Recombinant cellulase of Caulobacter crescentus: potential applications for biofuels and textile industries

Caulobacter crescentus ( C. crescentus ) has a single celA gene encoding the bacterial cellulase (EC 3.2.1.4) of the GH9 family that is induced at transcriptional levels (q-PCR) by agroindustrial residues. Corn straw (1%, w/v) was more efficient in inducing bacterial mRNA-celA expression than corn cob (1%, w/v) and a parallel protein expression profile was observed, since enzyme activity was also higher in presence of corn straw in the bacterium. In order to evaluate the biotechnological role of cellulase from C. crescentus (NA1000), the celA gene of 1,878 bp (CCNA_02310) was cloned in the pTrCHisA vector and successfully expressed in Escherichia coli . The recombinant cellulase CelA purified showed 73 kDa, specificity to CMC, optimal pH of 5.5 and pH stability of 6, optimal temperature at 40 °C and thermostability at 35 °C, K M = 0.66 mg/mL and V Max = 2.41 U/mg/min. CelA was strongly activated by ions Mn 2+ (70%), Sn 2+ (49%) and Co 2+ (46%) and was efficient in the hydrolysis of corn straw and corn cob (1%; w/v) releasing 2.62 µmol/mL and 1.02 µmol/mL of reducing sugar, respectively, being an alternative for the production of chemicals and biofuels. CelA was applied directly to the jeans fiber and scanning electron micrographs (SEM) generated showed a clean and smooth surface of the fibers compared to the control, indicating the application of enzyme for the biopolishing of denim jeans. This work supports a set of biotechnological capabilities of cellulase from C. crescentus suggested by the bacterial genomic sequence that has not been described yet. Graphic abstract