Lignin Degradation by Isolated Lignolytic Acinetobacter baumanii S2, Aspergillus niger SF4 and Rhodotorula glutinis and Profiling Products from Bio-Valorization Perspective

With deployment of cellulosic ethanol there will be enhanced availability of lignin. Lignin, instead of low value utilization for heat generation, can be valorized for production of high value products. Ligninolytic organisms can be exploited for lignin valorization. Study was conducted to map lignin degradation and product profiles by Acinetobacter baumanii , Aspergillus and Rhodotorula strains. Bacterial strains Acinetobacter baumanii S1, S2, fungi Aspergillus nidulans and Aspergillus niger , isolated from compost through enrichment on lignin, were selected based on lignolytic enzyme activities and lignin degradation measured by decrease in absorbance at 205 nm. Highest lignin peroxidase 0.01 IU/mL and 0.36 IU/mL and lignin degradation 46.6% and 76.8% respectively by A. baumanii and A. niger were observed. LC–MS analysis of degraded lignins in alkali extracts of rice straw fermented with A. baumanii S2 , A. niger, Rhodotorula glutinis under solid state, showed distinct product profile for each organism and uninoculated control. Aromatic compounds vanillin, 6, 7- dihydroxy 4-methyl coumarin were produced in higher amounts by A. niger, A. baumanii predominantly produced coumarin, sinapic acid while R. glutinis treated extracts had ferulic acid and 2-hydroxy-cinamic acid. These aromatics are suitable for conversion to high- value products. Graphical Abstract