Examination and Comparison of Microbial Diversity in Field-Scale Sewage Sludge Composters

Abstract

While the earth’s biodiversity has been studied in detail, to date, microbes have been completely omitted from meta-analytical studies of biodiversity data sets (Balmford & Bond, 2005; Diaz et al., 2006). In fact, biodiversity data sets are far from being considered a comprehensive global resource (Collen et al., 2008). Since the origin of prokaryotes on Earth over 3.5 billion years ago, the extent of evolutionary diversification within this group has been truly immense (DeLong & Pace, 2001; Payne et al., 2009). Microbial communities play important biological roles, such as the global cyclical change of materials in various environments (Diaz et al., 2006). As a result, existing biodiversity includes a vast and largely undiscovered diversity of microbes, which are probably very important for the sustainability of ecosystems (Swift et al., 2004). Hence, detailed investigation to characterize the global biodiversity of microbes is a very important task. Microbes have always formed a major component of global biodiversity, either as producers (e.g., phototrophic blue-green algae) or decomposers (e.g., heterotrophic bacteria) (Naeem et al., 2000). Furthermore, in the future, they may serve as producers of useful alternative energy sources (Ohnishi et al., 2010). For example, phototrophic microorganisms use the energy from light for the production of biomass, which is an energy source stored in all living organisms. In fact, microbial decomposers are used in industry to convert microbial biomass and organic waste materials, such as domestic garbage, into biofuels, such as methane, ethanol, and hydrogen (Swift et al., 2004; Kayhanian et al., 2007). Microbes are also used for bioremediation, which is the cleanup of pollution caused by human activities (Jorgensen et al., 2000). In this process, various microbes have been isolated from nature, which are capable of degrading spilled oil, solvents, and other environmentally toxic pollutants. Furthermore, the breadth of microbial diversity on Earth provides genetic resources that offer solutions for environmental and energy issues, and research in this area is currently expanding. Considering the serious environmental and energy issues that humans face today, a better understanding of the ecophysiology of environmental microbes is warranted to address problems such as resource depletion and environmental pollution.