Abstract
Whey, a by-product of the dairy industry, acts as a prime source of environmental pollution due to its high organic load. Its utilization as a substrate for lipase production is an attractive option in facing the challenge associated with whey disposal. However, there are only very few studies that have reported the production of lipase using whey. In this study, 43 bacterial strains were isolated from dairy industry soil sample, of which, 26 were found to produce lipase. Since whey contains lactose as the sole carbon source, the ability of the isolates to utilize this sugar was tested and two of the isolates B3 and B10 were positive for growth in phenol red lactose broth. When they were cultured by submerged fermentation and their lipase activities quantified, strain B10 displayed 0.79U/ml of activity. In order to improve the production of lipase, one-factor-at-a-time method was used to study the impacts of oil inducers, nitrogen sources, mineral salts and whey concentration on the process. Statistical optimization was performed using the Box-Behnken design of Response Surface Methodology (RSM). From this design, 75% whey, 4% (v/v) sunflower oil, 0.625% (w/v) beef extract and 0.2% (w/v) CaCl2 were inferred to be the optimal conditions that resulted in a maximum lipase activity of 0.954U/ml. Analysis of variance indicated statistical significance of the model. Lipase being an industrially sought-after enzyme owing to its unique properties, this cost-effective route to its production from a waste substrate holds paramount environmental and economic significance.
Highlights
Whey, resulting from the processes of cheese making and casein manufacturing, is one of the by-products of dairy industry
The best isolate was subjected to optimization of lipase production using One-Factor-at-a-Time (OFAT) and Response Surface Methodologies (RSM)
Among the 43 isolates, 28 showed significant zone of lipid hydrolysis after 24h of incubation. These isolates from the primary screening were tested for true lipase activity in Rhodamine olive oil agar secondary screening
Summary
Whey, resulting from the processes of cheese making and casein manufacturing, is one of the by-products of dairy industry. The ability of lipase to undergo reverse reaction and synthesize triacylglyceride from glycerol and free fatty acids, discloses that it can catalyse a wide range of reactions such as hydrolysis, interesterification, esterification, alcoholysis, acidolysis and aminolysis (Joseph et al, 2008) It displays enzyme promiscuity, an ability to catalyse alternative reactions that differ from the natural physiological reaction. Considering the above facts, production of lipase from whey is a pertinent area of research and this study encompasses optimization of the production process using response surface methodology It enables effective medium optimization using a limited number of trials and has been widely employed for the optimization of a number of production processes. The best isolate was subjected to optimization of lipase production using One-Factor-at-a-Time (OFAT) and Response Surface Methodologies (RSM)
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