Production of beta-carotene-enriched rice bran using solid-state fermentation of Rhodotorula glutinis

This work was aimed at utilizing rice bran as a substrate for beta-carotene production by Rhodotorula glutinis DM 28 under optimized conditions of solid-state fermentation. The biomass and beta-carotene content of Rhodotorula glutinis DM 28 grown on rice bran as a sole substrate under solid-state fermentation were 54 g/kg rice bran and 1.65 mg/kg rice bran, respectively. Its biomass and beta-carotene content, however, could be improved by 60% and 30%, respectively, using the Central Composite Design for the optimization of its cultivation conditions. The optimized conditions obtained were a pH of 5, a moisture content of 70% (w/w), and a carbon-to-nitrogen ratio of 4. Under these conditions, rice bran containing R. glutinis DM 28 had nutritional values of beta-carotene, protein, and fat higher than those of rice bran alone. Yeast-grown rice bran could be suitable, therefore, to use as a beta-carotene-enriched supplement in animal feeds.

Optimization of beta-carotene production by Rhodotorula glutinis DM28 in fermented radish brine

A face-centered central composite design was applied to optimize a cultivation condition for improved beta-carotene production by Rhodotorula glutinis DM28 in a stirred tank reactor using 30 g/l total soluble solid of fermented radish brine as a sole substrate. The experiments were performed with regression models, where temperature, pH and dissolved oxygen were considered as variables. Results showed that an optimum condition for beta-carotene production of the yeast was at 30 degrees C, pH 6 and 80% dissolved oxygen. Under this condition, the yeast yielded 2.7 g/l biomass and the maximum beta-carotene of 201 microg/l after 24-h fermentation indicating approximately 15% higher than those under an initial condition (2.3g/l and 178 microg/l, respectively).

Feather degradation by Bacillus sp. FK 46 in submerged cultivation

Cultivation conditions affecting feather degradation by Bacillus sp. FK 46 were investigated. The results showed that feather was almost completely degraded under the following conditions: 1% whole chicken feather as a substrate at the initial medium pH of 9 with 5% bacterial inoculum, at a temperature of 37 degrees C and a shaking speed of 250 rev/min. Glucose, methanol, Tween 80 and Triton X-100, however, had no effect on feather degradation. After feather was degraded, its residue and fermented broth would become a protein feed for animals.

Fungal chitosan production and its characterization

AIMS

The objective of this investigation was to evaluate the chitosans produced by several species of fungi.

METHODS AND RESULTS

Representatives of four species of filamentous fungi, Aspergillus niger, Rhizopus oryzae, Lentinus edodes and Pleurotus sajo-caju, and two yeast strains, Zygosaccharomyces rouxii TISTR5058 and Candida albicans TISTR5239, were investigated for their ability to produce chitosan in complex media. Fungal chitosan was produced at 10-140 mg g-1 cell dry weight, had a degree of deacetylation of 84-90% and a molecular weight of 2.7 x 104-1.9 x 105 Da with a viscosity of 3.1-6.2 centipoises (cP).

CONCLUSIONS

Rhizopus oryzae TISTR3189 was found to be the producer of the highest amounts of chitosan.

SIGNIFICANCE AND IMPACT OF THE STUDY

Commercial chitosan could be obtained from Rhizopus mycelia and would have potential applications for medical and agricultural uses.