Role of trehalose in heat and desiccation tolerance in the soil bacterium Rhizobium etli

Abstract

BackgroundThe compatible solute trehalose is involved in the osmostress response of Rhizobium etli, the microsymbiont of Phaseolus vulgaris. In this work, we reconstructed trehalose metabolism in R. etli, and investigated its role in cellular adaptation and survival to heat and desiccation stress under free living conditions.ResultsBesides trehalose as major compatible solute, R. etli CE3 also accumulated glutamate and, if present in the medium, mannitol. Putative genes for trehalose synthesis (otsAB/treS/treZY), uptake (aglEFGK/thuEFGK) and degradation (thuAB/treC) were scattered among the chromosome and plasmids p42a, p42c, p42e, and p42f, and in some instances found redundant. Two copies of the otsA gene, encoding trehalose-6-P-synthase, were located in the chromosome (otsAch) and plasmid p42a (otsAa), and the latter seemed to be acquired by horizontal transfer. High temperature alone did not influence growth of R. etli, but a combination of high temperature and osmotic stress was more deleterious for growth than osmotic stress alone. Although high temperature induced some trehalose synthesis by R. etli, trehalose biosynthesis was mainly triggered by osmotic stress. However, an otsAch mutant, unable to synthesize trehalose in minimal medium, showed impaired growth at high temperature, suggesting that trehalose plays a role in thermoprotection of R. etli. Desiccation tolerance by R. etli wild type cells was dependent of high trehalose production by osmotic pre-conditioned cells. Cells of the mutant strain otsAch showed ca. 3-fold lower survival levels than the wild type strain after drying, and a null viability after 4 days storage.ConclusionsOur findings suggest a beneficial effect of osmotic stress in R. etli tolerance to desiccation, and an important role of trehalose on the response of R. etli to high temperature and desiccation stress.

Comparative genomic analysis provides insights into the evolution and niche adaptation of marine Magnetospira sp. QH‐2 strain

“…The large number of enzymes involved in the release of glucose from glycogen found in QH‐2 genome (families GH13 and GH57) would help generate more glucose for trehalose synthesis, which is not the case in freshwater species. Because trehalose is a well‐known osmoprotectant (Reina‐Bueno et al ., ), the multiple trehalose synthesis pathways found in the QH‐2 genome imply the adaptation of this magnetotactic spirillum strain to the marine habitats.…”

Increased trehalose biosynthesis improves Mesorhizobium ciceri growth and symbiosis establishment in saline conditions

“…The role of trehalose in protecting rhizobia from various abiotic stresses, including salinity, has been reported for several species. Trehalose is essential for survival of R. etli at supraoptimal temperatures and drought stress (Reina-Bueno et al 2012). Accumulated trehalose plays an important role in protecting R. leguminosarum bv trifolii cells against desiccation stress (Mc Intyre et al 2007).…”

Thermal Resistance and Gene Expression of both Desiccation-Adapted and Rehydrated Salmonella enterica Serovar Typhimurium Cells in Aged Broiler Litter

“…The trehalose content was measured by using an enzymatic colorimetric assay by converting trehalose to glucose with trehalase and then determining the glucose content (45,46). Briefly, 50 l of the extract was incubated with 150 l of 0.2 mol liter Ϫ1 sodium acetate buffer (pH 5.5) and 50 l of 0.3 U ml Ϫ1 trehalase at 37°C for 6 h. The trehalose content was calculated from the amount of liberated glucose, which was quantified by using a glucose assay kit (Abnova Corporation, Taipei, Taiwan).…”