Isolation, characterization, and molecular identification of probiotics showing promising hypoglycemia operating activities

Abstract

Background Probiotics are the most useful microorganisms for animal and human health; they are used in the pharmaceutical and food industries for many products that enhance digestion and immunity. Objective The objective of our study was to isolate, characterize, and identify a probiotic bacterial strain and determine its hypoglycemia operating parameters. Materials and methods Our research was carried out through the isolation of probiotic colonies from milk samples on MRS medium. Bacterial isolates were characterized both morphologically and biochemically. The collected bacterial isolates were tested for their low pH tolerance on phosphate buffer pH 2.0 and bile salt tolerance in MRS-THIO liquid medium. Glucose assimilation activity was tested by measuring the residual glucose concentration on MRS liquid medium at 37°C after 24 and 48 h by GOD-PAP enzymatic colorimetric method. The initial glucose concentration was 500 mg/dl. The most potent isolate was identified by methods of 16S-rDNA sequencing. Results and conclusion Twenty-one bacterial isolates were isolated and characterized. Bacterial isolates showed the highest resistance to acidic pH 2.0 and they were bile-tolerant. Results of glucose assimilation showed that there was a marked increase in sugar consumption rate after 48 h more than 24 h in most of the bacterial isolates. The top 10 isolates were selected for the testing of the rest of the parameters. Results show that no noticeable differences were observed in the consumption of glucose in the low-glucose concentration, but with more glucose concentration more glucose consumption rate differences were recorded among organisms. The top two organisms that have the ability to reproduce and consume glucose even in high-glucose concentrations were Ab 9 and Ab 2 with results of glucose residual concentration of 108 and 124 mg/dl, respectively. The phylogenetic tree showed that the most potent isolate Ab 2 was identified as Lactobacillus brevis.