Bacteria: actinomycetes, 121 types

Like all bacteria, actinomycetes are prokaryotic microorganisms. In addition, the adenine-thymine and guanine-cytosine contents of bacteria and actinomycetes are similar, as are the cell wall constituents of both types of microorganisms. Actinomycetes filaments are also about the same size as those of bacteria. 

Compounds reported to have inhibitory effects on cyanobacteria have been isolated from a diverse range of organisms including terrestrial plants, aquatic plants, fungi, bacteria, actinomycetes, protozoa, and even from some species of green algae and cyanobacteria. The structural types... 

The amount and type of organic matter in soils plays a role in the extent to which a crop is affected by certain plant diseases. In some cases, organic matter may increase the incidence and severity of a disease but under proper management beneficial effects can usually be realized. This applies particularly to diseases produced by fungi but also to those caused by bacteria, actinomycetes and possibly viruses and nematodes. 

Detectable population changes in laboratory systems of bulk-soil and rhizosphere phenolic-acid utilizing microorganisms to phenolic acid enrichment are a function of a variety of soil physicochemical and biotic factors including type of phenolic acid, phenolic acid enrichment concentrations, presence of other available organic compounds, nuttition, soil type, and initial microbial populations. Responses of microbes to phenolic acids or phenolic acid mixtures also varied with the type of microbe (e.g bacteria, actinomycetes, or fungi). 

Like fungi, however, actinomycetes display extensive mycelial branching, and both types of microorganisms form aerial mycelia and conidia. Moreover, growth of actinomycetes in liquid culture tends to produce fungus-like clumps or pellets rather than the turbidity produced by bacteria. Finally, growth rates in fungi and actinomycetes are not exponential as they are in bacteria rather, they are cubic [35,42]. 

Acler Actiluatics. Other antibiotics were quickly discovered after the introduction of penicillin. A different type of antibiotic, streptomycin, which is active against a widei lange of pathogens than penicillin and is a potent inhibitor of Mycobacterium tuberculosis, was isolated from a strain of actinomycete from the throat of a chicken by Waksman at Rutgers in 1944 (Aiba and Evans). Actinomycetes are commonly found in soil and are intermediate between fungi and bacteria. Since 1944. numerous other metabolic products of actinomycetes have been isolated and have made a transition from the bench scale to wide therapeutic use. 

The factors that affect the ability of microorganisms to decompose organic material include type of organic material, temperature, pH, and redox potential (Eh). Fungi and actinomycetes are primarily responsible for the initial decomposition of organic waste. After that, bacteria are able to produce protease, a proteolytic enzyme which breaks protein down into simple compounds such as amino acids. The amino acids are absorbed by the microorganisms and ammonia is released by the following reactions ... 

From Table 1 it can be seen that the majority of naturally-occurring polyhydroxylated alkaloids have been isolated from plants. Although the first alkaloid of this type to be discovered (nojirimycin) was isolated from the fermentation broth of a species of Streptomyces, only a limited number of bacteria (principally actinomycetes)... 

Actinomycetes are filamentous bacteria that are often observed on stone surfaces and a large range of types has been isolated from stone. Like fungi, the filaments cause mechanical damage to stone by penetration and development of an extended web of hyphae in the stone (mycelium). These bacteria can produce patches of growth on stone particles and around stone pores, often interacting with salt crystals, which can further enhance the deteriogenic effects of salts. 

The polyketide synthesis chemically and biochemically resembles that of fatty acids. The reaction of fatty acid synthesis is inhibited by the fungal product ceru-lenin [9]. It inhibits all known types of fatty acid synthases, both multifunctional enzyme complex and unassociated enzyme from different sources like that of some bacteria, yeast, plants, and mammalians [10]. Cerulenin also blocks synthesis of polyketides in a wide variety of organisms, including actinomycetes, fungi, and plants [11, 12]. The inhibition of fatty acid synthesis by cerulenin is based on binding to the cysteine residue in the condensation reaction domain [13]. Synthesis of both polyketide and fatty acids is initiated by a Claisen condensation reaction between a starter carboxylic acid and a dicarboxylic acid such as malonic or methylmalonic acid. An example of this type of synthesis is shown in Fig. 1. An acetate and malonate as enzyme-linked thioesters are used as starter and extender, respectively. The starter unit is linked through a thioester linkage to the cysteine residue in the active site of the enzymatic unit, p-ketoacyl ACP synthase (KS), which catalyzes the condensation reaction. On the other hand, the extender... 

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