Similarity in Several Properties of Psychrophilic Bacteria Grown at Low and Moderate Temperatures

This review gives an overview about the structural organisation of different evolutionary lines of all enzymes capable of efficient dismutation of hydrogen peroxide. Major potential applications in biotechnology and clinical medicine justify further investigations. According to structural and functional similarities catalases can be divided in three subgroups. Typical catalases are homotetrameric haem proteins. The three-dimensional structure of six representatives has been resolved to atomic resolution. The central core of each subunit reveals a characteristic "catalase fold", extremely well conserved among this group. In the native tetramer structure pairs of subunits tightly interact via exchange of their N-terminal arms. This pseudo-knot structures implies a highly ordered assembly pathway. A minor subgroup ("large catalases") possesses an extra flavodoxin-like C-terminal domain. A > or = 25 A long channel leads from the enzyme surface to the deeply buried active site. It enables rapid and selective diffusion of the substrates to the active center. In several catalases NADPH is tightly bound close to the surface. This cofactor may prevent and reverse the formation of compound II, an inactive reaction intermediate. Bifunctional catalase-peroxidase are haem proteins which probably arose via gene duplication of an ancestral peroxidase gene. No detailed structural information is currently available. Even less is know about manganese catalases. Their di-manganese reaction centers may be evolutionary.

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Understanding the structure and function of catalases: clues from molecular evolution and in vitro mutagenesis

Zámocký

Koller

1999

Progress in Biophysics and Molecular Biology

315

203

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Hexosamine Production by Psychrotrophic Food‐spoilage Bacteria Under Varying Growth Conditions

Burke

Jay

Shelef

1977

Journal of Food Quality

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ABSTRACT. Four psychrotrophic, gram negative meat isolates were grown at 6 and 22°C with and without aeration, in AOAC synthetic broth with 0.1% glucose and in a basal medium containing 0.1% glucose and 0.5% glycine (BMGG‐1). In AOAC broth, three strains produced more hexosamine at 6°C, while the fourth produced more at 22°C. Three of the four strains also produced more slime at 6°C. All four strains grew faster with aeration at both temperatures, but produced less hexosamine. Under all conditions, the growth rate of each strain was inversely proportional to its hexosamine production. During the growth cycle in BMGG‐1, medium pH dropped until the log phase was under way and then rose again through the stationary phase. This rise coincided with the depletion of glucose. Hexosamine production first became detectable at the end of the log phase, rose during the stationary phase, and then leveled off. Adjusting pH to prevent the initial drop increased both growth and hexosamine production. Raising the concentration of glucose to 0.5% accelerated growth but decreased hexosamine production. Approximately 95.1% of the hexosamine produced was cell‐associated. It consisted primarily of glucosamine polymers with a lesser amount of galactosamine. Only 3.0% of the nitrogen from the BMGG‐1 was utilized by the cells. Of this 3.0%, 58% was used for ammonia, 27.2% for hexosamine, and 14.8% for other substances. Of the 40.7% used for total cell production, 63.8% went into hexosamine.

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Bacterial Growth in the Cold: Evidence for an Enhanced Substrate Requirement

Wiebe

Sheldon

Pomeroy

1992

Appl Environ Microbiol

166

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Growth responses and biovolume changes for four facultatively psychrophilic bacterial isolates from Conception Bay, Newfoundland, and the Arctic Ocean were examined at temperatures from-1.5 to 35°C, with substrate concentrations of 0.15, 1.5, and 1,500 mg of proteose peptone-yeast extract per liter. For two cultures, growth in 0.1, 1.0, and 1,000 mg of proline per liter was also examined. At 10 to 15°C and above, growth rates showed no marked effect of substrate concentration, while at-1.5 and 0°C, there was an increasing requirement for organic nutrients, with generation times in low-nutrient media that were two to three times longer than in high-nutrient media. Biovolume showed a clear dependence on substrate concentration and quality; the largest cells were in the highest-nutrient media. Biovolume was also affected by temperature; the largest cells were found at the lowest temperatures. These data have implications for both food web structure and carbon flow in cold waters and-for the effects of global climate change, since the change in growth rate is most dramatic at the lowest temperatures.

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Similarity in Several Properties of Psychrophilic Bacteria Grown at Low and Moderate Temperatures

Cited by 7 publications

References 17 publications

Understanding the structure and function of catalases: clues from molecular evolution and in vitro mutagenesis

Understanding the structure and function of catalases: clues from molecular evolution and in vitro mutagenesis

Hexosamine Production by Psychrotrophic Food‐spoilage Bacteria Under Varying Growth Conditions

Bacterial Growth in the Cold: Evidence for an Enhanced Substrate Requirement

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