THE BEACH PLAQUE: An Ocean of Virus

Going for a swim can be fun, but for me? Hell no! Am not hydrophobic just that i fear large water coupled with the fact that all types of predators are there, down to even the smallest microscopic ones- the bacteria of course. I can imagine myself attacked by some shoal of fishes or sting by jellyfishes or infected by some bacteria. Don’t mind me, I’m just being paranoid. The fact is that i haven’t learnt how to swim. Besides, I can’t stop to imagine the micro-flora of the ocean including the ones pathogenic to human. Could they infect us and cause diseases?

They might, they might not; what is the possibility of viruses in the ocean?

Some microbiologists had before searched the marine habitats for the presence of viruses but no turn out so it was assumed the oceans probably did not contain many or any virus. But not anymore as recent discoveries have changed this view radically. These microbiologists of course in different groups centrifuged seawater at high speeds or passed it through an ultra-filter and then examined the sediment or suspension in an electron microscope.

They found out that marine viruses are about 10 times more populous than marine bacteria. Between 1million and 1billion virus particles per milliliter are present at the ocean’s surface. It has been estimated that the top one millimeter of the world’s oceans could contain a total of over 3 X 1030 virus particles. Although little detailed work has been done on marine viruses, it appears that many contain double-stranded DNA. Most are probably bacteriophages and can infect both marine heterotrophs and cyanobacteria. Up to 70% of marine prokaryotes may be infected by phages. Viruses that infect diatoms and other major algal components of the marine phytoplankton also have been detected.

Marine viruses may be very important ecologically. Viruses may control marine algal blooms such as red tides, and bacteriophages could account for one-third or more of the total aquatic bacterial mortality or turnover. If true, this is of major ecological significance because the reproduction of marine bacteria far exceeds marine protozoan grazing capacity. Virus lysis of prokaryotic and algal cells may well contribute greatly to carbon and nitrogen cycling in marine food webs. It could reduce the level of marine primary productivity in some situations.

Bacteriophages also may greatly accelerate the flow of genes between marine bacteria. Virus-induced bacterial lysis could generate most of the free DNA present in seawater. Gene transfer between aquatic bacteria by transformation does occur, and bacterial lysis by phages would increase its probability. Furthermore, such high phage concentrations can stimulate gene exchange by transduction. These genetic exchanges could have both positive and negative consequences. Genes that enable marine bacteria to degrade toxic pollutants such as those in oil spills could spread through the native population. On the other hand, antibiotic resistance genes in bacteria from raw sewage released into the ocean also might be dispersed.

So anytime I’m at the beach, I stay put on the beach and just enjoy the view of the never ending ocean tides.


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