Diversity of Lactobacillus Species of Stilton Cheese Relates to Site of Isolation

Abstract

This study has characterized the dominant non-starter Lactobacillus species isolated from different sites in a Stilton cheese to establish its diversity, stress-tolerance, antimicrobial activity and potential contribution to quality of cheese. Fifty-nine Lactobacillus isolates were cultured from the outer crust, blue veins and white core of the cheese and were speciated phenotypically and by 16S rDNA sequence analysis. Lactobacillus plantarum was the dominant species detected with only two isolates identified as Lactobacillus brevis. Strains were typed by pulse-field gel electrophoresis (PFGE) using the enzyme NotI to examine their genomic diversity. Cluster analysis of PFGE patterns produced five major clusters which associated isolates with their sites of isolation within the cheese. One L. plantarum isolate from each cheese site was selected and evaluated for salt, acid, relative humidity, and heat tolerance to determine whether stress conditions within the isolation site selected their phenotype. D 72 • C values were 6, 13, and 17 s for strains from the crust, veins and core, respectively, suggesting strains on the crust may not have been able to survive pasteurization and therefore had been added post-pasteurization. All strains recovered from heat injury within 24-48 h at 4 • C. pH values of 3, 3.5, and 4 suppressed growth but strains showed a varying ability to grow at pH 4.5 and 5; isolates from the core (which has the lowest pH) were the most acid-tolerant. All strains grew at 3.5 and 5% salt but were suppressed at 10%; those from the crust (which has a lower water activity) were the most halotolerant, growing at 8% salt whereas strains from the core were sensitive to this salt concentration. All 57 L. plantarum isolates were examined for antimicrobial activity and variable activity against Lactobacillus pentosus and other genera was demonstrated; plantaricin EF genes were present in 65% of strains. It was concluded that there are varied phenotypes and genotypes of Lactobacillus in a Stilton cheese according to site of isolation. Occurrence of different L. plantarum genotypes could contribute to variation in the cheese quality from batch to batch and provides criteria for selecting isolates as potential adjunct cultures.

Modelling the biphasic growth of non-starter lactic acid bacteria on starter-lysate as a substrate

“…The microbial ecology of cheese involves a rich and complex interaction between the starter lactic acid bacteria (SLAB) and the non-starter lactic acid bacteria (NSLAB). The SLAB in the cheese decline throughout ripening while growth of NSLAB increases as ripening progresses (Gantzias et al, 2020;Mugampoza et al, 2020;Settanni and Moschetti, 2010).…”

Probiotic Characteristics of Lactobacillus brevis KT38-3 Isolated from an Artisanal Tulum Cheese

“…Some of the L. brevis strains are known for their probiotic potential, and a few of them are employed as starter cultures ( Annuk et al, 2003 ). L. brevis is a common LAB species found in the microbiota of fermented cheeses ( Guley et al, 2014/15 ; Mugampoza et al, 2020 ; Skelin et al, 2012 ). The isolation of the L. brevis KT38-3 strain from artisanal Kargi Tulum cheese is in accordance with the data in the literature.…”

“…Some of the L. brevis strains are known for their probiotic potential, and a few of them are employed as starter cultures (Annuk et al, 2003). L. brevis is a common LAB species found in the microbiota of fermented cheeses (Skelin et al, 2012;Guley et al, 2014;Mugampoza et al, 2020).…”

Recent advances in the biosynthesis and industrial biotechnology of Gamma-amino butyric acid

“…Cocci, or rod-shaped, gram-positive, acid-tolerant, and non-sporing LAB is the key microorganism in GABA production (Yogeswara et al 2020b ). Furthermore, various Lactobacillus species, including, L. brevis (Mancini et al 2019 ; Seo et al 2013a ), L. buchneri (Mugampoza et al 2020 ), L. delbrueckii subs. Bulgaricus (Câmara et al 2019 ; Gangaraju et al 2014 ), L. plantarum (Zhuang et al 2018 ), and L. helveticus (Li et al 2020 ) have demonstrated significant potential in GABA biosynthesis and strong endogenous GAD activity.…”