Role of a Fasciclin domain protein in photooxidative stress and flocculation in Azospirillum brasilense Sp7

2021 ◽  
pp. 103875
Author(s):  
Ashutosh Prakash Dubey ◽  
Parul Pandey ◽  
Shivangi Mishra ◽  
Parikshit Gupta ◽  
Anil Kumar Tripathi
AMB Express ◽  
2019 ◽  
Vol 9 (1) ◽  
Author(s):  
María de los Angeles Martínez-Martínez ◽  
Bertha González-Pedrajo ◽  
Georges Dreyfus ◽  
Lucía Soto-Urzúa ◽  
Luis Javier Martínez-Morales

Abstract Phasins are amphiphilic proteins involved in the regulation of the number and size of polyhydroxybutyrate (PHB) granules. The plant growth promoting bacterium Azospirillum brasilense Sp7 accumulates high quantities of bioplastic PHB as carbon and energy source. By analyzing the genome, we identified six genes that code for proteins with a Phasin_2 domain. To understand the role of A. brasilense Sp7 PhaP1 (PhaP1Abs) on PHB synthesis, the phaP1 gene (AMK58_RS17065) was deleted. The morphology of the PHB granules was analyzed by transmission electron microscopy (TEM) and the PHB produced was quantified under three different C:N ratios in cultures subjected to null or low-oxygen transfer. The results showed that PhaP1Abs is involved in PHB granules morphology and in controlling early biopolymer accumulation. Using RT-PCR it was found that phasin genes, except phaP4, are transcribed in accordance with the C:N ratio used for the growth of A. brasilense. phaP1, phaP2 and phaP3 genes were able to respond to the growth conditions tested. This study reports the first analysis of a phasin protein in A. brasilense Sp7.


2002 ◽  
Vol 68 (2) ◽  
pp. 985-988 ◽  
Author(s):  
Jun Sun ◽  
Anne Van Dommelen ◽  
Jan Van Impe ◽  
Jos Vanderleyden

ABSTRACT The role of three key nitrogen regulatory genes, glnB (encoding the PII protein), glnZ (encoding the Pz protein), and glnD (encoding the GlnD protein), in regulation of poly-3-hydroxybutyrate (PHB) biosynthesis by ammonia in Azospirillum brasilense Sp7 was investigated. It was observed that glnB glnZ and glnD mutants produce substantially higher amounts of PHB than the wild type produces during the active growth phase. glnB and glnZ mutants have PHB production phenotypes similar to that of the wild type. Our results indicate that the PII-Pz system is apparently involved in nitrogen-dependent regulation of PHB biosynthesis in A. brasilense Sp7.


Microbiology ◽  
2012 ◽  
Vol 158 (12) ◽  
pp. 2891-2902 ◽  
Author(s):  
Santosh Kumar ◽  
Ashutosh Kumar Rai ◽  
Mukti Nath Mishra ◽  
Mansi Shukla ◽  
Pradhyumna Kumar Singh ◽  
...  

1996 ◽  
Vol 42 (5) ◽  
pp. 467-478 ◽  
Author(s):  
Anne Milcamps ◽  
Anne Van Dommelen ◽  
John Stigter ◽  
Jos Vanderleyden ◽  
Frans J. de Bruijn

The rpoN (ntrA) gene (encoding sigma 54) of Azospirillum brasilense Sp7 was isolated by using conserved rpoN primers and the polymerase chain reaction, and its nucleotide sequence was determined. The deduced amino acid sequence of the RpoN protein was found to share a high degree of homology with other members of the sigma 54 family. Two additional open reading frames were found in the Azospirillum brasilense rpoN region, with significant similarity to equivalent regions surrounding the rpoN locus in other bacteria. An rpoN mutant of Azospirillum brasilense Sp7 was constructed by gene replacement and found to be defective in nitrogen fixation, nitrate assimilation, and ammonium uptake. Lack of ammonium uptake was also found in previously isolated Azospirillum brasilense ntrB and ntrC mutants, further supporting the role of the ntr system in this process. In addition, the rpoN mutant was found to be nonmotile, suggesting a role of RpoN in Azospirillum brasilense flagellar biosynthesis.Key words: Azospirillum brasilense, sigma factor, nitrogen fixation, ammonium assimilation, motility.


2019 ◽  
Vol 32 (7) ◽  
pp. 828-840 ◽  
Author(s):  
Vijay Shankar Singh ◽  
Prajna Tripathi ◽  
Parul Pandey ◽  
Durgesh Narain Singh ◽  
Basant Kumar Dubey ◽  
...  

Azospirillum brasilense is a plant growth–promoting bacterium that colonizes the roots of a large number of plants, including C3 and C4 grasses. Malate has been used as a preferred source of carbon for the enrichment and isolation Azospirillum spp., but the genes involved in their transport and utilization are not yet characterized. In this study, we investigated the role of the two types of dicarboxylate transporters (DctP and DctA) of A. brasilense in their ability to colonize and promote growth of the roots of a C4 grass. We found that DctP protein was distinctly upregulated in A. brasilense grown with malate as sole carbon source. Inactivation of dctP in A. brasilense led to a drastic reduction in its ability to grow on dicarboxylates and form cell aggregates. Inactivation of dctA, however, showed a marginal reduction in growth and flocculation. The growth and nitrogen fixation of a dctP and dctA double mutant of A. brasilense were severely compromised. We have shown here that DctPQM and DctA transporters play a major and a minor role in the transport of C4-dicarboxylates in A. brasilense, respectively. Studies on inoculation of the seedlings of a C4 grass, Eleusine corcana, with A. brasilense and its dicarboxylate transport mutants revealed that dicarboxylate transporters are required by A. brasilense for an efficient colonization of plant roots and their growth.


1991 ◽  
pp. 749-754
Author(s):  
Maria A. Vanoni ◽  
Giuliana Zanetti ◽  
Bruno Curti ◽  
Dale E. Edmondson

1992 ◽  
Vol 38 (10) ◽  
pp. 1042-1047 ◽  
Author(s):  
Christian Chauret ◽  
Wilfredo L. Barraquio ◽  
Roger Knowles

Nondenaturating disc gel electrophoresis revealed that 99Mo was incorporated into the nitrate reductase of Azospirillum brasilense grown in the absence but not in the presence of tungstate. Under denitrifying conditions, A. brasilense grown in tungsten-free medium steadily accumulated 99Mo for 12 h. In contrast, Paracoccus denitrificans grown under the same conditions ceased uptake after 1 h. However, both bacteria were incapable of accumulating significant amounts of 99Mo in media containing 10 mM tungstate, even though nitrate was reduced by A. brasilense. Aerobically grown A. brasilense cells transported 99Mo more efficiently than anaerobically grown cells. Key words: Azospirillum brasilense, tungsten, molybdenum incorporation, nitrate reduction.


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