Optimisation of biomass, exopolysaccharide and intracellular polysaccharide production from the mycelium of an identified Ganoderma lucidum strain QRS 5120 using response surface methodology

Wild-cultivated medicinal mushroom Ganoderma lucidum was morphologically identified and sequenced using phylogenetic software. In submerged-liquid fermentation (SLF), biomass, exopolysaccharide (EPS) and intracellular polysaccharide (IPS) production of the identified G. lucidum was optimised based on initial pH, starting glucose concentration and agitation rate parameters using response surface methodology (RSM). Molecularly, the G. lucidum strain QRS 5120 generated 637 base pairs, which was commensurate with related Ganoderma species. In RSM, by applying central composite design (CCD), a polynomial model was fitted to the experimental data and was found to be significant in all parameters investigated. The strongest effect (p lt 0.0001) was observed for initial pH for biomass, EPS and IPS production, while agitation showed a significant value (p lt 0.005) for biomass. By applying the optimized conditions, the model was validated and generated 5.12 g/L of biomass (initial pH 4.01, 32.09 g/L of glucose and 102 rpm), 2.49 g/L EPS (initial pH 4, 24.25 g/L of glucose and 110 rpm) and 1.52 g/L of IPS (and initial pH 4, 40.43 g/L of glucose, 103 rpm) in 500 mL shake flask fermentation. The optimized parameters can be upscaled for efficient biomass, EPS and IPS production using G. lucidum

Biodegradation kinetics of phenol by predominantly Pseudomonas sp in a batch shake flask

Biodegradation of phenol by predominantly Pseudomonas species isolated from a sewage wastewater treatment plant was investigated in batch shake flasks. Phenol with a lower concentration of 100 mg/L was degraded in 10 h and a highest of 800 mg/L in 69 h. The phenol degradation rate was observed to vary largely with the concentrations of phenol used and was found to be less than 10 mg/L/h at both the extremes of the initial concentrations. The degradation kinetics was found follow the three half-order kinetic model with the regression greater than 0.97. The specific substrate utilization rates of the culture at various initial phenol concentrations were fitted to modified substrate inhibition kinetic models of Edward, Haldane, Luong, Han-Levenspiel and Yano-Koga. Among these models the Edward was found to fit the data well with a minimum Root Mean Square error value of 0.0039

Biotechnology in Environmental Monitoring and Pollution Abatement 2015

Editoria

Biotechnology in environmental monitoring and pollution abatement

Editoria

Pyrene biodegradation by free and immobilized<i style=""> </i>cells of<i style=""> Mycobacterium frederiksbergense</i> using a solvent encapsulated system

496-501Polycyclic aromatic hydrocarbons (PAHs) are classified as hazardous pollutants in the environment due to their toxic, mutagenic and recalcitrant nature. Compared to other methods, biodegradation using microorganisms seems to be attractive alternative for treating PAH contaminated environment. However, there are limitations because of its low aqueous solubility and negligible bioavailability to the degrading microbes. The present study investigated biodegradation of pyrene, a model PAH compound, using both free and calcium alginate immobilized cells of Mycobacterium frederiksbergense. To overcome the bioavailability problem, organic phase (silicone oil) containing the PAH compound was encapsulated using chitosan coated sodium alginate-polyvinyl alcohol beads for subsequent use in the biodegradation experiments. Prior to the biodegradation experiments, characterization of the silicone oil encapsulated beads and the cell immobilized beads were also performed. In pyrene biodegradation experiments using the free cells, following an initial lag phase of 4 d, ~90% degradation was achieved at 400 and 800 mg/L initial pyrene concentrations. On the other hand, immobilized cells in beads of ~700 m size showed better performance even at a very high initial concentration of 2000 mg/L

Effect of process variables on the sulfate reduction process in bioreactors treating metal-containing wastewaters: factorial design and response surface analyses

The individual and combined effect of the pH, chemical oxygen demand (COD) and SO4 2− concentration, metal to sulfide (M/S2−) ratio and hydraulic retention time (HRT) on the biological sulfate reduction (SR) process was evaluated in an inverse fluidized bed reactor by factorial design analysis (FDA) and response surface analysis (RSA). The regression-based model of the FDA described the experimental results well and revealed that the most significant variable affecting the process was the pH. The combined effect of the pH and HRT was barely observable, while the pH and COD concentration positive effect (up to 7 and 3\ua0gCOD/L, respectively) enhanced the SR process. Contrary, the individual COD concentration effect only enhanced the COD removal efficiency, suggesting changes in the microbial pathway. The RSA showed that the M/S2− ratio determined whether the inhibition mechanism to the SR process was due to the presence of free metals or precipitated metal sulfides