Characterestics of Marine Microorganisms

Characterestics of Marine Microorganisms

	Characterestics of Marine Microorganisms - Since the marine environment is characterized by environmental conditions which are entirely different from other environments, its microflora is also very much different from that of others. Marine microflora has its own special characteristics which enable it to survive in that environment. The main characteristic of marine flora is its capacity to survive and grow in sea/ocean.
Most of the bacterial flora in ocean are Gram-negative rods. The dominance of Gram-negative bacteria in aquatic environment is due to their cell structure. Aquatic environments are nutritionally dilute when compared with terrestrial environment. Under such conditions the outer membrane, especially the lipopolysaccharide (LPS), of Gram-negative bacteria helps to absorb nutrients. Various important hydrolytic enzymes are retained within the periplasmic space. Thus, the possible dilution of enzymes, which may occur when they are excreted out into the environment, is prevented. In addition LPS gives protection against toxic molecules like fatty acids and antibiotics. A larger proportion of the marine bacteria is motile and pigments producers.
Facultative aerobes dominate sea and there are relatively very few obligate aerobes and obligate anaerobes. When cultured most oceanic bacteria grow more slowly and form smaller colonies than those from other environments. Many of them are capable of proteolysis.
As with any other aquatic bacteria, marine bacteria can grow in extremely low concentrations of nutrients and hence are called oligotrophic bacteria. Generally, the concentration of organic matter in seawater will be less than mg per liter. Other interesting features of marine microorganisms are their ability to survive at very low temperature and at high salinity. The groups exhibiting the above characteristics are referred to as psychrophiles and halophiles respectively. Marine bacteria are also characterized by their pressure tolerance, especially those at depths. These forms belong to the group of barophiles.
	The generation time of marine bacteria is quite long, ranging from less than one hour to many months. The shortest generation time, 9.8 minutes, has been reported for Pseudomonas natriegens at 37°C. In marine environment, when freeliving bacteria are compared with attached bacteria the latter are bigger in size. This may be due to the fact that attached forms assimilate more dissolved organic matter than the free living forms

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