Psychrophilic and psychrotrophic microorganisms

Gounot, Anne-Monique

doi:10.1007/bf01946390

Cited by 134 publications

(57 citation statements)

References 38 publications

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“…According to Gounot (1986) psychrophilic or psychotropic microorganisms can grow at cold temperatures although they have a maximum growth temperature near or above 20°C. As a consequence, we can suppose that during the trial the epiphytic bacteria able to grow at low temperature, although their optimal growth temperature is much more higher (25°C), were counted.…”

Section: Microbiological Analysismentioning

confidence: 99%

Marketability of ready-to-eat cactus pear as affected by temperature and modified atmosphere

2011

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In order to increase the diffusion of cactus pear fruits, in this study, the proper maturity index for peeling and processing them as ready-to-eat product was evaluated and characterized. Thereafter, the effects of different storage temperatures and modified atmosphere conditions on the marketability of ready-to-eat cactus pear were studied. The storage of ready-to-eat fruits at 4°C in both passive (air) and semi-active (10 kPa O 2 and 10 kPa CO 2 ) modified atmosphere improved the marketability by 30%, whereas the storage at 8°C caused a dangerous reduction in O 2 partial pressure inside modified atmosphere packages, due to fruits' increased metabolic activity. A very low level of initial microbial growth was detected, while a severe increase in mesophilic and psychrophilic bacteria was shown in control samples at both temperatures during storage; an inhibitory effect of modified atmosphere on microbial growth was also observed. In conclusion, modified atmosphere improved only the marketability of fruits stored at 4°C; whereas the storage at 8°C resulted in deleterious effects on the ready-toeat fruits, whether stored in air or in modified atmosphere.

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Section: Microbiological Analysismentioning

confidence: 99%

Marketability of ready-to-eat cactus pear as affected by temperature and modified atmosphere

2011

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“…Deinococcus is a remarkable bacterium in that it possesses the ability to withstand very high doses of ionizing radiation; it was originally isolated from cans of meat irradiated for sterilization (14). It has been posited that since there are virtually no terrestrial environments that generate radiation doses intolerable to this organism, this ability must have been selected for as a by-product of other DNA damage mechanisms.…”

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confidence: 99%

“…Furthermore, psychrophilic microorganisms have made several adaptations to life at cold temperatures. For some, soluble carbohydrates and polyols serve as cryoprotectants (21) and increased amounts of unsaturated fatty acids in membranes enhance their fluidity (14), and there are enzymes in psychrophils which are adapted to work at low temperatures (13).…”

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confidence: 99%

Bacterial Activity in South Pole Snow

Carpenter

Lin

Capone

2000

Appl Environ Microbiol

289

146

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Large populations (200 to 5,000 cells ml ؊1 in snowmelt) of bacteria were present in surface snow and firn from the south pole sampled in January 1999 and 2000. DNA isolated from this snow yielded ribosomal DNA sequences similar to those of several psychrophilic bacteria and a bacterium which aligns closely with members of the genus Deinococcus, an ionizing-radiation-and desiccation-resistant genus. We also obtained evidence of low rates of bacterial DNA and protein synthesis which indicates that the organisms were metabolizing at ambient subzero temperatures (؊12 to ؊17°C).There are no reports which document active metabolism of bacteria in the surface snow of the interior of the Antarctic continent. At the south pole, temperatures are extreme and austral winter air temperatures reach about Ϫ85°C, while in summer it can warm to about Ϫ13°C (mean monthly air temperature in December is Ϫ26°C). Bacteria have previously been cultured from samples taken from Antarctic ice cores (1), and deep cores from the accreted ice above subglacial Lake Vostok revealed a high diversity (24) of species that were reported to be metabolically active when warmed to 3°C (16). We report here bacterial populations and associated metabolic activity in surface (upper 20 cm) snow and firn collected at the south pole in the austral summer.Sampling. Snow samples were collected on 9 and 18 January 1999 and 10 January 2000 at the Amundsen-Scott South Pole Station. Care was taken to sample at the edge of the Clean Sector of the National Oceanic and Atmospheric Administration Clean Air Laboratory upwind of the Station (grid 115 to 120), so that contaminating bacteria from the human habitat would not be collected. Snow was sampled using sterile procedures, and Snowpak containers, which hold ca. 60 to 80 liters of snow, were returned frozen to the Crary laboratory at McMurdo Station for analysis within 24 h of collection.Microscopy. Microbes were concentrated by filtering 20 to 50 ml of snowmelt onto a 0.02-m-pore-size Anodisc filter, and bacteria were stained with the DNA fluorescent dye SYBR green (22). Counts were done using a Zeiss Axioskop microscope at ϫ1,000. Scanning electron microscopy (SEM) was done on samples preserved in 4% glutaraldehyde-1.8% RNase-free sucrose-10 mM phosphate buffer (pH 7.4) and held at 1°C until processing for SEM.DNA sequencing. Melted snow (10 liters) from each snow sample was filtered through a 0.2-m-pore-size Nalgene filtration unit on a clean bench. The sample retained on the membrane was then subjected to DNA purification using cetyltrimethylammonium bromide and chloroform according to a procedure as modified in reference 8. Briefly, the membrane was incubated with 1 ml of Tris-EDTA buffer containing lysozyme (1 mg/ml) at 37°C for 1 h with constant shaking (250 rpm). Subsequently, NaCl and sodium dodecyl sulfate were added at final concentrations of 0.7 M and 1%, respectively, and the mixture was incubated at 70°C for 15 min (gently hand shaken every 5 min). Next, the mixture was incubated with 1 mg of RNase ...

