Oligotrophic bacteria

Organisms assigned to the genus Cycloclasticus have been isolated from a number of geographical locations and display a considerable metabolic versatility as follows  

Bacteria isolated from marine macrofaunal burrow sediments and assigned to Lutibac-terium anuloederans were able to degrade phenanthrene in a heavily contaminated sediment (Chung and King 2001). 

Marine roseobacters that contain bacteriochlorophyll a have been described (Oz et al. 2005), and the bacteriochlorophyll a-containing marine bacterium Porphyrobacter sanguineus was able to degrade biphenyl and dibenzofuran, though unable to use them as sole substrates for growth (Hiraishi et al. 2002). 

The roseobacters Silicibacter pomeroyi and Roseovarius nubinhibens were able to carry out the degradation of dimethylsulfoniopropionate to dimethylsulfide, and to methanethiol (Gonzalez et al. 2003), and are discussed further in Chapter 11, Part 2. 

It is experimentally difficult to obtain numerical estimates of the total number of bacteria present in seawater, and the contribution of ultramicroorganisms that have a small cell volume and low concentrations of DNA may be seriously underestimated. Although it is possible to evaluate their contribution to the uptake and mineralization of readily degraded compounds such as amino acids and carbohydrates, it is more difficult to estimate then-potential for degrading xenobiotics at realistic concentrations. 

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There is an indeterminacy in the term oligotroph, and the dilemma is exacerbated by the fact that it may be impossible to isolate obligate oligotrophs by established procedures. The application of DNA probes should, however, contribute to an understanding of the role of these noncultivable organisms. Oligotrophic bacteria in the marine environment are able to utilize low substrate concentrations, and they may be important in pristine environments. 

Kamagata Y, RR Fulthorpe, K Tamura, H Takami, LJ Forney, JM Tiedje (1997) Pristine environments harbor a new group of oligotrophic 2,4-dichlorophenoxyacetic acid-degrading bacteria. Appl Environ Microbiol 63 2266-2272. 

Martin P, RA MacLeod (1984) Observations on the distinction between oligotrophic and eutrophic marine bacteria. Appl Environ Microbiol 47 1017-1022. 

Tranvik, L. J. 1988a. Availability of dissolved organic carbon for planktonic bacteria in oligotrophic lakes of differing humic content. Microbial Ecology 16 311-322. 

Boetius, A., and K. Lochte. 1996. High proteolytic activities of deep-sea bacteria from oligotrophic polar sediments. Archiv fur Hydrobiologie 48 269—276. 

Marshall, K. C. (1988). Adhesion and growth of bacteria at surfaces in oligotrophic habitats. Canadian Journal of Microbiology, 34, 593-606. 

Figure 7.1 Classical and current views of the N cycle in the surface waters of oligotrophic oceans. The composition of the dissolved N pool is shown with approximate relative concentrations of inorganic and organic constituents indicated hy the sizes of the boxes. Dashed lines indicate transformations and processes included in the newer view of N cycling. (A) Some phytoplankton use simple and more complex organic compounds as a source of N and phytoplankton can he sources of inorganic and organic N as well. (B) There are multiple species of phytoplankton (cyanobacteria) in the open ocean that fix N2. (C) Bacteria compete for NOs and NH4+. (D) Bacteria can take up and excrete urea and also be a source of DON. (E) Some oceanic bacterioplankton appear to fix N2 (modified from Zehr and Ward, 2002).

Sass H., Cypionka H., and Babenzien H. D. (1997) Vertical distribution of sulfate-reducing bacteria at the oxic-anoxic interface in sediments of the oligotrophic Lake StechUn. FEMS Microbiol. Ecol. 22, 245-255. 

Sass H., Wieringa E., Cypionka H., Babenzien H. D., and Overmann J. (1998) High genetic and physiological diversity of sulfate-reducing bacteria isolated from an oligotrophic lake sediment. Arch. Microbiol. 170, 243—251. 

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