Salt requirements for membrane transport and solute retention in some moderate halophiles

MacLeod, Robert A.

doi:10.1111/j.1574-6968.1986.tb01850.x

Cited by 17 publications

(6 citation statements)

References 26 publications

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“…Also, he said (p. 17) it may well be "that there are bacteria that are uniquely marine because they are able to survive and grow in the sea and we have yet to find out why." In a more positive conclusion to a different paper (MacLeod 1986), he suggested that the sodium-dependent transport processes may permit faster growth than do other types of transport processes. This ability has selective advantages when predators are present and may explain why marine bacteria often have a sodium dependency.…”

Section: Sodium Requirementmentioning

confidence: 95%

“…A soecology based on the physiology of microbes dium/proton antiporter maintains a downin the laboratory. This path has led to idenhill gradient of sodium into the cell tification of many of the forms present, a (MacLeod 1986). Additional studies by detailed knowledge of the physiology of MacLeod (summarized by MacLeod 1985) many forms, and from this an understandand others (Datta and MacQuillan 1987) ing of the various steps that occur in the show similar sodium dependence for a vacycles of elements and of organic matter in riety of organisms for every metabolite lakes, rivers, and oceans.…”

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confidence: 98%

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A comparison of the ecology of planktonic bacteria in fresh and salt water

Hobbie

1988

Limnology & Oceanography

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The planktonic bacteria inhabiting fresh and salt waters are not physiologically identical; most marine bacteria, for example, require sodium and some marine forms can thrive at 1,000 atm of pressure in the deep sea. Despite this difference, the conclusion of this review is that the ecology of planktonic bacteria is virtually identical in fresh and salt waters.The differences are small and mostly a matter of relative proportion of various processes. That is, similar bacterial processes occur in fresh and salt waters but in each environment, one process may be more important than another. For example, bacteria in freshwaters are exposed to high amounts of refractory dissolved organic carbon from soil and stream runoff, while many marine bacteria are exposed to relatively more of the labile organic matter from decaying algae. Also, under anaerobic conditions the sulfur cycle will be dominant in the sea while the carbon-methane cycle will be more important in freshwaters. In spite of the presence of relatively high amounts of methane in the sea, there is thus far little evidence that ,a significant amount of methane is being oxidized.Not enough is yet known to determine if there are dilfcrences in the grazing of bacteria in the two systems. Small, flagellated protozoans are very important grazers in freshwater and marine systems but there is some evidence from salt waters that ciliates are also important grazers. Marine ecosystems also contain large animals that can filter out bacteria. Sponges are the dominant suspension feeders on coral reefs, mussels and oysters are dominant in estuarine and marsh systems, and a large appendicularian may filter significant amounts of bacteria through a mucous net. Ecological understanding of the aquatic bacteria has advanced rapidly in the past two decades. One reason is the basic similarity between microbial ecology in fresh and salt waters and the consequent interchangeability of techniques.

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Section: Sodium Requirementmentioning

confidence: 95%

mentioning

confidence: 98%

A comparison of the ecology of planktonic bacteria in fresh and salt water

Hobbie

1988

Limnology & Oceanography

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“…On the other hand, the irreplaceable minimum requirement of NaCl (or similar salts) for growth also point to a specific role for NaCl (or one of its ions). Macleod (1986) has identified an osmotic function of NaCl for the retention of accumulated solutes in the moderate halophile Alteromonas haloplanktis, and in V. costicola, although sucrose was not investigated. It seems likely that different cellular functions will respond differently to ionic and non-ionic solutes in various halophiles.…”

Section: Discussionmentioning

confidence: 99%

The Role of Osmotic Effects in Haloadaptation of Vibrio costicola

Adams¹,

Bygraves²,

Kogut³

et al. 1987

Microbiology

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Growth rates of Vibrio costicola showed a broad optimum between 0.8 and 1.5 M-NaCl, and there was no growth above 3.3 M-NaCl in a peptone-based medium. The minimum requirement of 0.5 M-NaCl for growth in NaCl alone was reduced to 0.3 M-NaCl when the total solute concentration was raised to 0.5 to 1.0 M equivalent with sucrose or glycerol. Compared with equivalent NaCl concentrations, higher concentrations of sucrose were more inhibitory to growth, whereas glycerol had less effect. Increasing the medium NaCl concentration suddenly by 2- or 3-fold with either a constant starting, or final, salt concentration showed that, after the shift-up, the lag in growth, the rate of growth, and the inhibition of phospholipid synthesis depended both on the final NaCl concentration and the magnitude of the shift in salinity. The time-courses of phospholipid synthesis following a 2- or 3-fold shift-up in NaCl or sucrose media were very similar and exhibited a relative increase in phosphatidylglycerol synthesis over that of phosphatidylethanolamine. This 'switch-over' was not seen following shift-up in glycerol media when there was also a stimulation, rather than inhibition, of phospholipid synthesis. It is concluded that during phenotypic haloadaptation of V. costicola, osmotic effects play a significant part in the sensing of and response to raised external salinity.

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“…The problem of Na+-dependence in halophilic and marine bacteria is being dealt with in detail by MacLeod elsewhere in this issue [33]. Suffice it to say that in several such organisms, including V. costicola, with which we have been especially concerned, there seems to be a Na+/H + antiport and probably a symport between Na ÷ ions and a number of substrates, including a-aminoisobutyric acid (AIB), which is widely studied as an amino acid analogue.…”

Section: Studies Of Active Transportmentioning

confidence: 99%