Reddy Shetty Prakasham

Xylitol production by Candida sp.: parameter optimization using Taguchi approach

Abstract Xylitol production parameter optimization using a newly isolated Candida sp. was performed using Test plan L18, available in the form of an orthogonal array and a software for automatic design and analysis of the experiments, both based on Taguchi approach. Optimal levels of physical parameters and key media components namely temperature, pH, agitation, inoculum size, corn steep liquor (CSL), xylose, yeast extract and KH 2 PO 4 were determined. Among the physical parameters, temperature and agitation contribute higher influence. Media components CSL, xylose concentration and KH 2 PO 4 play an important role in the conversion of xylose to xylitol. The yield of xylitol under these optimal conditions was 78.9%.

L-asparaginase production by isolated Staphylococcus sp. -6A : design of experiment considering interaction effect for process parameter optimization

Aims:  Evaluation of fermentation process parameter interactions for the production of l‐asparaginase by isolated Staphylococcus sp. – 6A.

Alkaline protease production by an isolated Bacillus circulans under solid-state fermentation using agroindustrial waste: process parameters optimization.

Alkaline protease production using isolated Bacillus circulans under solid‐state fermentation environment was optimized by using Taguchi orthogonal array (OA) experimental design (DOE) methodology to understand the interaction of a large number of variables spanned by factors and their settings with a small number of experiments in order to economize the process optimization. The software‐designed experiments with an OA worksheet of L‐27 was selected to optimize fermentation (temperature, particle size, moisture content and pH), nutrition (yeast extract and maltose), and biomaterial‐related (inoculum size and incubation time) factors for the best production yields. Analysis of experimental data using Qualitek‐4 methodology showed significant variation in enzyme production levels (32000–73000 units per gram material) and dependence on the selected factors and their assigned levels. Validation of experimental results on alkaline protease production by this bacterial strain based on DOE methodology revealed 51% enhanced protease production compared to average performance of the fermentation, indicating the importance of this methodology in the evaluation of main and interaction effects of the selected factors individually and in combination for bioprocess optimization.

Enhancement of acid amylase production by an isolated Aspergillus awamori

Aims:  Evaluation of the influence of fermentation components on extracellular acid amylase production by an isolated fungal strain Aspergillus awamori.

Modelling and optimization of fermentation factors for enhancement of alkaline protease production by isolated Bacillus circulans using feed-forward neural network and genetic algorithm

Aim:  Modelling and optimization of fermentation factors and evaluation for enhanced alkaline protease production by Bacillus circulans.

Optimization of alkaline protease production by Bacillus sp. using taguchi methodology

Optimization of alkaline protease production parameters by Bacillus sp. was investigated using Taguchi methodology. The pH of the medium was observed to be the most significant factor among all selected optimization parameters at an individual level. The combinatorial influence of least significant factors, inoculum level and salt solution concentration (at the individual level), resulted in an interacting severity index of 76%, suggesting their interactive role in the regulation of protease production in this microbial species. Protease production could be improved more than 100% with Taguchi’s optimized conditions of the medium composition by this microorganism.

Neomycin production with free and immobilized cells of Streptomyces marinensis in an airlift reactor

Abstract Neomycin production by free and alginate immobilized Streptomyces marinensis cells was investigated in an airlift reactor. Neomycin production was increased two and a half times with immobilized cells. A marginal decrease in neomycin production was noticed with reduced supplementation of carbon source (up to one-fourth concentration). Immobilized S. marinensis particles showed a half-life of 20 days during continuous fermentation in an airlift reactor.

Mixture design as first step for improved glutaminase production in solid-state fermentation by isolated Bacillus sp. RSP-GLU

Aim:  Investigation of mixture‐design impact on glutaminase production by isolated Bacillus sp.

Studies on Improving the Immobilized Bead Reusability and Alkaline Protease Production by Isolated Immobilized Bacillus circulans (MTCC 6811) Using Overall Evaluation Criteria

This study uses an overall evaluation criterion for improving the immobilized bead reusability and extracellular enzyme production by immobilized cells by assigning relative weightage to bead reusability, enzyme production, and cell leakage. Initially, alkaline protease production by alginate-immobilized Bacillus circulans (MTCC 6811) was analyzed using L18 orthogonal array (OA). The resultant optimized parameters were further fine-tuned with L9 OA experimentation. At L18-OA analysis, inoculum level and CaCl2 had least influence at individual level. At the interactive level, incubation time revealed maximum and minimum interaction with sodium alginate and glucose concentration, respectively. L9 experimentation indicated that glucose concentration contributed the major influence on protease production followed by matrix material and incubation time at the individual level, and at the interactive level, matrix concentration played a vital role by interacting with incubation time, inoculum, and CaCl2 concentration. All selected input parameters showed significance either at individual level or interactive in both OAs. Scanning electron microscopy analysis showed bacterial morphology variation with variation of matrix concentration. Overall, glucose concentration depicted a major influence at the individual level for the enzyme production. Significant improvement, approximately 147%, in enzyme yield was observed. Economic enzyme production by immobilized B. circulans is regulated by interactive influence of fermentation parameters, which influence the immobilized bead stability, reusability, and enzyme yield.

Biohydrogen production process optimization using anaerobic mixed consortia: a prelude study for use of agro-industrial material hydrolysate as substrate.

Efficient biohydrogen production from lignocellulosic hydrolysate assumes considerable practical and academic importance. The impact of glucose to xylose ratio, medium pH, inoculum size and age on biohydrogen production indicated that glucose to xylose ratio is the critical parameter for effective H(2) production compared to either pure glucose or xylose as carbon source. Inoculum size and its age contributed more than 70% to overall H(2) production and revealed significance at individual as well as interactive level. Maximum interaction of 39% and 32% was noticed with inoculum size and its age vs. glucose to xylose ratio (2:3), respectively. The H(2) production yield enhanced from 140 to 357 ml/g substrate upon statistical optimization revealing >240% improvement.