Isolation and identification of halophilic bacteria producing exopolysaccharides from whey and milk permeate

Abstract

The aim of this research was to study the utili-zation ability of the salt whey and milk permeate to produce exopolysaccharides (EPSs) from halo-philic bacteria. Where cheese whey is simultane-ously an effluent with nutritional value and a strong organic and saline content. However, it is drained in the sewers, the EPSs are highly heterogeneous polymers produced by different species of bacteria and have recently been attracting considerable attention from biotechnologists because of their potential applications in many fields. Thus, we have isolated some halophilic bacteria that showed the ability to produce EPS from whey and milk permeate. A total of 46 strains of moderately halo-philic bacteria were isolated from two types of samples. The first type was dairy samples (Bar-amily cheese whey and mish cheese), while the second type was water samples (salty lake water and its sediments) of Wadi El-Natrun Valley (lakes Hamra, UmRisha, and Baida), Beheira Gover-norate, Egypt. From isolated strains there are twelve strains were having the ability to produce exopolysaccharides but only seven strains can produce EPS from whey and milk permeate. The growth conditions i.e. concentrations of NaCl, pH value and different incubation temperature, of iso-lates were determined. The effect of these condi-tions on the production of EPS was investigated. The obtained results indicated that the optimum conditions for the production of EPS by these strains were 10 % NaCl, pH 7 and the optimum incubation temperature was 37°C. Three strains showed the highest production of exopolysaccha-rides. These strains were identified using two methods the first method was biolog system and the second one was 16S rRNA sequence analysis method. It could be identified as Alteribacillus bid-golensis and Bacillus licheniformis. Alteribacillus bidgolensis (strain P4B) produced the highest amount of EPS (52 g/L) from whey followed by Bacillus licheniformis (DSM 13) (42 g/L), while the highest amount of EPS produced from milk perme-ate was (43 g/L) by Alteribacillus bidgolensis (strain P4B) followed by Bacillus licheniformis (DSM 13) (36 g/L).