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“…tures close to 0 °C and exhibit maximal growth rates Because the organisms grow under these condiin the range 10-12 °C (Gounot, 1991). There has tions, enzymes from psychrophiles clearly function been extensive interest in these organisms as agents at low temperature, and structural adaptation of of spoilage of milk and other refrigerated foodstuffs protein to cold activity might provide an insight into (Kumura, Mikawa & Saito, 1993) and as potential the molecular basis of psychrophily.…”

Section: Introductionmentioning

confidence: 99%

“…, ... i i r i, phihc growth to low temperatures are not fully Psychrophilic organisms are ahle to grow at tempera-understood (Gounot, 1991). tures close to 0 °C and exhibit maximal growth rates Because the organisms grow under these condiin the range 10-12 °C (Gounot, 1991).…”

Section: Introductionmentioning

confidence: 99%

Characterization of acid invertase from the snow mould Monographella nivalis: a mesophilic enzyme from a psychrophilic fungus

1995

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SUMMARYA soluble acid invertase was extracted by mechanical disruption of mycelium of the psychrophile Monographella nivalis grown on sucrose in submerged culture. The crude preparation was stable to incubation at pH 6-2 for 1 h at temperatures up to 47 °C and was stable to handling at room temperature. Half of the initial activity was lost after 1 h at 52 °C and all activity was lost after 1 h at 57 °C. A single isoform with activity against sucrose was detected on both native PAGE and lEF activity gels, exhibiting an isoelectric point of pH 3-6. The activity bound tightly to Concanavalin A-sepharose and was not displaced by 500 mM a-methyl mannopyranosidase indicating the enzyme to be a mannose-containing glycoprotein. By gel filtration, the apparent M^ was determined at 195 kDa. The invertase was purified 106-fold by salt precipitation. The partially purified enzyme exhibited maximal activity at pH 4-2 and apparent Michaelis constants for sucrose of 12, 20 and 2-6 mM at 3, 9 and 15 °C. The activity increased exponentially with temperature in the range 7-55 °C. £>," fell with increased temperature giving values of 1-96 between 5 and 15 °C and 1-60 between 40 and SO °C. Maximal activity was recorded at 55 °C. Arrhenius analysis of temperature data in the range 7-52 °C produced a continuous linear relationship. The activation energy for sucrose hydrolysis was 38-8 kj mol'. The thermal stability and thermal kinetic properties of the invertase were similar to those of invertases from mesophilic organisms. The invertase catalysed fructosyl transfer at 13 % of the molar activity against sucrose when assayed under conditions analogous to those in culture. The major fructan products were neokestose, isokestose, kestose and an unidentified tetrasaccharide. Traces of larger fructans were also detected. The transient accumulation of fructan in cultures of M. nivalis can be explained as a side reaction of invertase activity. The enzymological and physiological data do not suggest a cryoprotective function for fructan during the growth of the fungus.

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Psychrophilic and psychrotrophic microorganisms

Cited by 134 publications

References 38 publications

Marketability of ready-to-eat cactus pear as affected by temperature and modified atmosphere

Marketability of ready-to-eat cactus pear as affected by temperature and modified atmosphere

Bacterial Activity in South Pole Snow

Characterization of acid invertase from the snow mould Monographella nivalis: a mesophilic enzyme from a psychrophilic fungus

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