Isolation, Characterization and Identification of Industrially Beneficial Probiotic Lactic Acid Bacteria from Goat Milk

Purpose: Goat’s milk is enriched with many nutrients and diverse lactic acid bacteria (LAB). This research was aimed at isolating and characterizing industrially beneficial probiotic lactic acid bacteria present in goat milk and to investigate their ability to produce lactic acid.

Research Method: A total of 100 bacterial isolates were obtained from 20 fresh goat’s milk samples from Western and North Western provinces in Sri Lanka. These isolates were characterized based on their colony and cell morphologies, physiological and biochemical characteristics, tolerance to in-vitro gastro intestinal tract (GIT) conditions and industrial properties. Species level identification of the isolates was performed based on the obtained phenotypic properties according to the Bergey’s manual of systematic bacteriology.

Findings: The selected eight probiotic LAB isolates did not produce hemolytic enzymes, therefore, could primarily consider as safe for live consumption. According to the phenotypic properties, the isolates were of Lactobacillus pentosus, Lactobacillus plantarum, Streptococcus thermophilus, Streptococcus bovis, Lactococcus lactis and Enterococcus faecium species. They were able to coagulate skimmed milk which was indicated by the decrease of fi nal pH (4.8-5.9), tolerate to high (45 °C) and low (15°C) temperatures, grow in different NaCl concentrations (2%, 4%, and 6.5%) and different pH levels (1.5-3.9). HPLC analysis revealed that, Lactobacillus pentosus (33 mg/L) and Streptococcus thermophiles (14mg/L) possessed the highest lactic acid production abilities.

Research Limitations: The species level identification of the isolates should be continued employing genotypic methods. The safety of the isolates for live consumption should confirm with in-vivo methods.

Originality/Value: The raw goat milk microbiota is considered as a good source of novel lactic acid bacteria (LAB) strains that can be exploited for use as industrial starters and probiotics. Lactic acid produced by the microorganisms; specifically, lactic acid bacteria is an important commodity chemical having many numbers of applications. However, very less research work has been done on the characterization of beneficial lactic acid bacteria present in goat milk produced in Sri Lanka.