Secretome of Microbiota in Extreme Conditions

Microorganisms are highly versatile living beings that have survived nearly 4 billion years of evolutionary change. Microbes have adapted to environmental conditions that range from cold to hot and from anoxic to oxic. Their life forms range from free living to symbiotic. During the harsh environment, bacteria adopt various strategies to acquire multiple systems so as to thrive against adverse conditions. Among them, secreted proteins play a major role and facilitate most of the interactions of the cells with their surrounding environment as well as with neighbouring cells. Bacterial cells secrete the proteins, metabolites and various molecules to the extracellular environments to sustain nutrient depletion conditions, adhesion on substrate (biofilm formation), invasion of host or antagonism, etc. These microbial functions are managed through their secretion system, which are very sophisticated molecular machines that include export/secretion of required proteins or metabolic factors required for the conjugation and survival processes. Hence, the present chapter is aimed to describe the microbes, specially bacteria adapted to survival in extreme temperature. Further, the chapter highlights the secretion system to understand how these bacteria deal with the extreme environments.