VOL. 8, NO. 6, JUNE 2013 ISSN 1990-6145 ARPN Journal of Agricultural and Biological Science © 2006-2013 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 457 CHARACTERIZATION AND SELECTION OF HALOPHILIC MICROORGANISMS ISOLATED FROM MEXICAN SOILS Delgado-García M. 1 , De la Garza-Rodríguez I. 2 , Cruz Hernández M. A. 3 , Balagurusamy N. 4 , Aguilar C. 1 And Rodríguez-Herrera R. 1 1 Department of Food Research, School of Chemistry, Universidad Autónoma de Coahuila, Blvd. Venustiano Carranza, Saltillo, Coahuila, Mexico 2 Department of Analytical Chemistry, School of Chemistry, Universidad Autónoma de Coahuila, Blvd. Venustiano Carranza, Saltillo, Coahuila, Mexico 3 Applied Microbiology Center, GreenCorp Biorganiks de Mexico SA de CV., Saltillo, Coahuila, México 4 School of Biology, Universidad Autónoma de Coahuila, Mexico E-Mail: raul.rodriguez@uadec.edu.mx ABSTRACT Halophilic microorganisms thrive in conditions of high salt concentration and osmotic stress. Due to these reasons, halophilic microorganisms with ability to fix nitrogen or mobilize phosphate represent a potential as bio-fertilizer to increase crop growth and yield in saline soils. In this study, 35 different halophilic bacteria were isolated from saline soils of Coahuila State, Mexico. These bacterial isolates were characterized, and evaluated for their halophilic potential by growth kinetics, hydrolysis halos formation and in vitro sodium capture. Based on the results, seven potential strains for saline conditions were selected and were identified by 16S rDNA sequencing analysis Phylogenetic relationship of the selected strains as well as with other halophilic microorganisms was determined. Six of the identified strains were Halobacillus trueperi, Bacillus licheniformis, Bacillus pumilus, Staphylococcus succinus, Bacillus atrophaeus and Bacillus subtilis. Other two strains were identified Halobacillus sp. and Oceanobacillus sp., moderately halophilic organisms. Keywords: saline soils, 16S rDNA, bacillus spp., halobacillus spp., oceanobacillus sp., staphylococcu succinus. INTRODUCTION Worldwide around 897 million of hectares of surface area is affected by salinity. In Mexico, 10% of the irrigated area is affected due to high salt concentrations, and 64% of such saline soils are located in the Northern region [1]. In soils of arid and semiarid regions, the problem of excess salts is mainly due to evaporation and water pressure. In addition, salinity is a problem in areas with prolonged periods of drought, under dry climate zones and in coastal areas [2]. This is mainly due to weathering of mineral and surface of rock crusts, and in the process get deposited in groundwater resulting in saline groundwater [3]. Salinity in soils is also due to other causes such as excessive use of chemical fertilizers, poor quality of water used for irrigation, deforestation or intensive cultivation [2]. It is indisputable that high salt concentrations in soils strongly affect vegetative growth [4] since high salt concentrations prevent adequate absorption of nutrients by roots. Besides, high salt content in soil generates crusts which cause root asphyxia. In addition, the existence of sodium ion causes dispersion of organic matter and clays, modifying soil structure [3]. Soil salinity also affects microorganisms. However, halophilic microorganisms have capacity to tolerate and live under high salt concentrations by generating a balance inside and outside of the cell to avoid osmotic stress [5]. Further, accumulation of compatible solutes in cytoplasm such as glycine-betaine, sugar derivate like sucrose or trehalose and/ or inorganic ions such as sodium, potassium and chloride act as stabilizers of biologic structures [6, 7]. These traits of halophilic microorganism generate a great interest to the scientific community due to their potential applications in the biotechnological industries [8, 9, 10, 11, 12]. Enzymes of halophilic microorganisms have advantage over their non- halophilic counterparts due to their ability to maintain their stability and catalytic properties at high salt concentrations [13, 14, 15]. Additionally, the halobacteria are reported to produce bacteriorrhodopsin, bioplastics, and various enzymes [16, 17] their potential applications in different areas. However, extracellular enzymes production by halophilic microorganisms has not yet been investigated in detail. It is generating lot of interest in recent years on extracellular enzymes like proteases, amylases, DNases, pullulanases and lipases produced by halophilic microorganisms [18]. Cuatrociénegas, Coahuila is known for its high level of soil salinity and presence of abundant genetic variety of endemic microorganisms. Various halophilic bacteria have been isolated from small lakes in Cuatro Ciénegas [19, 20, 21, 22]. However, the halophilic microorganisms present in the soils of this location and other areas with saline soils have been little studied [23, 24, 25]. The objective in this study was to isolate and characterize halophilic microorganisms from saline soils at different locations of the state of Coahuila, Mexico. MATERIALS AND METHODS Soils samples Twelve soil samples from different saline locations of Arteaga, Ramos Arizpe, Monclova, Lamadrid and Cuatro Ciénegas counties of Coahuila, México were recollected (Table-1). Each sample was taken from the