royston, United Kingdom) pre-heated to 72 ± 1°C, and 0.1 ml samples withdrawn at different time points into pre-cooled (4°C) MRD (Oxoid). The broths were incubated at 30°C and 100 rev min–1 in a shaking incubator (Gallenkamp, Loughborough, United Kingdom). Dairy Sci. endstream A. 2020-10-28T02:34:44-07:00 L. plantarum strains R22, R23, and R37 exerted no activity against S. aureus. This was the case for L. plantarum strains B30, W13 and W30. Diversity, dynamics, and activity of bacterial communities during production of an artisanal Sicilian cheese as evaluated by 16S rRNA analysis.

Salt tolerance of L. plantarum isolates from Stilton cheese: (A) R2, outer crust; (B) B14, blue veins; (C) W30, white core. Although LABs have been associated with potential health advantages, they are also responsible for negative outcomes.

All clusters (except II and IV) had related PFGE profiles and only contained isolates from the blue veins and white core implying clonal relationship. Bile salt and acid tolerance of Lactobacillus rhamnosus strains isolated from Parmigiano Reggiano cheese. Whereas the spatial differentiation of Stilton microbial communities has been established at the species level, there is a lack of information on biotypes at subspecies and strain levels. (2015), the observed properties of L. plantarum isolates could be of interest in developing Lactobacillus starters and starter culture adjuncts with improved resistance to multiple stresses for several applications including probiotics, where growth under harsh stress conditions would be an attribute. Antimicrobial activity was confirmed by using the paper diffusion assay (Albano et al., 2007) using Pseudomonas aeruginosa glaxo 3, Escherichia coli 0157: H7-stx, Listeria monocytogenes NCTC 11944, and Lactobacillus pentosus NCIMB 8026 which were the most sensitive strains from the agar overlay assays. Food Microbiol.

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Microbiol.

Reduction in activity when CFS-N and CFS-C were applied suggested that this activity was, in part, due to production of acid and hydrogen peroxide. (2004). Then, 0.1 ml of each sample was mixed with 0.9 ml MRD to obtain the initial dilution of 10–1.

DNA fingerprinting of Listeria monocytogenes strains by pulse-field gel electrophoresis. J. |, https://www.frontiersin.org/articles/10.3389/fmicb.2020.00904/full#supplementary-material, Creative Commons Attribution License (CC BY).

A novel method for rapid detection of class IIa bacteriocin-producing lactic acid bacteria. Acid and salt tolerance of selected L. plantarum isolates was evaluated using the approach of Succi et al. Enzyme treated supernatants were incubated for 30 min 37°C and the enzymes inactivated by boiling for 2 min. Environ.

Studies showed that the D65 values for the organism are higher in ham broth and slices than in laboratory media. Assays were performed in MRS broth supplemented with different salt concentrations (%, w/v): (◆) 0, control, (■) 3.5, (▲) 5, (X) 8, and () 10. 90, 4005–4021. Electrophoresis was performed in 2 L of 0.5X TBE buffer containing 100 μM thiourea in a contour-clamped homogenous electrophoresis cell (CHEF) DRII (Bio-Rad) at 14°C for 21 h at 6 V/cm and pulse times ramping linearly from 4 to 45 s at a switching angle of 120° and pump pressure of 80 rpm. Int. 1 0 obj Therefore, it was concluded that there were different strains or sub-populations of L. plantarum in the Stilton sample examined. 141, 117–124. brevis (strains R9 and R15, cluster III). (2009) proposed that occurrence, in cheese, of multiple strains of LAB belonging to the same species is, in most cases, the result of ecological selection following introduction into the cheese which may explain our data. The fermentation pattern of the other carbohydrates was species-dependent. Thermal tolerance of Lactobacillus viridescens in ham 117 However, it was found that to achieve this increase in thermal tolerance the increase in the heat applied had to be gradual.

29, 340–345. Typhimurium. Samples of the same cheese section were pooled and 1 ml volumes used for further 10-fold serial dilutions and subsequently plated on M17 agar (Oxoid) and standard Rogosa agar (pH 5.4 ± 0.2 at 25°C, Oxoid). L. plantarum isolates such as strains R4 and R5, which clustered close to each other, also had similar API profiles, demonstrating good correspondence of the two typing methods. This was true for cells inoculated at three different count levels (107, 104, and 102 CFU ml–1). The nature of antimicrobial activity was examined using CFS treated with 1N NaOH to bring the pH to 6.5–7 to neutralize acids and/or with 500 U ml–1 catalase (Sigma) to eliminate hydrogen peroxide.

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