nr

Natural rubber (NR)

Natural rubber (NR) is synthesized by a wide variety of plants with more than 2,000 species known. The main type of the natural rubber (NR) is based on poly(cis-1,4-isoprene) (Rose & Steinbüchel, 2005; Yikimis, 2012). The annual world production of NR was in 2020 reported to be at about 13 million tons and the synthetic rubber production was at 14 million tons (rubberstudy.org). Since biologically synthesized poly( cis-1,4-isoprene) does not accumulate in the environment, natural degradation seems to be the most likely way of environmental removal. Microorganisms capable to degrade NR are affiliated with the genera of Gordonia, Mycobacterium, Nocardia and Rhodococcus, Streptomyces, Actinoplanes, Micromonspora, Steroidobacter and others. Also a number of NR-active enrichment cultures were published recenly (Nguyen, 2020).

While the capability of microorganisms to degrade natural rubber is potentially relatively widespread, surpriningly only very few enzymes have been characterized in detail. Microbial NR polymer degradation is initiated by oxidative enzymes and cleavage of the double bonds within the polymers. Few well studied types of enzymes appear to be involved in NR degradation. The best studied enzyme types are: Lcp from Streptomyces sp. K30 which is a latex clearing protein that is encoded together with two other oxidases oxiA and B. Lcp is a b-type cytochrome and acts as an endo-type dioxygenase producing C20 and higher oligo-isoprenoids that differ in the number of isoprene units but have the same terminal functions, CHO-CH2– and –CH2-COCH3 (Birke, 2017; Ilcu 2017; Jendrossek, 2019).
Rox A is a (rubber) dioxygenase and it has two c-type heme centers. It differs from classical cytochrome c peroxidases. RoxA was derived from Steroidobacter cummioxidans (Xanthomonas) sp.35Y. RoxA and Lcp both catalyze an oxidative C-C cleavage. RoxB (LatA) is yet another type of rubber oxygenase from Steroidobacter cummioxidans (Xanthomonas) sp. 35Y (Jendrossek, 2019).

Microbial host/enzyme/geneReferenceGenBank/ UniProtPDB entryNCBI BLAST
Bacteria
Streptomyces sp. K30, Lcp, LCP_STRK3Yikmis, 2012; Rose,2005; Yikmis,2008Q3L8N0501lQ3L8N0.2
Steroidobacter cummioxidans (Xanthomonas ) 35Y, RoxATsuchii,1990Q7X0P34B2NQ7X0P3
Steroidobacter cummioxidans (Xanthomonas) 35Y, RoxBTsuchii,1990A0A1S6Q8F9 AQV11968.1
R. gummiphilus NS21, LatAKasai 2017LC073705 LC073705.1
Streptomyces sp. AC04842, Lcp1Basik, 2022
Streptomyces sp. AC04842, Lcp2Basik, 2022
Microtetraspora sp. AC03309, Lcp1Basik, 2021
Microtetraspora sp. AC03309, Lcp2Basik, 2021
Dactylosporangium sp. AC04546Basik, 2021


  • nr.txt
  • Last modified: 2022/06/14 15:13
  • by Wolfgang Streit