Internet Scientific Publications LLC, Texas, USA 2009 Volume 7 Number 1 ISSN: 1937-8289 Citation: C.K. Venil, N. Sangeetha Kamatshi & P. Lakshmanaperumalsamy : Statistical optimization of medium components for the production of lipase by Serratia marcescens SB08. The Internet Journal of Microbiology. 2009 Volume 7 Number 1 Statistical optimization of medium components for the production of lipase by Serratia marcescens SB08 CK Venil Division of Environmental Microbiology, Department of Environmental Sciences, Bharathiar University, Coimbatore - 641 046, Tamil Nadu, India. Email: ckvenil@gmail.com N Sangeetha Kamatshi Division of Environmental Microbiology, Department of Environmental Sciences, Bharathiar University, Coimbatore - 641 046, Tamil Nadu, India. Email: 83.sangeetha@gmail.com P Lakshmanaperumalsamy Division of Environmental Microbiology, Department of Environmental Sciences, Bharathiar University, Coimbatore - 641 046, Tamil Nadu, India. Email: drplpsamy@gmail.com Abstract The optimization of the fermentation medium and conditions for maximum lipase production was carried out using a new strain, Serratia marcescens SB08. The results of factorial design showed that CaCl 2 , incubation time, pH and yeast extract were the key factors affecting lipase production. The optimal cultural conditions for lipase production obtained with central composite design was pH 7.0, incubation time 51 h, yeast extract 3.0 g/L and CaCl 2 0.13 g/L. The model was also validated by repeating the experiments under the optimized conditions, which resulted in the lipase production of 243.91 U/mL (Predicted response 251.83 U/mL), thus proving the validity of the model. Lipase enzyme was purified and the molecular weight was found to be 52 kDa. In this work the use of a central composite design by determining the conditions leading to the high yield of enzyme production has been demonstrated. Thus, smaller and less time consuming experimental designs could generally suffice for the optimization of many fermentation processes. Keywords: Serratia marcescens | Lipase | Optimization | CCD 1. Introduction Lipases are extremely versatile enzymes, showing many interesting properties of industrial applications. They are a class of enzymes which catalyze the hydrolysis of long chain triglycerides and constitute the most important group of biocatalysts for biotechnological applications. Lipases can be divided generally into the following four groups according to their specificity in hydrolysis reaction: substrate specific lipases, regio-selective lipases, fatty acid specific lipases, and stereo -specific lipases. They are obtained from a variety of sources like plants, animals, yeast, bacteria; but among all, microbial lipases are the most popular for industrial use as they are easy to produce and are stable comparatively. Pancreatic lipase of porcine origin is one of the earliest recognized lipases and is still the best-known lipase. Plant lipases are not used commercially; the animal and microbial lipases are used extensively. Although there have been many papers dealing with the lipase producing yeasts such as Candida cylindracea, Saccharomycopsis lipolytica, Geotrichum candidum and Trichosporon fermentans, only limited research has been directed towards the lipase producing organisms. The most productive fungi species belong to the genera Geotrichum, Penicillium, Aspergillus and Rhizomucor. Lipases from unicellular bacteria, mainly those produced by various species of the genus Pseudomonas, have also proved to be useful both in organic reactions and in the detergent industry. Several microorganisms, such as Candida rugosa, Candida antarctica, Burkhoderia cepacia, and Pseudomonas alcaligenes, can produce lipase efficiently and their lipases are commercially available. A characteristic trait of many strains of Serratia marcescens is that they produce extracellular enzymes, including nuclease, protease, chitinase and lipase. Serratia species are gram-negative mesophills that have the capability to grow and produce extracellular lipase and protease during culture period. The early literature reported that S. marcescens isolated from raw milk produced lipase enzyme (Thomas, 1958; Witter, 1961). Recently, some workers have isolated psychrotrophs from refrigerated raw milk samples; about 3 to 6% of the isolated strains were S. marcescens (Milliere and Veillet-Poncet, 1985; Ahmed et al., 1989; Abdou, 1997). S. marcescens was found to have lipolytic and proteolytic activities (Abdou and Ohashi, 1996). The extracellular lipase from S. marcescens