Bioconversion of lignocelluloses from paddy straw to Vanillic Acid using Aspergillus niger

Abstract

Lignocellulosic materials are important natural renewable resources. This is because it is low in cost, renewable and it requires low processing energies. Agricultural residues, such as paddy straw are sources for lignocellulosic materials. Paddy straws are unique in their chemical compositions as well as their chemical, physical and mechanical properties. Its consist mainly of cellulose, hemicelluloses, lignin and a small amount of extractives. A number of different pretreatment methods of lignocellulosic materials to release lignin, cellulose and hemicelluloses are addressed such as chemical and steam pretreatment. Alkaline hydrolysis was choosed as the most suitable method to release ferulic acid for low low lignin content biomass. Optimum conditions for vanillic acid obtained from alkaline hydrolysis using Sodium Hydroxide, NaOH of paddy straw at different temperature (80ºC, 90ºC, and 100ºC) and NaOH concentration (3M, 4M and 5M) were 3M NaOH, 100ºC for 3 hours which yielded 0.02% of ferulic acid. The results obtained showed that lower concentration of NaOH, high temperature and longer reaction time have favored the ferulic acid formation. A vanilic acid concentration of 0.000567g was obtained after 3 days of fermentation at 30 ºC and pH at 5.5 using Aspergillus niger as the fermentative organism. Nevertheless, the yield of vanillic acid on this study was relative lower due to the fact that lower concentration of ferulic acid obtained from this study.