ORIGINAL PAPER Optimization of cultural conditions for tannase production by Pseudomonas aeruginosa IIIB 8914 under submerged fermentation Manjit K. Selwal • Anita Yadav • Krishan K. Selwal • N. K. Aggarwal • Ranjan Gupta • S. K. Gautam Received: 15 May 2009 / Accepted: 5 October 2009 / Published online: 22 October 2009 Ó Springer Science+Business Media B.V. 2009 Abstract A tannase yielding bacterial strain was isolated from soil sample collected from the area situated nearby small-scale tannery. It was identified as Pseudomonas aeruginosa IIIB 8914. The bacterial strain produced extra- cellular tannase under sub-merged fermentation (Smf) using amla (Phyllanthus emblica), keekar (Acacia nilot- ica), jamoa (Eugenia cuspidate) and jamun (Syzygium cumini) leaves. Among different substrates, amla and keekar leaves resulted in maximal extra-cellular production of tannase. Various process parameters were studied to optimize the extra-cellular yield of tannase under Smf. Maximum yield of tannase i.e., 13.65 and 12.90 U/ml was obtained when Smf was carried out using amla and keekar leaves (2% w/v) respectively in minimal media supple- mented with MgSO 4 Á7H 2 O (amla)/HgCl 2 (keekar), NH 4 NO 3 and 0.2% Tween 80; inoculated with 2% cell suspension, and incubated at 37°C for 24 h. The bacterial strain produced about 2 times (13.65 U/ml) higher yield of tannase than the highest reported yield of tannase (6 U/ml). Our finding suggests that agro residues in the form of amla and keekar leaves can be one of the best and cost effective alternatives to the costly pure tannic acid for industrial production of microbial tannase. Keywords Tannase Á Pseudomonas aeruginosa Á Submerged fermentation Á Agro residues Á Tannins Introduction Tannin acyl hydrolase (E.C.3.11.20) commonly referred as tannase is an inducible enzyme that catalyzes the hydro- lysis of ester and depside bonds in hydrolysable tannins to produce glucose and gallic acid (Deschamps et al. 1983). It finds widespread applications in the food, beverage and pharmaceutical industries (Aguilar et al. 2007). Most of the commercial applications of tannase are in the manufac- turing of instant tea, wine, beer and coffee-flavored soft drinks where it is used to eliminate the water-insoluble precipitates. Other important application of tannase is the production of gallic acid and propyl gallate. The former is used in the pharmaceutical industry for the synthesis of antibacterial drugs and in the food industry as substrate for the chemical synthesis of food preservatives while the later is a very important food antioxidant. Most of the reported tannase-producing organisms are fungi (Aguilar et al. 2007). For industrial applications, a major problem in the utilization of fungal strains is that the degradation by fungi is relatively slow. It is also difficult to manipulate fungal strains genetically due to their com- plexity. Most of the tannin degrading bacteria are isolated from ruminants and possess the ability to degrade tannin anaerobically (O’Donovan and Brooker 2001; Nishitani et al. 2004; Sabu et al. 2006). The processes based on anaerobic bacteria for the study of tannin degradation are M. K. Selwal Á A. Yadav (&) Á S. K. Gautam Department of Biotechnology, Kurukshetra University, Kurukshetra, Haryana 136119, India e-mail: ntydv@yahoo.com K. K. Selwal Dairy Microbiology Division, National Dairy Research Institute, Karnal, Haryana 132001, India N. K. Aggarwal Department of Microbiology, Kurukshetra University, Kurukshetra, Haryana 136119, India R. Gupta Department of Biochemistry, Kurukshetra University, Kurukshetra, Haryana 136119, India 123 World J Microbiol Biotechnol (2010) 26:599–605 DOI 10.1007/s11274-009-0209-x