Effect of heat stress on cell activity and cell morphology of the tropical rhizobium, Sinorhizobium arboris

• Published in: FEMS microbiology ecology Vol. 34; no. 3; pp. 267 - 278
• Main Authors: Räsänen, Leena A., Elväng, Annelie M., Jansson, Janet, Lindström, Kristina
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2001; Blackwell; Oxford University Press
• Subjects: 5-sulfofluorescein diacetate; 6-sulfofluorescein diacetate; Action of physical and chemical agents on bacteria; Agronomy. Soil science and plant productions; Bacteriology; Biochemistry and biology; Biological and medical sciences; Bioluminescence; Cell activity; Cell morphology; Chemical, physicochemical, biochemical and biological properties; Cytology; Ecology; Energy reserves; Enzymatic activity; Enzyme activity; Esterase; Fundamental and applied biological sciences. Psychology; Growth patterns; Heat stress; Heat tolerance; luciferase; Microbiology; Morphology; Phenotypes; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Physiological effects; Reserves; Sinorhizobium arboris; Soil science; Bioluminescence; Heat stress; Cell activity; Cell morphology; Microbial activity; Microorganism growth; Symbionte; Temperature; Thermal shock; Morphology; Bacteria; Environmental factor; Rhizobiaceae
• ISSN: 0168-6496; 1574-6941; 1574-6941
• DOI: 10.1111/j.1574-6941.2001.tb00777.x

Abstract The effect of heat stress on the growth, physiological state, cell activity and cell morphology of the tropical Sinorhizobium arboris strain HAMBI 2190 was studied. The cells were chromosomally tagged with the firefly luciferase gene, luc. Since the bioluminescence phenotype is dependent on cellular energy reserves it was used as an indicator of the metabolic status of the cell population under various heat conditions. Variations in the numbers and lengths of growth phases between individual cultures indicated that the growth pattern at 40°C was disturbed compared to growth at 37 or 28°C. In addition, the cell morphology was changed radically. The number of culturable cells and the luciferase activity declined when the cultures were incubated at 40°C. By contrast, under all conditions studied, the cells could be stained with 5-(and 6-)sulfofluorescein diacetate, indicating esterase activity. This demonstrated that although the culturability and cellular energy reserves decreased considerably during heat stress, a majority of the of S. arboris cell population maintained basal enzyme activity.