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LIGNOCELULOSIC WASTE AS CARBON SOURCE FOR THE PRODUCTION OF BIOPOLIESTERS BY BACTERIA ISOLATED FROM FOREST SOIL
Agave bagasse was chemically hydrolyzed (catalyst, 2% sulfuric acid, particle size, 40 mesh, solids content, 10%, temperature, 130 °C, time, 20 min) to obtain fermentable sugars (xylose, 7.21 g/L; glucose, 3.09 g/L). Subsequently the hydrolyzate was treated with activated charcoal (50 g/L, agitation 4 h), to eliminate microbial growth inhibition compounds, centrifuged and neutralized (pH 7). This hydrolyzate was used for the production of biopolyesters by a bacterium belonging to the genus Achromobacter (isolated from a forest soil sample) in a two-stage process: 1. Biomass production for 48 h (hydrolyzate with addition of yeast extract and peptone); 2. Accumulation of the polymer during 48 h (recovery of biomass from stage 1 and inoculation in hydrolyzate without nitrogen source). Also, the microorganism was cultivated using xylose and glucose as a carbon source (10 g/L). Subsequently the bacterial biomass was recovered and the polymer was extracted and characterized by FTIR and NMR. The production of biomass (g/L) and accumulation of PHA (%) for each carbon source was: xylose (4.13 g/L, 31.3%), glucose (1.95 g/L, 16.9%), hydrolyzed agave (1.36 g/L, 8%). The spectra obtained by FTIR and NMR indicated that the bacterium synthesized from each carbon source polyhydroxybutyrate (PHB) which is an homopolymer of 3-hydroxybutyric acid.