Vijay Kumar Garlapati

Enzymatic transesterification of Jatropha oil

BackgroundTransesterification of Jatropha oil was carried out in t-butanol solvent using immobilized lipase from Enterobacter aerogenes. The presence of t-butanol significantly reduced the negative effects caused by both methanol and glycerol. The effects of various reaction parameters on transesterification of Jatropha oil were studied.ResultsThe maximum yield of biodiesel was 94% (of which 68% conversion was achieved with respect to methyl oleate) with an oil:methanol molar ratio of 1:4, 50 U of immobilized lipase/g of oil, and a t-butanol:oil volume ratio of 0.8:1 at 55°C after 48 h of reaction time. There was negligible loss in lipase activity even after repeated use for seven cycles.ConclusionTo the best of our knowledge this is the first report on biodiesel synthesis using immobilized E. aerogenes lipase.

Bioconversion technologies of crude glycerol to value added industrial products

Highlights • Crude glycerol is a byproduct of biodiesel industry.• Crude glycerol is a valuable source for different valuable industrial products.• Bioconversion of glycerol is a sustainable approach.• This makes revenue to biodiesel industries and to overall economy of the biodiesel process.

Optimization of laccase production using response surface methodology coupled with differential evolution

In the present study, laccase production from a locally isolated hyperactive strain of Pleurotus sp. under solid state fermentation (SSF) was carried out and the interactions between different parameters of fermentation were studied using response surface methodology. The saddle shaped response surface plots depicting dual conditions for the enhanced production indicated the presence of isozymes with production optima at different conditions which was verified experimentally. Isoelectric focusing of the enzyme extract revealed that two isoforms were found with a widely varying pI of 3.8 and 9.3 emphasizing the capacity of the enzyme to be deployed at both acidic and alkaline conditions. Optimization of production conditions by coupling the regression equation with differential evolution technique yielded over 54,600IU/gds (3,412,500U/L) with a surfactant concentration of 0.016%, pH 7.99, particle size of 0.25cm, liquid to solid ratio of 4.99 and an incubation period of 8 days. In this study, the optimization process yielded highest titer value of laccase reported to date.

Solvent-Free Synthesis of Flavour Esters through Immobilized Lipase Mediated Transesterification.

The synthesis of methyl butyrate and octyl acetate through immobilized Rhizopus oryzae NRRL 3562 lipase mediated transesterification was studied under solvent-free conditions. The effect of different transesterification variables, namely, molarity of alcohol, reaction time, temperature, agitation, addition of water, and enzyme amount on molar conversion (%) was investigated. A maximum molar conversion of 70.42% and 92.35% was obtained in a reaction time of 14 and 12 h with the transesterification variables of 0.6 M methanol in vinyl butyrate and 2 M octanol in vinyl acetate using 80 U and 60 U immobilized lipase with the agitation speed of 200 rpm and 0.2% water addition at 32°C and 36°C for methyl butyrate and octyl acetate, respectively. The immobilized enzyme has retained good relative activity (more than 95%) up to five and six recycles for methyl butyrate and octyl acetate, respectively. Hence, the present investigation makes a great impingement in natural flavour industry by introducing products synthesized under solvent-free conditions to the flavour market.

The selective role of nitrite in the PAO/GAO competition

Proliferation of Glycogen Accumulating Organisms (GAOs) accounts as one of the major bottlenecks in biological phosphorus removal systems. GAO outcompeting polyphosphate accumulating organisms (PAOs) results in lower P-removal. Thus, finding optimal conditions that favour PAO in front of GAO is a current focus of research. This work shows how nitrite can provide a novel strategy for PAO enrichment. A propionate-fed GAO-enriched biomass (70% Defluviicoccus I, 18% Defluviicoccus II and 10% PAO) was subjected more than 50 d under anaerobic-anoxic conditions with nitrite as electron acceptor. These operational conditions led to a PAO-enriched sludge (85%) where GAO were washed out of the system (<10%), demonstrating the validity of the new approach for PAO enrichment. In addition, the presented suppression of Defluviicocus GAO with nitrite represents an add-on benefit to the nitrite-based systems since the proliferation of non-desirable GAO can be easily ruled out and added to the other benefits (i.e. lower aeration and COD requirements).

Evolutionary and swarm intelligence-based approaches for optimization of lipase extraction from fermented broth

Evolutionary and swarm intelligence‐based optimization approaches, namely genetic algorithm (GA) and particle swarm optimization (PSO), were utilized to determine the optimal conditions for the lipase extraction process. The input space of the nonlinear response surface model of lipase extraction served as the objective function for both approaches. The optimization results indicate that the lipase activity was significantly improved, more than 20 U/g of dry substrate (U/gds), in both approaches. PSO (133.57 U/gds in the 27th generation) outperforms GA (132.24 U/gds in the 320th generation), slightly in terms of optimized lipase activity and highly in terms of convergence rate. The simple structure associated with the effective memory capability of PSO renders it superior over GA. The proposed GA and PSO approaches, based on a biological phenomenon, are considered as natural and thus may replace the traditional gradient‐based optimization approaches in the field of downstream processing of enzymes.

