Many fields, like drug discovery and development involving the nervous system and neuronal signaling, have benefited from its extensive usage in locating protein information. Fig. 6.2 describes the various applications of MD. The ability to catabolize such compounds, which at the same time may have antibiotic properties towards other microorganisms, has an obvious competitive advantage for those specific bacteria capable of utilizing them.ĭue to the rapid development of supercomputers and the ability to deliver findings in a short period of time, this type of simulation has grown in relevance during the last 2–3 decades. Furthermore, neither organism could utilize the unnatural, synthetic enantiomer, (−)-calystegine B 2. 54 In addition, wild-type Rhizobium meliloti 41 was capable of using natural (+)-calystegine B 2 ( 16, R 1 = α-OH, R 2 = α-OH) as an exclusive source of carbon and nitrogen, whereas a catabolism-deficient strain of R. Over 20% of the bacteria isolated from the rhizospheres of calystegine-producing plants were capable of catabolizing the alkaloids, whereas no bacteria with this ability were obtained from plants which did not elaborate calystegines. ![]() 34 Although these alkaloids have now been detected in other plant parts, there appears to be a relatively high abundance in subterranean organs of the Convolvulaceae and Solanaceae and they are therefore believed to be nutritional mediators between such plants and associated rhizosphere bacteria. The calystegines were first isolated from roots of the bindweed, Calystegia sepium. 66 The antibiotic activity of the same alkaloid towards Xanthomonas oryzae renders it capable of preventing the bacterial leaf blight of rice. lavandulae against a drug-resistant strain of Shigella flexneri. There has been little information reported in regard to the effect of polyhydroxy alkaloid inhibitors on growth or function of microorganisms, although nojirimycin ( 6, R 1 = α-OH, R 2 = α-OH) was discovered as a result of the antimicrobial activity of Streptomyces nojiriencis, S. Molyneux, in Comprehensive Natural Products Chemistry, 1999 3.07.4.4 Antimicrobial Activity The main control measures are use of disease-free or treated seed and crop rotation.Īlan D. Bacteria overwinter on the seed and in crop residue and are spread by rain, direct contact, and insects. The diseases develop mainly in rainy, damp weather. Small lesions form on the kernels as well. 12-14C and 12-14D) they also retard spike elongation and cause blighting. Severe infections cause leaves to turn yellow and die from the tip downward ( Figs. Droplets of white exudate are common on the stripes. The symptoms appear on leaf blades and sheaths as small, linear, water-soaked areas that soon elongate and coalesce into irregular, narrow, yellowish, or brownish stripes ( Fig. ![]() Most such diseases only occasionally cause reduction in yields, but some are of major importance. ![]() They cause more or less similar diseases on one or more of the cereals and grasses. Most bacterial leaf spots and blights of cereals are probably worldwide in distribution. oryzae and (D) bacterial leaf streak caused by X. ![]() (C) Bacterial blight of rice caused by X. Longitudinal lesions on leaves (A) and reddish-black lesions on glumes (B) of wheat infected with the wheat streak and black chaff bacterium Xanthomonas campestris pv.
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