Selection of potential lactic acid bacteria from fermented Sumbawa mare’s milk as starter cultures

Abstract

The aim of this study was to screen lactic acid bacteria (LAB) isolates from fermented Sumbawa mare's milk that meet the requirements as starter cultures, and to evaluate the effect of the selected starter culture in improving the organoleptic quality of mare's milk fermentation. Methodology and results: The LAB isolates (13 isolates) derived from naturally fermented Sumbawa mare's milk were firstly screened for acidification activity. Afterwards, the selected isolates were evaluated for the starter culture criteria such as technological properties (proteolytic test, lipolytic test, and exopolysaccharide production), food safety test (hemolytic test and antibiotic sensitivity test), antimicrobial activity test. The selected culture (SC) together with yogurt starter cultures (YC) and combination between the selected isolate and a mixture of both (MC) were used to ferment fresh mare's milk. Six LAB isolates (DB7, BC10, DC4, BC9, DC10, and BC7) were obtained from the acidification screening. Isolate BC10 was the most potential isolate as starter culture due to its ability in terms of acidification and proteolytic activity, lack of lipolytic activity, no indication of pathogenic potency, as well as able to inhibit the growth of Escherichia coli ATCC 25922. However, this isolate was resistant to antibiotics kanamycin, trimethoprim, and cinoxacin. The isolate BC10 presented 99.99% sequence similarity with respect to Lactobacillus plantarum. Conclusion, significance and impact of study: The selected starter culture (isolate BC10) was able to improve the organoleptic quality of fermented mare's milk especially aroma compared to the other starter cultures. Therefore, Lactobacillus plantarum BC10 is a potential isolate to be used as starter culture for mare's milk fermentation.

Isolation and Screening of Lactic Acid Bacteria From Sumbawa Buffalo Milk (Bubalus bubalis) as Potential Starter Cultures

“…The other isolates were classified as soft-type colonies. However, the soft-type colony which did not form sticky threads produced a high EPS concentration which was detected quantitatively [17].…”

“…The resistance to kanamycin has also been reported before. Four out of six LAB isolates from Sumbawa fermented mare's milk products were resistant to kanamycin [17]. Microbial resistance to antibiotics is caused by the excessive use of antibiotics and causes selective pressure on the proliferation of microorganisms [39].…”

“…The proteolytic activity was conducted using a 1% skim milk agar medium, which was enriched with 0.05% NaCl, 0.1% yeast extract, 0.2% tripton, 0.01% CaCl2, and 1.5% Bacto agar [17]. The 24-h LAB cultures were equalized using a spectrophotometer with a wavelength of 600 nm, and then 50 μL of the cultures were dripped onto a blank disk (Oxoid, UK).…”

“…The antibacterial activity test was performed using the disk-diffusion agar [17]. The indicator bacteria used were Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Salmonella Typhi.…”

“…The amplicon was confirmed using gel agarose electrophoresis (1.5%) and then sequenced at 1 st BASE, Malaysia. The sequences were analyzed for constructing a phylogenetic tree using MEGA 6 software with the Neighbor-Joining algorithm and the Tamura-Nei model with a bootstrap of 1000 [17].…”