Enhancement of cellulase production by co-culture of <i>Streptomyces ambofaciens</i> OZ2 and <i>Cytobacillus oceanisediminis</i> OZ5 isolated from rumen samples
Mustafa Özkan Baltacı
Abstract
Cellulose is considered to be an alternative form of energy, and has recently gained significance representing millions of dollars for countries that have the opportunity to obtain energy from it. At the same time, cellulosic biomaterials are attractive since they are both cheap and abundant. To use this important resource, its stubborn structure must be broken down. Rumen bacteria are regarded as unique for this job. In this study, 17 cellulolytic bacteria were isolated from rumen samples collected from Erzurum slaughterhouses. Three bacteria (OZ2, OZ5, OZ17) with maximum enzyme activity were identified by sequencing the 16S rRNA gene region. As a result of the sequence analysis, it was determined that isolates belong to Streptomyces ambofaciens OZ2, Cytobacillus oceanisediminis OZ5, and Streptomyces violaceochromogenes OZ17. Then, cellulase production potentials of these identified bacteria were investigated as single and co-cultures. The co-culture of OZ2 and OZ5 demonstrated the best cellulase activity (26 U/mL). As a result of the optimization studies for the co-culture of OZ2 and OZ5, the best culture conditions were 3 g/L yeast extract, 60 h incubation time, pH 6, and temperature 35 °C. Under optimized conditions, the cellulase enzyme activity increased approximately 3.5-fold to 56 U/mL.