Identification of new rubber-degrading bacterial strains from aged latex

Rubber waste management plays an important role to deal with high production and consumption of rubber. In order to find an alternative for current rubber waste management, rubber-degrading bacteria were isolated from aged latex. Among the 13 isolates obtained, isolate CFMR-7 showed clear zone formation around its colonies on the latex overlay agar. Phase-contrast light microscope and scanning electron microscope (SEM) analysis showed that this strain contains branched conidial filaments. Besides, CFMR-7 showed its ability to degrade latex glove whereby, increment of dry biomass weight, increase in roughness of latex glove surface and bacterial colonization on the latex glove. Analysis of 16S rRNA gene sequence revealed that CFMR-7 is 99% identical to Streptomyces sp. whereas isolates CDRG-7 and CFR-4 are 99% identical to Gordonia sp. Subsequently, partial fragment of putative latex clearing protein (lcp) gene was successfully amplified from Streptomyces sp. CFMR-7, Gordonia sp. CDRG-7 and Gordonia sp. CFR-4. Amplified DNA fragment from Streptomyces sp. CFMR-7 exhibited 81% identity to both Streptomyces sp. K30 and Streptomyces sp. LCIC4 lcp gene, whereas those from Gordonia sp. CDRG-7 and Gordonia sp. CFR-4 showed 99% and 78% identity to lcp gene of Gordonia polyisoprenivorans VH2 and Gordonia westfalica Kb1 respectively. Streptomyces sp. CFMR-7 was subjected to whole genome sequencing and full length lcp gene with 1242 bp was obtained. It showed only 77% identity to the nucleotide sequence and 73% identity to the amino acid sequence of the reported lcp gene from rubber-degrading Streptomyces. Analysis of the sequences shows that Streptomyces sp. CFMR-7 and Gordonia sp. CFR-4 are different from the reported rubber-degrading bacteria, suggesting further characterization and exploitation in rubber waste management.