RESUMEN
Microbial isolate Z143-1 found to be associated with an unidentified tunicate was characterized due to its significant antimicrobial activity. Z143-1 is similar to Pseudovibrio ascidiaceicola and Pseudovibrio denitrificans in morphological, physiological and biochemical characteristics, except for its ability to ferment glucose and produce a characteristic red pigment. Fatty acid methyl ester analysis revealed a predominance of the fatty acid 18:1 omega7c at 80.55%, at levels slightly lower than the Pseudovibrio denitrificans type strain DN34(T) (87.7%). The mol% G+C of Z143-1 is 54.02, relatively higher than the Pseudovibrio denitrificans type strain DN34(T) and Pseudovibrio ascidiaceicola with mol% G+C of 51.7 and 51.4, respectively. However, phylogenetic analysis of the 16S rRNA gene sequence of Z143-1 showed 100% similarity with the Pseudovibrio denitrificans type strain DN34(T). In this study, the bacterium Z143-1 is reported as a new strain of Pseudovibrio denitrificans. While there is no report of a secondary metabolite for Pseudovibrio denitrificans, Z143-1 produces the red pigment heptylprodigiosin, also known as 16-methyl-15-heptyl-prodiginine, which shows anti-Staphylococcus aureus activity.
Asunto(s)
Prodigiosina/análogos & derivados , Rhodobacteraceae/clasificación , Rhodobacteraceae/aislamiento & purificación , Urocordados/microbiología , Animales , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Ácidos Grasos/análisis , Genes de ARNr , Glucosa/metabolismo , Datos de Secuencia Molecular , Filipinas , Filogenia , Pigmentos Biológicos/biosíntesis , Prodigiosina/química , Prodigiosina/aislamiento & purificación , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Rhodobacteraceae/química , Rhodobacteraceae/genética , Análisis de Secuencia de ADN , Homología de Secuencia de Ácido NucleicoRESUMEN
We report here the existence of anaerobic nitrogen-fixing consortia (ANFICOs) consisting of N(2)-fixing clostridia and diverse nondiazotrophic bacteria in nonleguminous plants; we found these ANFICOs while attempting to overcome a problem with culturing nitrogen-fixing microbes from various gramineous plants. A major feature of ANFICOs is that N(2) fixation by the anaerobic clostridia is supported by the elimination of oxygen by the accompanying bacteria in the culture. In a few ANFICOs, nondiazotrophic bacteria specifically induced nitrogen fixation of the clostridia in culture. ANFICOs are widespread in wild rice species and pioneer plants, which are able to grow in unfavorable locations. These results indicate that clostridia are naturally occurring endophytes in gramineous plants and that clostridial N(2) fixation arises in association with nondiazotrophic endophytes.
Asunto(s)
Clostridium/crecimiento & desarrollo , Ecosistema , Fijación del Nitrógeno , Oryza/microbiología , Anaerobiosis , Betaproteobacteria/genética , Betaproteobacteria/crecimiento & desarrollo , Betaproteobacteria/metabolismo , Clostridium/genética , Clostridium/metabolismo , Medios de Cultivo , ADN Ribosómico/análisis , Gammaproteobacteria/genética , Gammaproteobacteria/crecimiento & desarrollo , Gammaproteobacteria/metabolismo , Bacterias Grampositivas/genética , Bacterias Grampositivas/crecimiento & desarrollo , Bacterias Grampositivas/metabolismo , Datos de Secuencia Molecular , Oxígeno/farmacología , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
A beta-glucoronidase (GUS)-marked strain of Herbaspirillum seropedicae Z67 was inoculated onto rice seedling cvs. IR42 and IR72. Internal populations peaked at over 10(6) log CFU per gram of fresh weight by 5 to 7 days after inoculation (DAI) but declined to 10(3) to 10(4) log CFU per gram of fresh weight by 28 DAI. GUS staining was most intense on coleoptiles, lateral roots, and at the junctions of some of the main and lateral roots. Bacteria entered the roots via cracks at the points of lateral root emergence, with cv. IR72 appearing to be more aggressively infected than cv. IR42. H. seropedicae subsequently colonized the root intercellular spaces, aerenchyma, and cortical cells, with a few penetrating the stele to enter the vascular tissue. Xylem vessels in leaves and stems were extensively colonized at 2 DAI but, in later harvests (7 and 13 DAI), a host defense reaction was often observed. Dense colonies of H. seropedicae with some bacteria expressing nitrogenase Fe-protein were seen within leaf and stem epidermal cells, intercellular spaces, and substomatal cavities up until 28 DAI. Epiphytic bacteria were also seen. Both varieties showed nitrogenase activity but only with added C, and the dry weights of the inoculated plants were significantly increased. Only cv. IR42 showed a significant (approximately 30%) increase in N content above that of the uninoculated controls, and it also incorporated a significant amount of 15N2.
