Characteristics Of Microbial Organisms

a) Microbial “functions” can be used to refer to the traits of microbial organisms that is “associated to biogeochemical processes or ecosystem process under investigation” [1]. The term “functions” is usually attached to the activities of microbes that are deemed important to humans and that they have no meaning to the microbes which require these “functions” for survival.

In the marine environment, some functions include primary production, decomposition and nutrient cycling. Primary production is important as they help to fix energy from different sources. Photoautotrophs use sunlight while chemoautotrophs use inorganic electron donors like hydrogen sulphide (H2S) to produce complex organic compounds that heterotrophs can consume directly

These interactions can be competitive, mutualistic (beneficial to both), antagonistic (one killing or inhibiting another), facilitative (one helping the other with no benefit to itself) or neutral. Some bacteria can be pathogenic (note pathogenicity can be a function), causing diseases and harming the hosts that they colonize and the hosts can respond by producing chemicals to inhibit or kill them, e.g. halogenated furanones of Delisea pulchra. Predators of bacteria are also important for the maintenance of bacterial communities. There are bacteriophages in both marine environments and wastewater treatment reactors. If a population of bacteria increases drastically perhaps due to an influx of nutrients, then bacteriophages that specifically target that population of bacteria will start attacking and killing their hosts, thereby causing a decrease in the population. However, after some time, when the bacterial population is very low, the phage population will also start decreasing rapidly due to the lack of hosts/prey. This allows bacteria population numbers to start increasing again back to their original before the influx of nutrients. Hence, bacteriophages can maintain bacterial population numbers in the different communities. Some hosts like corals and sponges provide protection to their microbes. In the case for corals, the interaction is mutualistic as the zooxanthellae that they protect provide complex substrates that the corals use for growth. Hence, hosts can provide a selection pressure for or against (in the case of Delisea pulchra) some microbes, ultimately affecting the bacterial communities and functions present. Similarly, while some microbes can produce toxins to kill other microbes, some require other microbes to survive. In biofilms, aerobic bacteria survive on the top while anaerobes