Microbial aggregates

Borrego, S., Nubio, E., Ancheta, O. and Espinosa, M. E. (2000). Study of the microbial aggregation in mycobacterium using image analysis and electron microscopy, Tissue Cell, 32, 494—500. 

Microbial aggregates used in hazardous waste treatment. Microorganisms are key biotechnology agents because of their diverse biodegradation and biotransformation abihties and their small size. They have high ratios of biomass surface to biomass volume, which ensure... 

Several forms of the modified Stake s law have been used in a series of studies concerning aggregates in the liquid phase (Li and Yuan, 2002). In these studies, the particle-liquid density difference has been further modified and adopted for the cases of impermeable bio-logical/microbial aggregates, permeable aggregates, and fractal aggregates. 

Biddanda, B. A. 1988. Microbial aggregation and degradation of phytoplankton-derived detritus in seawater. II. Microbial metabolism. Marine Ecology Progress Series 42 89-95. 

Figure 10 In situ identification of microbial aggregates consisting of Archea (red) in the center and SO -reducing bacteria (green) on the periphery. Microorganisms were labeled with rRNA-targeted oligio-nucleotide probes, (source Boetius et al., 2000b).

Fig. 8.7 Fluorescence in situ Hybridisation (FISH) overlay image of microbial aggregate involved in anaerobic methane oxidation. Different microbes were stained using different oligonucleotide probes. Core is ANNM-2 Archaea, surrounded by sulphate-reducing Desulfosarcina imaged by laser scanning confocal microscopy. From V.J. Orphan etal. in Proc. Natl. Acad. Set USA, Vol. 99, 7663—7668, 2002. Reproduced with permission. Copyright National Academy of Sciences (2002).

Extra cellular polymeric substances (EPS) produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids, and humic substances. EPS make up the intercellular space of microbial aggregates and form the structure and architecture of the biofilm matrix. The key functions of EPS are comprised of the mediation of the initial attachment of cells to different substrate, and protection against environmental stress and dehydration. The latter has a profound impact on an array of biomedical, biotechnical, and industrial fields including pharmaceutical and surgical applications, food engineering, bioremediation. 

Fractal dimensions of both bacteria and yeast fiocs have also been determined in liquid culture in the laboratory, providing a useful quantification of fluid dynamic environment effects upon microbial aggregates. The bacterium Zoogloea ramigera had a A = 1-69 0.11 (determined from projected area. Section 8.2.4)... 

Ngian KF, Lin SH. Diffusion coefficient of oxygen in microbial aggregates. Biotechnol Bio-eng 1976 18 1623. 

Sheng, G.-E, Yu, H.-Q. Li, X.-Y. (2010) Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems a review. Biotechnology Advances, 28, 882-894. 

FORSTER S.M. and NICOLSON T.H. 1981. Microbial aggregation of sand in a maritime dune succession. Soil Biology and Biochemistry, 13, 205-208. 

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