Evaluation of a New Lipase from Staphylococcus sp. for Detergent Additive Capability

Lipases are the enzymes of choice for laundry detergent industries owing to their triglyceride removing ability from the soiled fabric which eventually reduces the usage of phosphate-based chemical cleansers in the detergent formulation. In the present study, a partially purified bacterial lipase from Staphylococcus arlettae JPBW-1 isolated from the rock salt mine has been assessed for its triglyceride removing ability by developing a presoak solution so as to use lipase as an additive in laundry detergent formulations. The effects of selected surfactants, commercial detergents, and oxidizing agents on lipase stability were studied in a preliminary evaluation for its further usage in the industrial environment. Partially purified lipase has shown good stability in presence of surfactants, commercial detergents, and oxidizing agents. Washing efficiency has been found to be enhanced while using lipase with 0.5% nonionic detergent than the anioinic detergent. The wash performance using 0.5% wheel with 40 U lipase at 40°C in 45 min results in maximum oil removal (62%) from the soiled cotton fabric. Hence, the present study opens the new era in enzyme-based detergent sector for formulation of chemical-free detergent using alkaline bacterial lipase.

Modeling, Simulation, and Kinetic Studies of Solvent-Free Biosynthesis of Benzyl Acetate

Solvent-free biosynthesis of benzyl acetate through immobilized lipase-mediated transesterification has been modeled and optimized through statistical integrated artificial intelligence approach. A nonlinear response surface model has been successfully developed based on central composite design with transesterification variables, namely, molarity of alcohol, reaction time, temperature, and immobilized lipase amount as input variables and molar conversion (%) as an output variable. Statistical integrated genetic algorithm optimization approach results in an optimized molar conversion of 96.32% with the predicted transesterification variables of 0.47 M alcohol molarity in a reaction time of 13.1 h, at 37.5°C using 13.31 U of immobilized lipase. Immobilized lipase withstands more than 98% relative activity up to 6 recycles and maintains 50% relative activity until 12 recycles. The kinetic constants of benzyl acetate, namely, and were found to be 310 mM and 0.10 mmol h−1 g−1, respectively.

Modelling and Optimization Studies on a Novel Lipase Production by Staphylococcus arlettae through Submerged Fermentation.

Microbial enzymes from extremophilic regions such as hot spring serve as an important source of various stable and valuable industrial enzymes. The present paper encompasses the modeling and optimization approach for production of halophilic, solvent, tolerant, and alkaline lipase from Staphylococcus arlettae through response surface methodology integrated nature inspired genetic algorithm. Response surface model based on central composite design has been developed by considering the individual and interaction effects of fermentation conditions on lipase production through submerged fermentation. The validated input space of response surface model (with R 2 value of 96.6%) has been utilized for optimization through genetic algorithm. An optimum lipase yield of 6.5 U/mL has been obtained using binary coded genetic algorithm predicted conditions of 9.39% inoculum with the oil concentration of 10.285% in 2.99 hrs using pH of 7.32 at 38.8°C. This outcome could contribute to introducing this extremophilic lipase (halophilic, solvent, and tolerant) to industrial biotechnology sector and will be a probable choice for different food, detergent, chemical, and pharmaceutical industries. The present work also demonstrated the feasibility of statistical design tools integration with computational tools for optimization of fermentation conditions for maximum lipase production.

The path forward for lignocellulose biorefineries: Bottlenecks, solutions, and perspective on commercialization

Lignocellulose biorefinery encompasses process engineering and biotechnology tools for the processing of lignocellulosic biomass for the manufacturing of bio-based products (such as biofuels, bio-chemicals, biomaterials). While, lignocellulose biorefinery offers clear value proposition, success at industrial level has not been vibrant for the commercial production of renewable chemicals and fuels. This is because of high capital and operating expenditures, irregularities in biomass supply chain, technical process immaturity, and scale up challenges. As a result, commercial production of biochemicals and biofuels with right economics is still lagging behind. To hit the market place, efforts are underway by bulk and specialty chemicals producing companies like DSM (Succinic acid, Cellulosic ethanol), Dow-DuPont (1,3-Propanediol, 1,4-Butanediol), Clariant-Global bioenergies-INEOS (bio-isobutene), Braskem (Ethylene, polypropylene), Raizen, Gran-bio and POET-DSM (Cellulosic ethanol), Amyris (Farnesene), and several other potential players. This paper entails the concept of lignocellulose biorefinery, technical challenges for industrialization of renewable fuels and bulk chemicals and future directions.