Biochemical Characteristics of Lactic Acid Bacteria with Proteolytic Activity and Capability as Starter Culture Isolated From Spontaneous Fermented Local Goat Milk

Abstract

This study was aimed to isolate  Lactic Acid Bacteria (LAB) from spontaneus fermented local goat milk, which had proteolytic activity and used for futher  fermentation of goat milk. Isolation of LAB was carried out by MRS Agar and CaCo₃.  Identification species of isolates was conducted according to the  Bergeys  manual (conventional method) and based on morphological, physiological and biochemical analysis using API 50 CHL kit was also carried out.  The results of identification and chemical test showed  that 26 isolates were identified as LAB were 16 isolates (61.5%) with rod shape and 10 isolates (38.5%) with cocci shape.  Based on proteolytic activity, the isolates composed of two bacteria species  namely Lactobacillus plantarum (YN1.1, YN1.3, YN 1.8 and isolates YN 2.25). and the other bacteria was Lactobacillus pentosus (YN 1.6.).  five isolates  had proteolytic activity, where three of them had the best proteolytic activity  namely  Lactobacillus plantarum YN 1.1, Lactobacillus plantarum YN 1.3 and Lactobacillus pentosus YN 1.6 . All of these isolates had the ability to ferment goat milk which was indicated by the increase of bacteria viability reaching up to 10⁹ cfu/ml and also decreaced of pH value at the final stage of fermentation.  It can be concluded that isolated LAB from spontaneous fermented local goat milk could be used as starter culture and could be inproved as commercial product.

Keywords: identification, API 50 CHL,Lactobacillus plantarum, Lactobacillus pentosus, viability, pH.