Organic polymers, microbial attack

Since lignins are polymers of phenolics and are major plant constituents with resistance to microbial decomposition, they are the primary source of phenolic units for humic acid synthesis (178, 179). Once transformed, these humic acids become further resistant to microbial attack and can become bound to soils (180) form interactions with other high molecular weight phenolic compounds (ex. lignins, fulvic acids) and with clays (181) and influence the biodegradation of other organic substrates in soils (182, 183). 

Natural mbber, the other natural hydrocarbon polymer, consisting mainly of cfr-l,4-polyisoprene is relatively resistant to microbial attack in comparison to other natural polymers. A number of micro-organisms have been reported to degrade natural rubber. An enzyme which degrades the mbber was isolated from the extracellular culture medium of Xanthomonas sp., and the erude fractions which are capable of depolymerizing natural mbber in the latex state have been reported.The same authors " reported on a Nocardia strain that used natural mbber as its sole carbon source. 

---