Isolation and Identification of Bacteria from Stored Soil Samples
Sajeda Saleh Yousef Nojoum
ساجدة صالح يوسف نجوم
Soil microbial population is large and diverse, and it is affected by biotic factors such as soil type and climate changes. Interaction of various amounts of water, sunlight, nutrients, temperature and acidity are important determinants of the numbers and types of microorganisms in specific portion of soil. Bacillus specie are ubiquitous in soils and are characterized with their ability to form endospores within cells that provides high resistance to desiccation, heat and chemicals. In this study, thirteen different types of stored soils were used to isolate and identify 16S rDNA of bacteria species that have survived for several years in plastic bags at room temperature using Universal Method based on utilizing the Golden Mixture7 (G7) which used from previous study. Different types of bacterial genera/species in stored soil samples were identified as; Lysinibacillus fusiformis strain WS1-3, Bacillus sp. (in: Bacteria) strain CM-CNRG 602, Peribacillus asahii strain OM18, Bacillus cereus strain BCd16, Bacillus cereus strain BHU4, Bacillus amyloliquefaciens strain CS13, Bacillus subtilis strain UIS0380, Lysinibacillus fusiformis strain P-R2A48, Bacillus cereus strain NCIM2157, Bacillus safensis strain MUGA119 with sequence similarities 98%. The presence of bacilli in stored soil samples and the rarity of other types of bacteria including Gram-negative bacteria indicated that spore formers bacteria may dominate since they resisted environmental stress and could persist for many years until suitable environment is available. Depending on results of this study, a numbers of Bacillus spp. were identified in different samples of soil which were stored for several years. This indicated that most common type of bacteria that can live in stored soils for long period of time are Bacillus Spp. The absence of less tolerant species in stored soils for years under aerobic condition may have resulted in the death of these species which are usually present in fresh soil samples while retaining the endospore-forming species.