Kinetics of endoglucanase and cellobiohydrolase production by parent and mutant derivative of moderately thermotolerant Bacillus subtilis GQ 301542 on optimized medium

A moderately thermotolerant bacterial strain was isolated from the hot spring of Tatta Pani (AJ and K) Pakistan and was designated as Bacillus subtilis strain GQ 301542 after biochemical, morphological and 16S rDNA sequence analysis. This strain and its catabolite repression resistant mutant CRM197 were utilized for the study of different production kinetic parameters of both endoglucanase and cellobiohydrolase. Time course study on one monomeric (glucose), one dimeric (maltose) and two polymeric substrates (-cellulose and wheat straw) was carried out at different time intervals (4 - 28 h, after each 4 h) for determining the maximum enzyme productivity on a particular substrate. Maximum rate of endoglucanase production by the mutant (53.1 IU/L/h) was significantly (P = 0.0007) higher than that (23.7 IU/L/h of the parental organism following their growth on glucose in Dubos salts medium while the optimum product yields (Yp/s) was calculated as 69.0 IU/g S (parent) and 82.3 IU/g S (mutant) for cellobiohydrolase production. Deoxy-D-glucose resistant mutant was significantly (p = 0.03 to 0.0007) improved over its parental strain with respect to some substrate consumption and all product formation parameters and can easily degrade cellulosic biomass for production of fermentable carbohydrates.Key words: Cellobiohydrolase, endoglucanase, thermotolerant, Bacillus subtilis

Somaclonal variations for red rot and sugarcane mosaic virus resistance and candidate genes integrity assessment in somaclones of selected sugarcane varieties (Saccharum officinarum L.)

Sugarcane is a complex allopolyploid hybrid with erratic flowering due to various geo-climatic factors hence deliberate hybridization for varietal improvement is a dilemma in most of the countries where sugarcane is cultivated. Somaclonal variations is an alternate strategy used for development of disease resistance and improvement in yield attributes, but point mutation in candidate genes is questionable. The aim of this study was to develop somaclones resistant to red rot and Sugarcane mosaic virus (SCMV) in obsolete sugarcane varieties and their genetic integrity assessment in candidate gene’s exon regions. A total of 581 somaclones were developed, of which 201 survived after hardening and 121 after transplantation and screened against red rot and SCMV. Only 10% somaclones were found resistant to red rot in susceptible and moderately susceptible varieties while SCMV concentration was recorded less than negative control in somaclones. Four candidate genes namely; catalase (CAT1), sucrose phosphate synthase (SPS), gibberellin 2-xidase 4 (GA 2-oxidase 4) and tillering branched 1 (TB1) were evaluated for possible SNPs in their exon regions. Sequences of five representative somaclones were aligned with their parental clones and no possible SNP changes were observed. Somaclonal variations was a good source of genetic improvement of sugarcane for disease resistance with no SNP changes in candidate genes.</p