Probiotic properties of lactic acid bacteria isolated from traditionally fermented Xinjiang cheese

Abstract

Abstract:Six lactic acid bacterial (LAB) strains were isolated from traditionally fermented Xinjiang cheese and evaluated for functional and probiotic properties and potentials as starter cultures. The isolated six LAB strains comprised Lactobacillus rhamnosus (one strain), Lactobacillus helveticus (one strain), and Enterococcus hirae (four strains). All of the six strains were tolerant to acidic and bile salt conditions. Among which, the L. rhamnosus R4 strain showed more desirable antimicrobial, auto-aggregation, and hydrophobic activity. In addition, the strain L. rhamnosus R4 exhibited the highest level of free radical scavenging activity (53.78% of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals and 45.79% of hydroxyl radicals). L. rhamnosus R4 also demonstrated cholesterol and triglyceride degradation by 50.97% and 28.92%, respectively. To further examine the health-promoting effects of these LAB strains on host lifespan, Caenorhabditis elegans was used as an in vivo model. Worms fed LAB as a food source had significant differences in lifespan compared to those fed Escherichia coli OP50 (as a negative control). Feeding of L. rhamnosus R4 extended the mean lifespan of C. elegans by up to 36.1% compared to that of the control. The results suggest that the strains isolated from Xinjiang fermented dairy products have high potential as starter cultures in the cheese industry.

Antimicrobial Activities of Lactic Acid Bacteria Strains Isolated from Human Breast Milk Against Human Pathogenic Strains

“…in this study, all tested strains indicated a proportion of growth above 69.8% in the present bile salt 0.3%, which demonstrated good bile salt tolerance. These results were consistent with previous study [3,9,11]. To further investigate the safety and functional characteristic of these strains as probiotic, tests were conducted to assess their antimicrobial activity.…”

“…Tolerance to acidic condition is the most commonly used method to detect the viability and activity of probiotic bacteria in the small intestine and stomach. According to a previous study [3,10]. The survival rate at pH 2 is considered as optimal acid tolerance for selected probiotic strains.…”

“…Similarly, [6] observed that L. acidophilus isolated from stock culture of yogurt in Iraq showed antimicrobial activity against Gram-positive bacteria; S. aureus, S. epidermis and bacilli that cause burn wound infections. Earlier reports showed that LAB isolated from human intestine have antimicrobial activity against a wide range of Gram-negative and Gram-positive pathogens in vitro and in vivo [3,10,1].…”

“…The ability to inhibit the pathogens of tested strains could be explaind by the production of antimicrobial compounds. According to the study of [3], the antimicrobial effect of LAB is due the production of metabolites, such as lactic acid, acetic acid, diacetyl, fatty acids, aldehydes bacteriocins and other compound, among which, lactic acid, acetic acid and bacteriocins are most powerful antimicrobial agents and are production of the probiotics. This study suggested that many compounds are responsible for the antimicrobial activity and can not be attributed to one or to main compounds present in breast milk human.…”

Insights into the microbial diversity and community dynamics of Chinese traditional fermented foods from using high-throughput sequencing approaches

“…These home-made products are fermented spontaneously by natural starter cultures from previous batches having complex microbial compositions (Hu et al, 2015;Azat et al, 2016). Understanding the microbial diversity and dynamics of these starters is important for the standardization of Chinese traditional fermented milk products.…”