Microorganism eubacteria

Microorganisms can be classified into three domains eubacteria, archaea, and eukaryotes (fungi). The domain accounting for the most numerous representatives is the eubacteria. Figure 3.1. elucidates the connection between the three domains, which branched off very early in evolution, in all likelihood more than a billion years ago. 

The sulfur- and sulfate-reducing microorganisms represent a large and diverse group that is strictly anaerobic. Most are eubacteria, but several archaea that reduce sulfur have also been described. 

Enzymatic. Biological procedures for cholesterol removal make use of microorganisms that produce enzymes to convert cholesterol into innocuous compounds. Several enzymatic systems are being investigated in different cormtries of the world. Most systems use a cholesterol reductase that converts the cholesterol into coprostanol and coprosterol (52, 57). These converted compounds are very poorly absorbed by the digestive system and pass through intact. Several investigators have isolated and characterized Eubacteria able to convert cholesterol into coprostanol from rat, baboon, and human feces. Leaves of cucumber, soybeans, corn, and beans are known to contain similar enzymes (45, 57, 58). Lactobacillus acidophilus has also been reported to metabolize cholesterol (51). 

Bacterial polysaccharides can also serve as markers to identify specific bacterial species or genera. Typical microbial polysaccharides include peptidoglycans, lipopolysaccharides, and teichoic/teichuronic acids. Some markers such as muramic acid, D-alanine, and p-hydroxy myristic acid are present in the polysaccharides from eubacteria but are uncommon in higher life forms such as plants and animals. Pyrolysis results on bacterial polysaccharides were discussed in Sections 7.9 and 7.10. Specific pyrolysis products such as propionamide or peaks characteristic for KDO have been used for Py-MS or Py-GC/MS characterization of microorganisms. 

Some myxobacteria kill eubacteria and other microorganisms with a secreted antibiotic, lyse the dead cells with an extracellular enzyme mixture and utilize the soluble products. 

In microorganisms, growth was generally inhibited at nickel concentrations in the medium of 1-5 mg/liter in the case of actinomycetes, yeast, and marine and nonmarine eubacteria and at levels of 5-100 p.g/liter the growth of algae was reduced [35,36]. 

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