Environmental Factors That Affect The Growth And Survival Of Microorganisms ( Potts 1994 )
6331 WordsJul 6, 201526 Pages
Microorganisms have developed multiple direct and indirect mechanisms that protect them against the environmental stresses they encounter. One of the most severe and widespread problems facing crop production is the degradation of soil quality due to desiccation and salinity, and almost 40% of the world’s land surface is affected by salinity-related problems (Zahran 1999, Veron, 2006). Water, and its availability, is one of the most vital environmental factors to affect the growth and survival of microorganisms (Potts 1994).
Within the soil environment, indirect protection of cellular structures and contents can be provided by cell surface coating with clay minerals or close association with organic substances. Some bacteria (Bacillus spp. and Actinobacteria) form heat-resistant spores to withstand dry conditions and high temperatures, while other microorganisms encase individual cells or aggregates of cells with polymeric substances or slime layers to form an extensive exopolymeric matrix or biofilms. These outer structures enable them to adhere to inorganic (e.g. soil pore walls, water conduits, mineral surfaces) or organic (e.g. roots) surfaces to insulate the entire microbial community against effects of high temperature and the associated lack of available water (Jozefaciuk et al., 2006; Berendsen et al., 2012; Rolli et al., 2015). Despite the potential physiological and lifestyle adaptations to desiccation available to soil microorganisms, many microbes yield to heat