Identification and characterization of lactic acid bacteria isolated from Tibetan Qula cheese

Abstract

Fourteen strains of Lactic Acid Bacteria (LAB) isolated from Qula, a Tibetan traditional yak cheese, were divided into four groups (A-D) according to morphological and biochemical characteristics. On the basis of the 16S rRNA gene sequence analysis, group A and group B strains were placed in the cluster making up the genus Leuconostoc, which together with Leuconostoc mesenteroides and Leuconostoc pseudomesenteroides, formed a distinct cluster. The group C strain was clearly identified as Enterococcus faecium by forming a very well defined cluster with this species. The group D strains were placed in the lactobacilli cluster with Lactobacillus plantarum and Lactobacillus pentosus being the closely related species. On the basis of DNA-DNA hybridization, strains in the groups A, B, C and D were identified as Leuconostoc mesenteroides subsp. dextranicum, Leuconostoc pseudomesenteroides, Enterococcus faecium and Lactobacillus plantarum, respectively. Leuconostoc mesenteroides subsp. dextranicum was the dominate member of the population.

Study on <i>Streptococcus thermophilus</i> isolated from Qula and associated characteristic of acetaldehyde and diacetyl in their fermented milk

“…However, S. thermophilus dominated, contributing to 33% of all cocci isolates. Bao et al (2012) also reported that S. thermophilus was the dominating species in Qula cheese (39%), whereas Tan et al (2010) and Duan et al (2008) reported that the dominating LAB was the Leuconostoc species (86% and 78%, respectively).…”

“…In particular, LAB plays an essential role in the formation of the aroma, texture, and acidity of the products. Previous studies showed that LAB is the dominant species in the microorganisms of Qula cheese, and play the most important role in the accumulation of nutrients (Bao et al, 2012;Duan et al, 2008). Some of the lactic acid bacteria are also known to have beneficial effects on human health (Mohd Adnan and Tan, 2007;Zhang, W. Y. et al, 2008).…”

Lactococcus nasutitermitis sp. nov. isolated from a termite gut

“…All members are Gram-stain-positive, catalase-negative, non-motile, non-spore-forming bacteria. Bacteria of the genus Lactococcus are widely distributed in a variety of fermented foods, dairy products, and plant and animal materials (Schleifer et al, 1985;Williams et al, 1990;Chen et al, 2001Chen et al, , 2014Duan et al, 2008). They have also been reported to be one of the most important lactic acid bacteria in the hindgut of wood-feeding termites (Bauer et al, 2000).…”

Isolation and identification of cultivable lactic acid bacteria in traditional yak milk products of Gansu Province in China

“…So, herders usually heat raw milk, and add an appropriate amount of kurut as a starter into cooled processed milk, and then allow the mixture to undergo fermentation naturally into kurut. If the kurut can be separated from whey and then dried, it becomes qula, which is usually a granular dried kurut solid without a shaping process (Duan et al, 2008). By the above processes, various kinds of fermented milks and derived products were produced using naturally occurring LAB developed in Gansu, each with its own characteristic history.…”

“…and many traditional dairy products like fermented yak milk, fermented goat milk, koumiss, butter, cheese, kefi r, whey and qula (Badis et al, 2004;Chena et al, 2008;Duan et al, 2008;Kongo et al, 2007;Liu et al, 2009;Ouadghiri et al, 2005;Watanabe et al, 2008;Zhang et al, 2008a, b). Therefore, more and more basic work on isolation, genotypic and phenotypic studies was applied to wild LAB, which were isolated from raw milk and traditional fermented dairy products (Cogan et al, 1997;Wouters et al, 2002).…”