Desiccation responses and survival of Sinorhizobium meliloti USDA 1021 in relation to growth phase, temperature, chloride and sulfate availability

Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
Letters in Applied Microbiology (Impact Factor: 1.66). 03/2006; 42(2):172-8. DOI: 10.1111/j.1472-765X.2005.01808.x
Source: PubMed


To identify physical and physiological conditions that affect the survival of Sinorhizobium meliloti USDA 1021 during desiccation.
An assay was developed to study desiccation response of S. meliloti USDA 1021 over a range of environmental conditions. We determined the survival during desiccation in relation to (i) matrices and media, (ii) growth phase, (iii) temperature, and (iv) chloride and sulfate availability.
This study indicates that survival of S. meliloti USDA 1021 during desiccation is enhanced: (i) when cells were dried in the stationary phase, (ii) with increasing drying temperature at an optimum of 37 degrees C, and (iii) during an increase of chloride and sulfate, but not sodium or potassium availability. In addition, we resolved that the best matrix to test survival was nitrocellulose filters.
The identification of physical and physiological factors that determine the survival during desiccation of S. meliloti USDA 1021 may aid in (i) the strategic development of improved seed inocula, (ii) the isolation, and (iii) the development of rhizobial strains with improved ability to survive desiccation. Furthermore, this work may provide insights into the survival of rhizobia under drought conditions.

Download full-text


Available from: Jan A C Vriezen
  • Source
    • "Due to spore forming capability Bacillus is one of the most important genera among PGPR which help in the formation of stable bioinocluant. Various environmental factors generate stress that affects the activity or potential of the local micro-flora (Vriezen et al. 2006). Therefore, study of phosphate-solubilizing Bacillus under stress conditions from the rhizosphere is the key area to screen new strains that has immense potential to be used as bioinoculant in the agriculture. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In the present study, out of 264 phosphate (P) solubilizing Bacillus strains isolated from apple rhizosphere, only twelve isolates were found to be efficient (showed most of the plant growth promoting activity) which were further characterized at molecular level using 16S rDNA partial gene sequencing. Out of 12 isolates, MZPSB 207 was found to be most efficient P-solubilizing (864.71 μg/ml) isolate which also showed indole acetic acid production (51.83 μg/ml), siderophore production, ammonia production, antagonistic property (against Rhizoctonia solani and Fusarium oxysporum), hydrolytic enzymes productions (protease, chitinase and cellulase), 1-aminocyclopropane-1-carboxylate (ACC) deaminase production (7.7 μm αKB mg-1 h-1). The in-vitro seed germination assay showed that Bacillus (twelve isolates) inoculated seeds showed more seed germination and seedling vigor rate as compared to uninoculated control treatment. For the genetic diversity studies of efficient 12 strains, the polyphasic approach using 16S-rDNA, Repetitive element sequence (rep) based PCR (ERIC-PCR and BOX-PCR) were used. Based on 16S rDNA partial gene sequencing the isolated Bacillus genus was divide into four groups. First group (five isolates), second group (two isolates), third group (three isolates) and fourth group (two isolates) which showed close genetic relatedness to the B. subtilis, B. pumulis, B. megaterium and B. amyloliquefaciens, respectively. The rep PCR fingerprinting showed variability between and within the species. The large variability was showed by ERIC-PCR whereas some variability was showed by BOX-PCR. The results clearly showed that 16S rRNA gene sequencing is unable to discriminate the isolates at strain level. But rep-PCR fingerprinting is excellent tool to characterize and discriminate the strains at the genomic level.
    Full-text · Article · Jun 2014 · SpringerPlus
  • Source
    • "This difference in the behavior of the two bacterial species is not surprising because the optimal growth phase for desiccation survival has been found to be largely dependent on the micro-organism (Boumahdi et al., 1999). Nevertheless, stationary phase cells are generally more resistant to physical stresses such as drying (Mary et al., 1986; Vriezen et al., 2006). This is due to the stress response triggered by carbon starvation and exhaustion of available food sources (Morgan et al., 2006 "
    [Show abstract] [Hide abstract]
    ABSTRACT: This work deals with optimising the cell survival of rhizobacteria encapsulated in alginate beads filled with starch. Immobilisation of rhizobacteria was done by dripping alginate-starch solution mixed with rhizobacteria into a calcium solution. Beads were analysed based on matrix formulation, bacteria growth phase, osmoprotectants and nature of calcium solution. Maximum cell recovery was obtained on Raoultella terrigena grown in medium supplemented with trehalose and calcium gluconate as gelling agent. Furthermore, dried beads containing Azospirillum brasilense presented 76% of viable cells after one year of storage. The survival of rhizobacteria during the bioencapsulation process can be improved by incorporating starch on beads composition, varying the growth phase of cells and using trehalose in growth culture medium. This work provides a selection of appropriate methods to improve the surviving rate of encapsulated cells during their production and long-term storage (∼1 year at 4°C).
    Full-text · Article · Feb 2012 · Journal of Microencapsulation
  • Source
    • "Many conditions have been identified that affect the survival of agriculturally important Rhizobiaceae during desiccation (Vincent et al. 1962; Bushby and Marshall 1977 Some factors affecting the survival of root nodule bacteria on desiccation; van Rensburg and Strijdom 1980; Dye 1982; Salema et al 1982 Death of rhizobia on inoculated seed, 1982 Rupture of nodule bacteria on drying and rehydration; Kremer and Peterson 1983; Mary et al. 1985, 1986; Kosanke et al. 1992; Smith 1992; Chenu 1993; Boumahdi et al. 1999; Estrella et al. 2004; Kaci et al. 2005; Vriezen et al. 2006). These conditions include the intrageneric differences to cope with desiccation stress affecting survival (vanRensburg and Strijdom 1980; Mary et al. 1985, 1986; Trotman and Weaver 1995; Boumahdi et al. 1999; Sadowski and Graham 1998). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Sinorhizobium meliloti is a microorganism commercially used in the production of e.g. Medicago sativa seed inocula. Many inocula are powder-based and production includes a drying step. Although S. meliloti survives drying well, the quality of the inocula is reduced during this process. In this study we determined survival during desiccation of the commercial strains 102F84 and 102F85 as well as the model strain USDA1021. The survival of S. meliloti 1021 was estimated during nine weeks at 22% relative humidity. We found that after an initial rapid decline of colony forming units, the decline slowed to a steady 10-fold reduction in colony forming units every 22 days. In spite of the reduction in colony forming units, the fraction of the population identified as viable (42-54%) based on the Baclight live/dead stain did not change significantly over time. This change in the ability of viable cells to form colonies shows (i) an underestimation of the survival of rhizobial cells using plating methods, and that (ii) in a part of the population desiccation induces a Viable But Non Culturable (VBNC)-like state, which has not been reported before. Resuscitation attempts did not lead to a higher recovery of colony forming units indicating the VBNC state is stable under the conditions tested. This observation has important consequences for the use of rhizobia. Finding methods to resuscitate this fraction may increase the quality of powder-based seed inocula.
    Full-text · Article · Jan 2012 · AMB Express
Show more