Peran bakteri endofit penghasil IAA

prosiding 01/2011;
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    ABSTRACT: Culture supernatant fluids of 50 phosphate-dissolving bacteria isolated from rhizospheres of crop plants were examined for IAA, gibberellins and cytokinins. These bacteria possessed phytase activity and 27 could dissolve rock phosphate. Twenty bacteria synthesized all 3 types of plant hormones, 43 produced IAA, 29 formed gibberellins and 45 cultures produced cytokinin-like substances. Of the 50 bacteria tested 28 decomposed IAA. Plant growth inhibitors were detected in cultures of some isolates. The ecological significance of these rhizosphere bacteria and their mode of action when used as inoculants is considered.
    The Journal of applied bacteriology 05/1976; 40(2):129-34. DOI:10.1111/j.1365-2672.1976.tb04161.x
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    ABSTRACT: The screening of antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, yeast and fungi was carried out on isopropanol extracts prepared from 121 isolates of endophytic fungi isolated from medicinal plants in Malaysia. Sensitivity was found to vary among the microorganisms. Bacillus subtilis, Saccharomyces cerevisiae and Alternaria sp. were susceptible to extracts from three, two and two isolates of endophytic fungi, respectively. None were found effective against Salmonella typhimurium. Sixteen endophytic fungal isolates tested were also found to exhibit antitumor activity in the yeast cell-based assay.
    Malaysian Journal of Medical Sciences 07/2002; 9(2):23-33.
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    ABSTRACT: Agriculturally important grasses such as sugar cane (Saccharum sp.), rice (Oryza sativa), wheat (Triticum aestivum) sorghum (Sorghum bicolor), maize (Zea mays), Panicum maxi-mum, Brachiaria spp., and Pennisetum purpureum contain numerous diazotrophic bacteria, such as, Acetobacter diazotrophicus, Herbaspirillum spp., Azospirillum spp. These bacteria do not usually cause disease symptoms in the plants with which they are associated and the more numerous of them, for example, Herbaspirillum spp. and A. diazotrophicus, are obligate or facultative endo-phytes that do not survive well (or at all) in native soil; these are thought to be spread from plant generation to plant generation via seeds, vegetative propagation, dead plant material, and possi-bly by insect sap feeders. By contrast, Azospirillum spp. are not wholly endophytic but are root-associated, soil-dwelling bacteria that are also often found within plants, probably entering host plants via seeds or via wounds/cracks at lateral root junctions. Endophytic diazotrophs have been isolated from a number of grasses in which significant biological N 2 fixation (BNF) has been demonstrated, particularly Brazilian sugar cane varieties, but also in rice, maize, and sorghum. However, although the endophytic diazotrophs are held to be the causative agents of the observed BNF, direct evidence for this is lacking. Therefore, in this review we examine probable sites of bacterial multiplication and/or BNF within endophyte-containing grasses and discuss these in terms of potential benefits (or not) to both host plants and bacteria. In particular, we examine how potentially large numbers of bacteria, especially Herbaspirillum spp., A. diazotrophicus, and Azo-spirillum spp., can exist extracellularly within non-specialized (for symbiotic purposes) regions such as xylem vessels and intercellular spaces. The processes of infection and colonization of various grasses (particularly sugar cane) by diazotrophic endophytes are also described, and these are compared with those of important (nondiazotrophic) endophytic sugar cane pathogens such as Clavibacter xyli subsp. xyli and Xanthomonas albilineans.
    Critical Reviews in Plant Sciences 01/1997; 50(17):77-119. DOI:10.1080/07352689891304195 · 5.44 Impact Factor