Effect of an Alcaligenes faecalis inoculant strain on bacterial communities in flooded soil microcosms planted with rice seedlings

Lin, Mingzhi; Smalla, Kornelia; Heuer, Holger; Elsas, Jan Dirk van

doi:10.1016/s0929-1393(00)00097-4

Cited by 24 publications

(16 citation statements)

References 30 publications

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“…To follow the fate of inoculant strains in the rhizosphere of crop plants and nontarget plants, cultivation-dependent methods are most frequently applied. Most suitable for tracking inoculants by selective plating is the use of rifampicin-resistant mutants (i.e., involving mutation of the ribosomal binding site) of the PGPR strains (Lin et al 2000;Lottmann et al 2000), as the background level of indigenous soil bacteria with resistance to rifampicin is low. In the past selective plating had been used primarily for strain confirmation; however, nowadays it is understood that these tools, although rapid and inexpensive, are not sufficiently reliable for inoculant strain confirmation since spontaneous mutants (e.g., antibiotic resistance) can readily occur.…”

Section: Microbiological Monitoring Methodsmentioning

confidence: 99%

Rhizosphere and Root Colonization by Bacterial Inoculants and Their Monitoring Methods: A Critical Area in PGPR Research

Ahmad

Husain²,

Ahmad³

2011

Microbes and Microbial Technology

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Roots serve a multitude of functions in plants including anchorage, acquisition of nutrients and water, and production of exudates with growth regulatory properties. The root-soil interface, or rhizosphere, is the site of greatest biological and chemical activity within the soil matrix. Plant growth-promoting rhizobacteria (PGPR) are known to influence plant health by controlling plant pathogens or via direct enhancement of plant development in the laboratory and in greenhouse experiments. Unfortunately, however, results in the field have been less consistent. The colonization of roots by inoculated bacteria is an important step in the interaction between beneficial bacteria and the host plant. However, colonization is a complex phenomenon influenced by many biotic and abiotic parameters, some of which are only now apparent. Monitoring fate and metabolic activity of microbial inoculants as well as their impact on rhizosphere and soil microbial communities are needed to guarantee safe and reliable application, independent of whether they are genetically modified or not. The first and most crucial prerequisite for effective use of PGPRs is that strain identity and activity are continuously confirmed. A combination of both classical and molecular techniques must be perfected for more effective monitoring of inoculants strain (both genetically modified and unmodified) after release into the soil. Recent developments in techniques for studying rhizobacterial communities and detection and tracking systems of inoculated bacteria are important in future application and assessment of effectiveness and consistent performance of microbial inoculants in crop production and protection.

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Section: Microbiological Monitoring Methodsmentioning

confidence: 99%

Rhizosphere and Root Colonization by Bacterial Inoculants and Their Monitoring Methods: A Critical Area in PGPR Research

Ahmad

Husain²,

Ahmad³

2011

Microbes and Microbial Technology

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“…Oryza sativa L. japonica Zhongzao 9037 grown in Flevo silt loam soil in microcosms, Wageningen, The Netherlands (Lin et al, 2000).…”

Section: Methodsmentioning

confidence: 99%

The complete nucleotide sequence and environmental distribution of the cryptic, conjugative, broad-host-range plasmid pIPO2 isolated from bacteria of the wheat rhizosphere The GenBank accession number for the pIPO2T sequence reported in this paper is AJ297913.

et al. 2002

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Plasmid pIPO2 is a cryptic, conjugative, broad-host-range plasmid isolated from the wheat rhizosphere. It efficiently self-transfers between α, β and γ Proteobacteria and has a mobilizing/retromobilizing capacity for IncQ plasmids. The complete nucleotide sequence of pIPO2 is presented on the basis of its mini-Tn5 ::luxABtet-tagged derivative, pIPO2T. The pIPO2 sequence is 39 815 bp long and contains at least 43 complete ORFs. Apart from a suite of ORFs with unknown function, all of the genes carried on pIPO2 are predicted to be involved in plasmid replication, maintenance and conjugative transfer. The overall organization of these genes is different from previously described plasmids, but is similar to the genetic organization seen in pSB102, a conjugative plasmid recently isolated from the bacterial community of the alfalfa rhizosphere. The putative conjugative transfer region of pIPO2 covers 23 kb and contains the genes required for DNA processing (Dtr) and mating pair formation (Mpf). The organization of these transfer genes in pIPO2 is highly similar to the genetic organization seen in the environmental plasmid pSB102 and in pXF51 from the plant pathogen Xylella fastidiosa. Plasmids pSB102 and pXF51 have recently been proposed to form a new family of environmental broad-host-range plasmids. Here it is suggested that pIPO2 is a new member of this family. The proposed Mpf system of pIPO2 shares high amino acid sequence similarity with equivalent VirB proteins from the type IV secretion system of Brucella spp. Sequence information was used to design primers specific for the detection of pIPO2. Environmental DNA from a range of diverse habitats was screened by PCR with these primers. Consistently positive signals for the presence of pIPO2 were obtained from a range of soil-related habitats, including the rhizospheres of young wheat plants, of field-grown oats and of grass (all gramineous plants), as well as from the rhizosphere of tomato plants. These data add to the growing evidence that plasmids carry advantageous genes with as yet undefined functions in plant-associated communities.

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“…It is now established that several strains of Pseudomonas stutzeri can fix nitrogen (Vermeiren et al, 1999;Rediers et al, 2004). P. stutzeri A1501, isolated from rice, fixes nitrogen in the free-living state, under microaerobic conditions in media devoid of ammonia (You et al, 1991;Lin et al, 2000;Desnoues et al, 2003). A 30 kb DNA region containing the nitrogen fixation (nif and rnf) genes has been previously characterized and the regulatory nifLA region mapped within the main nif cluster.…”

Section: Introductionmentioning

confidence: 99%

Interaction between NifL and NifA in the nitrogen-fixing Pseudomonas stutzeri A1501

et al. 2006

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Pseudomonas stutzeri strain A1501 isolated from rice fixes nitrogen under microaerobic conditions in the free-living state. This paper describes the properties of nifL and nifA mutants as well as the physical interaction between NifL and NifA proteins. A nifL mutant strain that carried a mutation nonpolar on nifA expression retained nitrogenase activity. Complementation with a plasmid containing only nifL led to a decrease in nitrogenase activity in both the wild-type and the nifL mutant, suggesting that NifL acts as an antiactivator of NifA activity. Using the yeast two-hybrid system and purified protein domains of NifA and NifL, an interaction was shown between the C-terminal domain of NifL and the central domain of NifA, suggesting that NifL antiactivator activity is mediated by direct protein interaction with NifA.

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Effect of an Alcaligenes faecalis inoculant strain on bacterial communities in flooded soil microcosms planted with rice seedlings

Cited by 24 publications

References 30 publications

Rhizosphere and Root Colonization by Bacterial Inoculants and Their Monitoring Methods: A Critical Area in PGPR Research

Rhizosphere and Root Colonization by Bacterial Inoculants and Their Monitoring Methods: A Critical Area in PGPR Research

The complete nucleotide sequence and environmental distribution of the cryptic, conjugative, broad-host-range plasmid pIPO2 isolated from bacteria of the wheat rhizosphere The GenBank accession number for the pIPO2T sequence reported in this paper is AJ297913.

Interaction between NifL and NifA in the nitrogen-fixing Pseudomonas stutzeri A1501

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