EKOLOGIJA. 2011. T. 57. Nr. 2. P. 55–61 © Lietuvos mokslų akademija, 2011 Comparative shelf life and efficacy of LDPE and PVC degrading bacterial consortia under bioformulation Aditi Sah*, Harshita Negi, Anil Kapri, Shahbaz Anwar, Reeta Goel** Department of Microbiology, C. B. S. H., G. B. Pant University of Agriculture and Technology, Pantnagar-263145, Uttarakhand, India *Authors have contributed equally. ** Corresponding author. E-mail: rg55@redifmail.com Te present study elucidates the development of the talc-based formulation for long-term sustenance / storage of bacterial consortia, pertains to degrade polymer (LDPE and PVC). Four potential bacterial consortia were employed which consisted of Microbacterium sp., Pseudomonas putida, P. aeruginosa, P. otitidis, Bacterium Te68R, Bacillus aerius, B. cereus and Acanthopleurobacter pedis. Te viability of consortia was ascertained by measuring the colony forming units per mL besides assuring the polymer biodegradation potential afer formulation in talc by carrying out in vitro assays. Te analysis was done by determination of λ-max shifs and scanning electron microscopy for changes in polymer composition and surface dissolution, respectively. It reveals that using the described formulations, all the consortia were able to successfully retain their characteristic biodegradation property even afer 70 days of storage at ambient conditions. Furthermore, the SEM micrographs documented signifcant disruption of surface texture of polymer (LDPE and PVC) flm by respective consortia recovered afer storage. Tus, the talc-based formulation may be useful for the storage and handling of polymer-degrading consortia for large-scale applica- tions to minimize the solid waste disposal. Key words: biodegradation, bioformulation, talc, consortia, shelf life, LDPE, PVC, SEM INTRODUCTION Te extensive use of polymeric materials (plastics) during past decade in all the sectors of life has created serious pro- blems with plastic waste due to its accumulation in the en- vironment (Magan et al., 2010). Further, thermoplastics are inert materials and resistant to biodegradation because of its high molecular weight, long carbon chain backbone, three- dimensional structure, hydrophobic nature (Hadad et al., 2005; Kawai, 2010) and lack of functional groups recogni- zable by existing microbial enzyme systems (Chiellini et al., 2003). However, several attempts were made earlier to inves- tigate the microorganisms capable to utilize the thermoplas- tics (Onodera et al., 2001; Gilan et al., 2004; Booth et al., 2007; Shah et al., 2008; Gang et al., 2011). Further, the utilization of microbial consortia ofers considerable advantages over the use of pure cultures in the degradation of recalcitrant compounds considering its multifunctional ability and can be more robust to environmental fuctuations (Gilbert et al., 2003; Roy et al., 2008). Te carrier based formulation of microbial cells has long been established for applications in various felds like agricultural (Trivedi and Pandey 2008; Kumar et al., 2010), industrial (Tanaka et al., 1993) and pharmaceutical (Kaly- an et al., 2010) sectors. Te aim of formulating viable cells in carriers is to facilitate the delivery and handling proces- ses, and to ensure the adequate cell viability to maintain the efcacy of the cells (Bazilah et al., 2011). For bioreme- diation purposes, formulated microbial cells are ofen ap- plied using wet (liquid) formulations i. e. by spraying ino- culum suspensions on targeted sites, or using dry (solid) formulations like granules or dust (Sathiya moorthi et al., 2008). Te selection for the type of formulation developed and used is dependent on the nature of the active cells and factors related to the site of application such as aquatic or terrestrial landscapes and temperature, etc (Tu and Ran- dall, 2005). Most ofen, dry formulations are preferred over wet ones because they provide extended shelf life and are easier to store for long time and transport (Lumsden et al., 1995). In this context, four efcient polymer-degrading bac- terial consortia have been documented earlier. Among all, two consortia have documented to degrade synthetic po-