' Biomass estimation of Aspergillus niger S , 4 a mangrove fungal isolate and A . oryzae NCIM 1212 in solid - state fermentation

The suitability of protein and glucosamine measurements of cell components for biomass estimation of fungi Aspergillus niger S,4, a mangrove isolate, and Aspergillus oryzae NCIM 1212 was evaluated using wheat bran as substrate in solid-state fermentation (SSF). Both direct as well as indirect methods were used. The protein and glucosamine contents and direct weight of the fungi were determined for 21 days and were found to vary significantly (P<O.O5) with the duration of SSF. The direct measurement of biomass showed two distinct peaks on day 1 I and 17 for A. niger and on day 12 and 17 for A. oryzae. In the case of the fortner, dry matter weight of the substrate gradually decreased as fermentation progressed with 68% loss on day 21. For the other species loss in dry matter content of substrate was only 30% on day 21. Glucosamine content showed three significant (P<0.05) peaks on day 3, 11 and 20 for A. niger and on day 3, 6 and 9 for A. oryzae. Protein content also showed three significant (P<0.05) peaks on day 2, 13 and 18 for A. niger and on day 2, 6 and 10 for A. oryzae. It has been concluded that the composition of the biomass as observed by measurement of protein and glucosamine contents typically varies during SSF and cannot be taken as standard procedures for biomass estimation. However, the results of the present stndy show that the process of SSF by A. niger for a period of 2-3 days can be applied for nutritional enrichment, four to six days for production of metabolites like enzymes and 6-21 days for bio-composting. A. oryzae can be effectively utilized for production of metabolites as well as nutritional enrichment.