Degradation of lignin and lignin model compound under sulfate reducing condition

The release of depolymerization products of lignin during the degradation o f lignocellulsic material under sulfate reducing condition was investigated . In addition, we investigated the fate of the most common (beta -O-4) link present in lignin under sulfate reducing condition, using a lignin model c ompound. The method of investigation was based on the selective inhibition of microbial uptake of released aromatic phenolic compounds, depolymerizati on product of lignin, by toluene. Eight different aromatic phenolic compoun ds were identified. Until day 17 only 3 phenolic compounds were regularly d etected, thereafter 7 aromatic phenolic compounds could be regularly identi fied. The accumulation of identified phenolic acid was not linear with time . The lignin model compound was completely degraded within 13 days when eit her Avicel cellulose or newspaper was present as alternate source of carbon . On the other hand when lignin model compound was present as the sole sour ce of carbon, it took more than 22 days for its complete degradation. But i n either case complete degradation of lignin model compound was observed. F our degradation byproducts of lignin model compound were identified, but th e two most significant compounds identified were vanillic acid and 3-methox y-4-hydroxy benzene propionic acid. The GC/MS analysis of the degradation b y products of lignin model compound indicated that beta -O-4 link was cleav ed under sulfate reducing condition and the presence of additional carbon s ource enhanced this process.