Associated Bacteria

Various bacteria were combined with an axenic strain of the A race and their influence on B. braunii growth and hydrocarbons was examined 114-116). Most of the tested microorganisms exert a strong detrimental influence however Flavobacterium aquatile exerts large promoting effects, both on the total algal biomass and on hydrocarbon production, probably as a result of the release of stimulating substances in the culture medium. 

The influence of immobilization was examined following direct entrapment of whole cells of B. braunii in alginate gel and polyurethane foams adsorption on preformed foams was also employed 117-121). All these experiments were carried out using batch cultures of the A race. 

Direct entrapment of B. braunii in various polyurethane foams revealed high toxicity of most of the tested polymers and a complete loss of viability occurred in numerous cases. However, a few polymers appear to be less toxic and some cells can survive entrapment nevertheless these showed poor metabolic activity and a ca fivefold decrease in hydrocarbon production was noted relative to free cells. In sharp contrast, no toxicity was detected following immobilization through adsorption on preformed foam pieces. Furthermore the total biomass and hydrocarbon productivities then obtained from the immobilized cultures are similar to the high values typical of controls. 

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The processes of electron transport and oxidative phosphorylation are membrane-associated. Bacteria are the simplest life form, and bacterial cells typically consist of a single cellular compartment surrounded by a plasma membrane and a more rigid cell wall. In such a system, the conversion of energy from NADH and [FADHg] to the energy of ATP via electron transport and oxidative phosphorylation is carried out at (and across) the plasma membrane. In eukaryotic cells, electron transport and oxidative phosphorylation are localized in mitochondria, which are also the sites of TCA cycle activity and (as we shall see in Chapter 24) fatty acid oxidation. Mammalian cells contain from 800 to 2500 mitochondria other types of cells may have as few as one or two or as many as half a million mitochondria. Human erythrocytes, whose purpose is simply to transport oxygen to tissues, contain no mitochondria at all. The typical mitochondrion is about 0.5 0.3 microns in diameter and from 0.5 micron to several microns long its overall shape is sensitive to metabolic conditions in the cell. 

A study using resuspended river sediment (Marchesi et al. 1991) illustrated the important interdependence of substrate attachment to particulate matter and its biodegradability. Addition of sodium dodecyl sulfate that is degradable resulted in a relative increase in the number of particle-associated bacteria, whereas this was not observed with the nondegrad-able analogs such as sodium tetradecyl sulfate or sodium dodecane sulfonate. 

Holm, C. Jespersen, L. A flow-cytometric gram-staining technique for milk-associated bacteria. Appl. Environ. Microbiol. 2003, 69, 2857-2863. 

Ronkko, R. Pennanen, T. Smolander, A. Kitunen, V. Kortemaa, H. Haahtela, K. Quantification of Frankia strains and other root-associated bacteria in pure cultures and in the rhizosphere of axenic seedlings by high-performance liquid chromatography-based muramic acid assay. Appl. Environ. Microbiol. 1994, 60, 3672-3678. 

Table 13.1 Entomopathogenic nematodes and their symbiotically associated bacteria (Reproduced...

Attractive Compounds. Though the first report on the identification of a pheromone from a scarabaeid beetle dates back more than 30 years - phenol as an attractant for males of the gras grub beetle Costelytra zealandica [135] which turned out to be produced by beetle associated bacteria [136] - most of the pheromone structures known today have been elucidated during the last decade [3,137,138]. 

Field studies point in a similar direction field comparisons of peptide hydrolysis rates and amino acid turnover in coastal sediments showed that amino acid production could exceed uptake by a factor of approximately 8 (Pantoja and Lee, 1999). A comparison of potential enzyme activities and sedimentary amino acid and carbohydrate inventories in sediments from the Ross Sea also showed that potential hydrolysis rates on time scales of hours should in theory rapidly deplete sedimentary amino acid and carbohydrate inventories (Fabiano and Danovaro, 1998). In deep-sea sediments, Poremba (1995) also found that potential enzyme activities in theory could exceed total sedimentary carbon input by a factor of 200. Finally, Smith et al. s (1992) investigation of potential hydrolysis rates and amino acid uptake in marine snow demonstrated that the particle-associated bacteria were potentially producing amino acids far in excess of their own carbon demand. 

Karner, M., and G. J. Herndl. 1992. Extracellular enzymatic activity and secondary production in free-living and marine-snow-associated bacteria. Marine Biology 113 341-347. 

Pierson, L.S., Wood, D.W. and Beck von Bodman, S., Quorum sensing in plant-associated bacteria, in Cell-Cell Signaling Bacteria, Dunny, G.M. and Winans, S.C., Eds., ASM Press, Washington, D.C., 1999, 101. 

Rice, D.L., and Hanson, R.B. (1984) A kinetic model for detritus nitrogen role of the associated bacteria in nitrogen accumulation. Bull. Mar. Sci. 35, 326-340. 

Kannenberg, E.L., Reuhs, B.L., Forsberg, L.S., Carlson, R.W. Lipopolysaccharides, K-antigens Their structures, biosynthesis, and function. In Spaink, H.P., Kondorosi, A., Hooykaas, P.J.J (eds.), The Rhizobiaceae Molecular Biology of Model Plant-Associated Bacteria. Kluwer Academic Publishers, Dordrecht/Boston/London (1998), pp. 119-154. 

Kobayashi, M., Suzuki, T., Fujita, T, et al. 1995. Occurrence of enzymes involved in biosynthesis of indole-3-acetic acid from indole-3-acetonitrile in plant-associated bacteria. Agrobacterium and Rhizobium. Proceedings of the National Academy of Science USA, 92 714-8. 

Estimates of N2 fixation rates in the global ocean continue to rise as results emerge from studies with the main N2 fixer in the ocean Trichodesmium, the heterocystous endosymbiont Richelia, as well as more recently discovered N2 fixers including unicellular diazotrophic cyanobacteria and bacterioplankton (Capone et al, 1997 HanseU and Feely 2000 Karl et al, 1997 Lipschultz and Owens, 1996 Montoya et al., 2004 Zehr et al, 1998 and 2001). Trichodesmium is involved in N release directly, through release of amino acids, DON, and NH4 (reviewed in Table 8.2). Trichodesmium is also a source of NH4+ and DON as a result of remineralization by associated bacteria, sloppy feeding and excretion by grazers (SeUner, 1992 Sheridan et al, 2002). 

Mohamed, N. M., Tal, Y., and Hill, R. T. (2006). The role of sponge-associated bacteria in nitrogen fixation. 11th International Symposium on Microbial Ecology-ISME, Vienna, Austria, August 20-25. 

Rohwer, F., Seguritan, V., Azam, F., and Knowlton, N. (2002). Diversity and distribution of coral-associated bacteria. 243, 1-10. 

Taylor, M. W., Schupp, P. J., et al. (2004). Host specificity in marine sponge-associated bacteria, and potential implications for marine microbial diversity. Environ. Microbiol. 6, 121—130. 

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