Screening of Efficient Polymer Degrading Bacteria and Influence of Various Pre-treatment on Degradation

Abstract

Community level physiological profiling (CLPP) by Ecoplate® method was performed for characterization of whole microbial community. All the soil sample were differ in their substrate utilization pattern. Microbial community is evenly distributed in all the soil environment and utilize maximum carbon sources as a substrate except dumpsite soil sample. Total 39 bacteria were isolated from soil samples and plastic attached soil collected from the Pirana dumpsite, Ahmedabad. From this 12 isolates having different colony characteristics were used for the study of degradation efficiency. This study showed that isolates PDS31, PDS34 and PDS36 have higher efficiency for biofilm formation compare to other isolates. While isolates PDS15 and PDS2 showed the invert proportion in suspended growth and biofilm formation. Biofilm formation efficiency and suspended growth of P. citronellolis was found higher when inoculated into MSM medium as compare to isolated organism from the dump site. Heat, UV, and Alkali pretreatment was given to the four types of plastics such as HDPE, LDPE, PP, Composite. The minimum growth of P. citronellolis was confirmed by spectrophotometer analysis on all types of pre-treated polymer. When it was analyzed for its ability to survive in presence of such complex substrate, it was found to grow slowly on the different types of polymer. It was further confirmed by SEM analysis. Bacterial colonization, cracks, holes, and patches were observed on the surface of UV and alkali pre-treated composite polymer. So it can be concluded that heat pre-treatment is not much effective as other pre-treatment for the colonization. The change in physical and chemical properties was observed by UTM and FT-IR analysis. UTM analysis shows the 30 % reduction in tensile strength of only biologically treated composite (without any pre-treatment) compare to control. Whereas it showed higher significant increase in tensile strength of all three pre-treated sample which may be due to effect of pre-treatment on the annealing process of polymer. Prolong incubation may enhance the suspended growth of P. Citronellolis and shows the significant effect on polymer degradation.