Bioprospecting of Halotolerant Bacterial Isolates for Potassium Recovery from K-Feldspar Potassium-solubilizing bacteria were isolated from solar salt pans of an experi- mental salt farm and Sambhar Lake, mining areas of Naseerabad, and wastewater from a marble cutting machinery. Seven promising bacterial isolates from Makra- na, three from Sambhar Lake, and three from Naseerabad were found to have comparatively better potassium-solubilizing capacity. Out of these, three potential bacterial isolates were identified as Acinetobacter soli (MTCC 5918), Enterobacter xiangfangensis (MTCC 5917), and Acinetobacter baumannii (MTCC 5916). A. soli was found to have maximum potassium-releasing capacity in the supernatant which may be further applied as a biofertilizer. Keywords: Fermentation, Fertilizers, Halotolerant bacteria, Potassium solubilization, Sea water Received: September 15, 2015; revised: March 28, 2016; accepted: July 05, 2016 DOI: 10.1002/ceat.201500561 1 Introduction Potassium is an important chemical element required for plant growth and reproduction. It helps in starch formation, controls root growth, and regulates the stomatal movement in plant cells [1]. The availability of K to plants and microbes exist in different forms, e.g., water-soluble, exchangeable, non-exchange- able, and minerals, where the first two forms are easily available to plants but the latter two involve different mechanisms for making it available to soil. Microorganisms play a key role in the field of agriculture by converting the unavailable form of nutrients present in soil, thereby increasing its assimilability for enhancing agricultural productivity. Rhizosphere bacteria have been found to dissolve K from insoluble K-bearing minerals [2–4]. Silicate bacteria can be applied as biofertilizers to fulfil the need of K from insoluble minerals [5]. There are certain bacteria which are capable of decomposing aluminosilicate minerals, releasing a portion of the K contained therein which could be further used in agriculture [6]. Bacteria also release a range of exoproducts, e.g., exopoly- mers and low-molecular-weight organic acids, with the poten- tial to interact with cations, some of which have the specific purpose of acquiring nutrients for the organism, e.g., sidero- phores which are released by some bacteria when they experi- ence iron deficiency. Potassium-solubilizing bacteria are capable of solubilizing rock K, mineral powder such as mica, illite, and orthoclase through production and excretion of organic acids [7]. Potassi- um occurs in the form of silicate minerals viz., muscovite, orthoclase, biotite, feldspar, illite, mica, vermiculite, smectite, gluconate, nepheline syenite etc. [8]. Potassium deficiency occurs due to the cultivation of high-yielding crop varieties and hybrids because K decreases easily in soil due to crop uptake, runoff, leaching, and soil erosion [9]. Some bacteria are reported to release K from K-bearing min- erals, e.g., Pseudomonas sp., Burkholderia sp., Acidithiobacillus sp., Bacillus spp. but only Bacillus mucilaginosus and Bacillus edaphicus are described to have high activity in mobilizing K in accessible form in soils [10–12]. Potassium- and phosphate- solubilizing bacteria (KSB and PSB) are extensively used as bio- fertilizers in Korea and China since cultivated soils in these countries are deficient in soil-available K and P [13]. Their application can reduce the use of agrochemicals and effectively support crop production in an eco-friendly manner [14–21]. Microbial inoculants constitute an important component of integrated nutrient management that leads to sustainable agri- culture. The purpose of the present study was to screen some newly isolated halotolerant bacterial strains from different hab- Chem. Eng. Technol. 2016, 39, No. 9, 1645–1652 ª 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.cet-journal.com Pooja Bachani 2,3 Sourish Bhattacharya 1,3 Deepti Jain 2,3 Shailesh Kumar Patidar 2,3 Rajapitamahuni Soundarya 2,3 Sushma Rani Tirkey 2,3 Bablesh Ranawat 2,3 S. V. Vamsi Bharadwaj 2,3 Sandhya Mishra 2 1 Process Design and Engineering Cell, CSIR – Central Salt and Marine Chemicals Research Institute, Bhavnagar, India. 2 Discipline of Salt and Marine Chemicals, CSIR – Central Salt and Marine Chemicals Research Institute, Bhavnagar, India. 3 Academy of Scientific and Innovative Research (AcSIR), CSIR – Central Salt and Marine Chemicals Research Institute, Bhavnagar, India. – Correspondence: Dr. Sandhya Mishra (smishra@csmcri.org), Salt and Marine Chemicals, CSIR-Central Salt and Marine Chemicals Research In- stitute, G. B. Marg, Waghawadi Road, Bhavnagar 364002, Gujarat, India. Research Article 1645