Poly(-1,4-isoprene)-cleavage enzymes from natural rubber-utilizing bacteria.

Natural rubber and synthetic poly(-1,4-isoprene) are used industrially in the world. Microbial utilization for the isoprene rubbers has been reported in gram-positive and gram-negative bacteria. Poly(-1,4-isoprene)-cleavage enzymes that are secreted by rubber-utilizing bacteria cleave the poly(-1,4-isoprene) chain to generate low-molecular-weight oligo(-1,4-isoprene) derivatives containing aldehyde and ketone groups. The resulting products are converted to the compounds including carboxyl groups, which could then be further catabolized through β-oxidation pathway. One of poly(-1,4-isoprene)-cleavage enzymes is latex-clearing protein (Lcp) that was found in gram-positive rubber degraders including , and species. The other one is rubber oxygenase A and B (RoxA/RoxB) which have been identified from gram-negative rubber degraders such as and . Recently, the transcriptional regulation mechanisms for Lcp-coding genes in gram-positive bacteria have been characterized. Here, the current knowledge of genes and enzymes for the isoprene rubber catabolism were summarized.