The marine group that is adding newly
discovered species at the fastest rate,
however, is the non-photo-
synthetic marine microbes. Species identification of
bacteria was limited to what could be
cultured in the laboratory until the
recent use of molecular-genetic techniques
for identifications [ DeLong et al.,
1989; Giovannoni and Cary, 1993].
Bacteria are very abundant in the ocean,
with concentrations of about a million
individuals per milliliter of water, and
yet only an estimated 1% can be
identified via culturing! Diversity
estimates and understanding of
phylogenetic relationships within the
marine bacteria have expanded remarkably
in just the last half-decade because of
molecular-genetic techniques [
Giovannoni et al., 1990; Ward et
al., 1990].
Phylogeny and nucleotide signature analyses of cloned ribosomal DNAs have, for example, elucidated entirely new groups of marine bacteria within the Archaebacteria Kingdom. In the ocean, this group of bacteria had been found only under extreme conditions, such as in anaerobic sediments, hydrothermal vents and unusually high salinity. But recently, two groups of researchers independently discovered high abundances of several new archaebacteria species in typical coastal marine environments [ DeLong, 1992; Fuhrman et al., 1992, 1993]. These new species represent a new physiological type within this Kingdom, and reside and presumably compete with aerobic, mesophilic bacteria in the Eubacteria Kingdom in marine coastal waters.
New knowledge of marine bacteria, combined with the discovery of the widespread existence and high abundances of marine viruses [ Bergh et al., 1989; Proctor and Fuhrman, 1990], has fundamentally altered concepts of marine microbial diversity and the role of microbes in global geochemical cycles. Furthermore, there are potential economic benefits of new knowledge of marine microbial diversity because of their demonstrated and potential uses in biomedical products [ Colwell, 1983; Fautin, 1988].