Biopulping of bagasse by Cryptococcus albidus under partially sterilized conditions

• Production of cellulose degrading enzymes like CMCase was negligible.
• SEM analysis showed surface colonization and pit formation.
• FT-IR analysis indicates cellulose enrichment.
• Dominance of Cryptococcus albidus under partially sterilized condition.
• Increase in kappa number/viscosity ratio after treatment.

Cryptococcus albidus was used for biopulping bagasse under partially sterilized conditions to access its potential industrial application in the pulp and paper industry. Enzyme analysis of C. albidus treated bagasse samples was carried out at different time periods (days 15, 30, and 60). Another set of bagasse was maintained in similar culture conditions without C. albidus inoculum (control) to assess the effect of C. albidus treatment. The proportion of cellulose degrading enzymes was found to be much lower (3.0–3.5%) as compared to the control samples (21–56%). Scanning electron microscopy (SEM) clearly demonstrated surface colonization and pit formation. Fourier-transformation infrared spectroscopy (FT-IR) indicated the chemical modification of bagasse. The signature peak for cellulose was found to be prominent in C. albidus treated samples. Denaturing gradient gel electrophoresis (DGGE) confirmed the presence of C. albidus throughout the experiments. It was evident that C. albidus was able to suppress the growth of a native population. After 60 days both control and treated bagasse were given a kraft pulping treatment. The kappa number of C. albidus treated bagasse decreased by 42% while in control samples it was found to be decreased by 39% only. There was increase in viscosity/kappa number ratio after treatment.