Catechol-2,3-Dioxygenase and Crude Oil Biodegradation Screening of Rhizo-Bacterial Endophytes from Bodo-Gokana, Rivers State

Abstract

Strain-selection for the biotechnological application is critical in modern environmental bioremediation process design. In this study, twenty-one rhizobacterial isolates were obtained from the rhizosphere soil of Cyperus sp., Cyperus rotundus, Mariscus alternifolius and Maricus ligularis. Samples were treated using Bushnell-Haas media fortified with Bonny light crude oil plus 1% (v/v) rhizosphere soil from pre-impacted locations in Bodo-Ogoni, Gokana LGA, Rivers state. They were screened and four bacterial isolates were selected on the basis of -2,3 catechol dioxygenase activity and their growth dynamics using the growth function model in XLSTAT v 2019.1.3. Vapour-phase transfer and viable plate count techniques were employed in the determination of microbial dynamics. The order for relative enzyme activity and degradation rates followed Pseudomonas fluorescens > Achromobacter agilis > Bacillus thuringiensis > Staphylococcus lentus. The order for growth range were 7.0-10.5 Log10CFU/ml, 6.2-10.3 Log10CFU/ml, 7.1-10.1 Log10CFU/ml and 6.4-10.2 Log10CFU/ml for Achromobacter agilis > Pseudomonas fluorescens > Bacillus thuringiensis > Staphylococcus lentus. The growth pattern of these isolates fitted into the 5th order polynomial function (y= pr1+pr2*X+pr3*X2+pr4*X3+pr5*X4+pr6*X5) with R2-values of 0.999, 0.998, 0.991,0.999 compares to Gompertz and Asymptotic functions that have the least predictability with R2- values of 0.893, 0.599, 0.869, 0.894 and 0.80, 0.545, 0.829, 0.688 for the four isolates respectively. Enzyme activity of the isolates revealed that the isolates were most active on the 6th day of the study and had a lag phase within the first few hours to a day of the study. Statistical analyses revealed a significant difference using two-way ANOVA; p< 0.001 for both enzyme activity and growth rate. The results underscore the benefits and richness of rhizobacterial flora as rich in enzymatic activity for ecosystem-recovery. Overall, the study has shown the great potential and feasibility for deploying robust biotechnology for the monitoring of environmental media involving hydrocarbon pollution in the Niger Delta.