New Tools for Exploring “Old Friends—Microbial Lipases” Saisubramanian Nagarajan Received: 7 January 2012 / Accepted: 20 August 2012 / Published online: 6 September 2012 # Springer Science+Business Media, LLC 2012 Abstract Fat-splitting enzymes (lipases), due to their natural, industrial, and medical relevance, attract enough attention as fats do in our lives. Starting from the paper that we write, cheese and oil that we consume, detergent that we use to remove oil stains, biodiesel that we use as transportation fuel, to the enantiopure drugs that we use in therapeutics, all these applications are facilitated directly or indirectly by lipases. Due to their uniqueness, versatility, and dexterity, decades of research work have been carried out on microbial lipases. The hunt for novel lipases and strategies to improve them continues unabated as evidenced by new families of microbial lipases that are still being discovered mostly by metagenomic approaches. A separate database for true lipases termed LIPABASE has been created recently which provides taxonomic, structural, biochemical information about true lipases from various species. The present review attempts to summarize new approaches that are employed in various aspects of microbial lipase research, viz., screening, isolation, production, purification, improvement by protein engineering, and surface display. Finally, novel applications facilitated by microbial lipases are also presented. Keywords Microbial lipases . Metagenomic approaches . Laboratory evolution . Surface display Lipases are triacylglycerol hydrolases (E.C.3.1.1.3) that catalyze the hydrolysis and synthe- sis of long chain acyl glycerol with trioleyl glycerol being standard substrate (Fig. 1)[1]. Lipases are unique because of their interfacial nature, viz., the substrates (lipids) are insoluble in water, whereas the enzymes are soluble in water, and hence, these enzymes catalyze the reactions at the lipid–water interface involving interfacial adsorption and subsequent catalysis. Lipases generally do not require cofactors for their catalytic activity. Lipases belong to the structural superfamily of α/β hydrolases [2] and mostly possess a conserved pentapeptide Gly-X-Ser-X-Gly motif. The active serine is usually located in a Appl Biochem Biotechnol (2012) 168:1163–1196 DOI 10.1007/s12010-012-9849-7 S. Nagarajan (*) School of Chemical and Biotechnology, SASTRA University, Thirumalaisamudram, Thanjavur 613401, Tamil Nadu, India e-mail: sai@scbt.sastra.edu