Bioactive compounds obtained from Coriolus versicolor (Trametes versicolor (L.: Fr) Lloyd, 1920.) mushrooms cultivated in a stirred-tank bioreactor were tested to determine their antimicrobial potential. Extracellular polysaccharides were isolated from the fermentation broth by ethanol precipitation. A methanol extract was prepared from mycelium. The cultivation conditions applied during the fermentation process provided for significant biomass 6.63 ± 0.31 g dry weight L− 1 and yield of extracellular polysaccharides (EPS) (0.74 ± 0.12 g L− 1). Microscopic analyses revealed that the mycelium grew predominately in the form of fluffy pellets. The methanol extract demonstrated very good activity against all the tested Gram-positive bacteria. Bacillus spizizeni and Staphylococcus epidermidis were the most sensitive strains (minimum inhibitory concentration (MIC) Our results suggested that the submerged cultivation of Coriolus versicolor followed by ethanol precipitation of EPS and the methanol extraction of mycelia can be a promising process to obtain biological active compounds with significant antimicrobial activity. Industrial Relevance Mushrooms contain a large number of chemicals with potential use as antimicrobial compounds. One of the biggest challenges for providing biologically active compounds from mushrooms is short-term process standardization with a low risk for contamination. Submerged culture cultivation is the best choice for providing antimicrobial compounds from mushrooms. The submerged culture method represents an effective and energy-efficient means to produce novel antibacterial compound from mushrooms. Antibacterial activity testing revealed that methanol extract and isolated exopolysaccharides exhibited strong antibacterial activity, especially against Gram-positive bacteria.

Advances in batch culture fermented Coriolus versicolor medicinal mushroom for the production of antibacterial compounds

Studies on laccase production by Daedalea flavida were carried out in static and low-speed shake cultures. The enzyme production was reduced drastically at a high speed of shaking. Optimal production conditions are necessary to assess the quality of laccase suitable for a specific application. Thus, the production of laccase was optimized by the application of response surface methodology. Laccase production was 8-fold and 7.5-fold more in static and low-speed shake conditions, respectively, in an optimal medium composition than in an unoptimized medium. Laccase obtained using the optimal culture medium of D. flavida was tested for its stability at different temperatures and pH conditions. The partially purified enzyme was most stable at 30°C and pH 5. The half-life of laccase is 87 min at 60°C and at pH 6. The kinetic and thermodynamic parameters were evaluated for the inactivation of the partially purified laccase. The entropy change of inactivation of the enzyme is least at pH 4.

Optimization of laccase fermentation and evaluation of kinetic and thermodynamic parameters of a partially purified laccase produced by Daedalea flavida.

Various options in biotechnology have been exercised to produce industrially important metabolites from fila- mentous organisms. To select a suitable production strategy, the direct and indirect roles of morphological parameters in controlling bioprocess variables are observed. Some progress has been made in quantitation of morphology.Useful corre- lations have been reported in the literature in this avenue. Of course, some of the models, with proper modification, can be used to explain the morphological phenomena. This review is concerned with the application of morphological variables to correlate with bioprocess parameters for explaining optimal production strategy.

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G.N. Rameshaiah

Papers

Application of Actinobacterial and Fungal Morphology on the Design ofOperating Strategies in Bioprocess Development