Growth and Substrate Utilization Patterns of a Rhizopus stolonifer Strain Isolated from Depolymerising Rice Husk

A study was carried out on a new strain of Rhizopus stolonifer RCH7 isolated from a spontaneouslyfermenting rice husk sample. Growth characteristics on and utilization profile of various substrates by this isolate were investigated. The isolate was found to display the most extensive mycelia proliferation at a temperature of 37°C and a pH of 4.0. Divalent ionic additions did not cause an increase in the growth rate, but 0.1M potassium ions increased the growth recorded by 34.3% compared to the control by 72 hours. This isolate was able to effectively utilize Carboxymethylcellulose and Polygalacturonic acid as alternate nutritive substrates demonstrating a growth of 90mm and 86mm respectively by 72 hours. The dry mycelia mass of R. stolonifer obtained from the cultivation in broth containing lactose was 26mm while that in glucose broth was 24mm. The growth and substrate utilization profile exhibited by this R. stolonifer RCH7 isolate is suggestive of its strong capacity to employ residues of agricultural wastes as growth substrates. It is also an indication of the isolate’s potential to degrade ‘agricultural waste residues, especially those from rice plant parts’.