Characterization of Lactobacillus, Bacillus and Saccharomyces isolated from Iranian traditional dairy products for potential sources of starter cultures.

Farzad Rahmati

doi:10.3934/microbiol.2017.4.815

Abstract

The aim of the present study was to investigate technological properties of starter strains from traditional dairy products collected from five villages of Lorestan province in Iran. Thirty five samples were cultured on selective media (MRS broth, Nutrient Broth and YGC and then typical colonies checked for morphological features and eventually eighty two strains selected for further examination. The strains were evaluated for Hydrolysis of casein, starch and citrate, growth at 15 and 45 °C, growth in 4 and 6.5% NaCl, resistance to antibiotics (ampicillin, bacitracin, chloramphenicol, erythromycin, gentamicin, penicillin, novobiocin, nalidixic acid) proteolytic and lipolytic and acidification activities. Sixteen strains chosen according to the difference in cell morphology and were identified using API galleries and ability to metabolize various carbohydrates, which consequently, led to identifying seven Lactobacillus casei, five Lactobacillus plantarum, two Saccharomyces cerevisiae and two Bacillus subtilis. In general, two strains of L. casei AKL2, DDL2, two strains of L. plantarum SYL5, ACL4 and one strain of S. cerevisiae DDy2 was demonstrated the most important technological characterization that suitable for using as starter cultures.

Highlights

Since milk provides the conditions for microbial growth, such as water activity, pH close to neutral and reach of nutrients is a suitable place for many microorganisms
Since Lactobacillus strains were able to grow at 15 °C but did not grow at 45 °C, so they considered as mesophile Lactobacillus sp. [13]
Referring to the table fermentation of carbohydrates by mesophile hetrofermentative Lactobacillus in Bergey’s manual, L. plantarum due to fermentation both raffinose and melibiose are distinguishable compared with L. casei was able to ferment neither of carbohydrates

Summary

Introduction

Since milk provides the conditions for microbial growth, such as water activity, pH close to neutral and reach of nutrients is a suitable place for many microorganisms. Starter culture microorganisms used in fermentations belong to family of bacteria collectively known as LAB. Studies conducted in Iran in the field of Lactobacillus are more aimed at the food industry to optimize the quality of dairy products, biochemical characteristics and identification. The scope of this study was isolation and study of technological characteristic of starters Lactobacillus, Bacillus and Saccharomyces from traditional dairy products. By this effort , we are capable of isolating and preserve these strains for commercial applicability to prevent annual output of millions of dollars from the country, and produce dairy products in accordance with Iranian taste

Methods

Results

Conclusion