Identification, Molecular Characterization and Evaluation of Some Ruminal Bacteria That Catalyze and Degrade Plant Cellulosic Materials

In the last few years there was a growing economic awareness about plant wastes and use it in compost production or in feeding of farm animals, some of these wastes are useless and cause a lot of problems in Egyptian environment. This study was designed to isolate, identify and evaluate some ruminal bacterial isolates to facilitate the in vitro degradation of certain local agro-industrial wastes (rice straw and corn stalks). Two bacterial isolates were isolated from rumen fluid of some Egyptian cattle and identified as Fibrobacter succinogenes and Ruminococcus albus depending on morphological, biochemical identification and molecular characterization using 16S rRNA genes. Two degenerate primers were used to detect about 1.6 kb PCR fragment, a partial sequences (709 and 401) bp were sequenced for F. succinogenes and R. albus respectively. The highest similarity was detected for both isolates which were 57% with Streptomyces sp. for F. succinogenes and 77% with Enterobacter sp. for R. albus. The two isolates were subjected in-vitro to catalyze and degrade rice straw and corn stalks. After four weeks of fermentation, degradation was measured depending on the bacterial growth and changes in chemical components of the degraded materials. The degradation of corn stalks was highly significant comparing to rice straw which inoculated by F. succinogenes or R. albus. Analysis of the chemical composition showed a decrease in Organic Matter (OM), Crude Fiber (CF), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), cellulose and hemicellulose content. The inoculum 7.5 mL/50 g of Ruminococcus albus is more efficient to degrade rice straw or corn stalks in four weeks fermentation period. Corn stalks are better than rice straw to enhance the cellulolytic bacteria to grow in all treatments.