Physiological and morphological responses of the soil bacterium Rhodococcus opacus strain PD630 to water stress

Alvarez, Héctor M.; Silva, Roxana A.; Cesari, Ana C; Zamit, Ana L.; Peressutti, Silvia R.; Reichelt, Rudolf; Keller, Ulrike; Malkus, Ursula; Rasch, Coen R. N.; Maskow, Thomas; Mayer, Frank; Steinbüchel, Alexander

doi:10.1016/j.femsec.2004.06.002

Cited by 96 publications

(59 citation statements)

References 46 publications

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“…The increase in number of microbial cells is consistent with the reported increase in microbial biomass in a California grassland over the dry summer (Parker and Schimel, 2011). This is also consistent with previous work showing bacterial cell division and down-sizing in response to desiccation as well as starvation (Potts, 1994;Alvarez et al, 2004).…”

Section: Bacterial and Fungal Community-level Responsesupporting

confidence: 91%

Responses of soil bacterial and fungal communities to extreme desiccation and rewetting

2013

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The microbial response to summer desiccation reflects adaptation strategies, setting the stage for a large rainfall-induced soil CO 2 pulse upon rewetting, an important component of the ecosystem carbon budget. In three California annual grasslands, the present (DNA-based) and potentially active (RNA-based) soil bacterial and fungal communities were tracked over a summer season and in response to controlled rewetting of intact soil cores. Phylogenetic marker genes for bacterial (16S) and fungal (28S) RNA and DNA were sequenced, and the abundances of these genes and transcripts were measured. Although bacterial community composition differed among sites, all sites shared a similar response pattern of the present and potentially active bacterial community to dry-down and wet-up. In contrast, the fungal community was not detectably different among sites, and was largely unaffected by dry-down, showing marked resistance to dessication. The potentially active bacterial community changed significantly as summer dry-down progressed, then returned to pre-dry-down composition within several hours of rewetting, displaying spectacular resilience. Upon rewetting, transcript copies of bacterial rpoB genes increased consistently, reflecting rapid activity resumption. Acidobacteria and Actinobacteria were the most abundant phyla present and potentially active, and showed the largest changes in relative abundance. The relative increase (Actinobacteria) and decrease (Acidobacteria) with dry-down, and the reverse responses to rewetting reflected a differential response, which was conserved at the phylum level and consistent across sites. These contrasting desiccation-related bacterial life-strategies suggest that predicted changes in precipitation patterns may affect soil nutrient and carbon cycling by differentially impacting activity patterns of microbial communities.

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Section: Bacterial and Fungal Community-level Responsesupporting

confidence: 91%

Responses of soil bacterial and fungal communities to extreme desiccation and rewetting

2013

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“…Physiological studies analysing the accumulation and mobilization of storage lipids in Rhodococcus sp. showed that TAGs serve as a depot for carbon and energy in these bacteria (Alvarez et al, 2000(Alvarez et al, , 2004Alvarez & Steinbüchel, 2002). Strain PD630 can be considered as an oleaginous micro-organism, since TAGs can account for up to 76 or 87 % of the cellular dry weight in gluconate-or olive-oil-grown cells, respectively (Alvarez et al, 1996;Voss & Steinbüchel, 2001).…”

Section: Introductionmentioning

confidence: 99%

Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleaginous bacterium Rhodococcus opacus PD630

et al. 2008

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The oleaginous bacterium Rhodococus opacus strain PD630 serves as a model organism to investigate the metabolism of storage triacylglycerols (TAGs) in bacteria. The key enzyme catalysing the last step of TAG biosynthesis in bacteria is a promiscuous acyltransferase (Atf), exhibiting acyl-CoA acyltransferase activity to both diacylglycerols (DGAT activity) and fatty alcohols (wax ester synthase, WS activity). An 800 bp PCR product was obtained from chromosomal DNA of strain PD630 by using degenerate primers designed from conserved stretches of Atf proteins of Acinetobacter baylyi strain ADP1 and Mycobacterium smegmatis mc 2 155. The atf fragment was used as a probe on a strain PD630 gene library, resulting in the identification of a 3948 bp chromosomal DNA fragment containing the complete atf1 gene. An atf1 disruption mutant of strain PD630 exhibited a TAG-leaky phenotype and accumulated up to 50 % less fatty acids than the wild-type, with significantly reduced oleic acid content when cultivated in the presence of gluconate or oleic acid. Whereas DGAT activity was drastically reduced in comparison to the wild-type, WS activity remained almost unchanged in the mutant.RT-PCR analysis of gluconate-grown cells of strain PD630 showed that there is expression of atf1 under conditions of TAG synthesis. To identify additional Atfs in strain PD630, PCR employing non-degenerate primers deduced from Rhodococcus jostii RHA1 sequence data was used. This yielded nine additional atf-homologous genes exhibiting 88-99 % sequence identity to the corresponding strain RHA1 enzymes. Besides Atf1 only Atf2 exhibited high DGAT and/or WS activity when heterologously expressed in Escherichia coli.

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“…Members of the actinomycetes, particularly Streptomyces and Rhodococcus, reportedly accumulate lipid inclusion bodies during the stationary phase of growth (Alvarez & Steinbuchel, 2002). Bacteria have been shown to use these stored substances as a sole source of carbon and energy during prolonged starvation (Alvarez & Steinbuchel, 2002;Alvarez et al, 2004). Inclusion bodies were also present in the 7-month-old SAA cells, and the rod cells measured 0.5-0.85 mm60.45 mm in size (Fig.…”

Section: Tem Observations Of Saamentioning

confidence: 94%

Formation of specialized aerial architectures by Rhodococcus during utilization of vaporized p-cresol

et al. 2009

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When grown with vaporized alkylphenols such as p-cresol as the sole carbon and energy source, several isolated Rhodococcus strains formed growth structures like miniature mushrooms, termed here specialized aerial architectures (SAA), that reached sizes of up to 0.8 mm in height. Microscopic examination allowed us to view the distinct developmental stages during the formation of SAA from a selected strain, Rhodococcus sp. KL96. Initially, mounds consisting of long rod cells arose from a lawn of cells, and then highly branched structures were formed from the mounds. During the secondary stage of development, branching began after long rod cells grew outward and twisted longitudinally, serving as growth points, and the cells at the base of the mound became short rods that supported upward growth. Cells in the highly fluffy structures were eventually converted, via reductive division, into structures that resembled cocci, with a diameter of approximately 0.5 mm, that were arranged in chains. Most cells inside the SAA underwent a phase variation in order to form wrinkled colonies from cells that originally formed smooth colonies. Approximately 2 months was needed for complete development of the SAA, and viable cells were recovered from SAA that were incubated for more than a year. An extracellular polymeric matrix layer and lipid bodies appeared to play an important role in structural integrity and as a metabolic energy source, respectively. To our knowledge, similar formation of aerial structures for the purpose of substrate utilization has not been reported previously for Grampositive bacteria.

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Physiological and morphological responses of the soil bacterium Rhodococcus opacus strain PD630 to water stress

Cited by 96 publications

References 46 publications

Responses of soil bacterial and fungal communities to extreme desiccation and rewetting

Responses of soil bacterial and fungal communities to extreme desiccation and rewetting

Cloning and characterization of a gene involved in triacylglycerol biosynthesis and identification of additional homologous genes in the oleaginous bacterium Rhodococcus opacus PD630

Formation of specialized aerial architectures by Rhodococcus during utilization of vaporized p-cresol

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