Pilot scale study on steam explosion and mass balance for higher sugar recovery from rice straw.

Pretreatment of rice straw on pilot scale steam explosion has been attempted to achieve maximum sugar recovery. Three different reaction media viz. water, sulfuric acid and phosphoric acid (0.5%, w/w) were explored for pretreatment by varying operating temperature (160, 180 and 200°C) and reaction time (5 and 10min). Using water and 0.5% SA showed almost similar sugar recovery (∼87%) at 200 and 180°C respectively. However, detailed studies showed that the former caused higher production of oligomeric sugars (13.56g/L) than the later (3.34g/L). Monomeric sugar, followed the reverse trend (7.83 and 11.62g/L respectively). Higher oligomers have a pronounced effect in reducing enzymatic sugar yield as observed in case of water. Mass balance studies for water and SA assisted SE gave total saccharification yield as 81.8% and 77.1% respectively. However, techno-economical viability will have a trade-off between these advantages and disadvantages offered by the pretreatment medium.

Assessment of changes in community level physiological profile and molecular diversity of bacterial communities in different stages of jute retting.

Retting of jute is essentially microbiological and biochemical in nature. Community Level Physiological Profiles (CLPP) as well as genomic diversity of bacterial communities were assessed in water samples collected during pre-retting, after 1st and 2nd charges of retting. The water samples were collected from two widely cultivated jute growing locations, Sonatikari (22 degrees 41'27"N; 88 degrees 35'44"E) and Baduria (22 degrees 44'24"N; 88 degrees 47'24"E), West Bengal, India. The CLPP, expressed as net area under substrate utilization curve, was studied by carbon source utilization patterns in BIOLOG Ecoplates. Molecular diversity was studied by polymerase chain reaction followed by denaturing gradient gel electrophoresis (PCR-DGGE) of total DNA from water samples. Both between locations and stages of retting, substrate utilizations pattern were carbohydrates > carboxylic acids > polymers > amino acids > amines/amides > phenolic compounds. Differential substrate utilization pattern as well as variation in banding pattern in DGGE profiles was observed between the two locations and at different stages of retting. The variations in CLPP in different stages of retting were due to the change in bacterial communities.