Hydrothermal vent sediments as a source of microbial communities adaptable for environmental biotechnology applications

Hydrothermal vent systems are a great source of microorganisms, including those classified as extremophiles, that could be exploited for biotechnological purposes in the environmental field. Deep and shallow hydrothermal vents have been studied in regards of their microbial communities, and the interactions of these microorganisms with the hydrothermal vents fluids composition, and the role that they play in the cycling of carbon, nitrogen, sulfur and metals. The research conducted on hydrothermal vent systems has also reported the physical and chemical characteristics of the vent fluids and sediments and to some extent, the possible applications of the microorganisms that inhabit these ecosystems in environmental biotechnology, pharmaceutical, and alimentary industries. Shallow hydrothermal vents are ecosystems easier to reach than deep hydrothermal vents, therefore, there is a growing interest in the development of applications for hydrothermal vent sediments, particularly for the biodegradation of pollutants and bioremediation of contaminated marine sites. Research has shown that the microbial diversity and richness in both, deep and shallow hydrothermal vents share several phyla of microorganisms at a large extent. On the other hand, disruption and pollution of the marine environments is a current problem that has prevailed due to natural and anthropogenic inputs. Some examples of frequent marine pollution are the presence of hydrocarbons and heavy metals, for which effective bioremediation technologies still need to be developed and implemented. An approach for the applications in environmental biotechnology of some of the microorganisms that inhabit the hydrothermal vent systems involves the ex situ culturing and kinetic characterization under specific conditions such as for example: exposure to toxic organic compounds or unusual concentrations of certain heavy metals. Ex situ approaches are useful for the development of engineered biological processes to biodegrade organic pollutants such as those found in contaminated wastewater streams. In situ approaches for the application of marine microorganisms in the bioremediation of marine environments or biodegradation of major marine pollutants are still facing technical difficulties to succeed in a long-term scenario, but there are some examples such as benthic or sedimentary cells, which are systems whose purpose is the bioremediation of marine polluted sites. In the present chapter, an approach for the utilization of microorganisms from shallow hydrothermal vent sediments in environmental biotechnology is presented. This approach consists of the ex situ culturing of these microorganisms in bioreactors to simultaneously biodegrade organic toxic compounds and remove organic matter. The detailed procedures, culturing conditions, results obtained and advantages of the suggested ex situ approach are presented and discussed for the different cases in which the microorganisms enriched from hydrothermal vent sediments have been evaluated in the biological processes ex situ. The present information is useful for the designing at large scale of systems in which microorganisms cultured from hydrothermal vent systems could be used as the main source of biological catalyst.