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Utilization of hypophosphite as the sole source of phosphorus
64
Microbial adaption to extreme environments
from the medium and was taken up or bound by the threads of this organism. Electronmicroscopic photographs showed that zinc was
adsorbed or embedded in the outer sheath of the wall.
SURJ?ACE ATTACK ON POLYETHYLENE BY AMUCOR
SPECIES
G. VAN DEN ENDE
From polyethylene film, which had been partly buried in” soil for four years, we isolated different bacteria and fungi. The bulk of the microorganlvms were separated from the homogenized plastic by shaking with water. A Mucor species was isolated and used for further experiments. New plastic strips were placed on nutrient agar in a petri dish and 3 ml of a spore suspension (2 X 1O6 spores/ cm3) of the Mucor was poured over the surface of the agar. After an incubation period of four months at 23°C the pl&tic was cleaned by rubbing tBe surface with 70% ethanol. A layer of technovit, a synthetic resin, was formed on the cleaned plastic surface. When
the technovit had hardened it was separated from the plastic, shadowed with platinum and strengthened with carbon. The technovit was dissolved in acetone and the surface layer of the platinum photographed by electron microscopy. Our interpretation of the pictures is as foiiows. Upon the surface we see threadlike structures, which can be imprints of hyphae or the hyphae themselves lying upon the plastic. Because the widths of the fungal hyphae were in average 11.2 pm and the traces on the plastic film have a width of 1.0-l .2 pm we believe that the structures on the plastic are imprints of the hyphae.
W. HEINEN
Bu&&&scardcllyiicuscan utilize phosphorus either as phosphate, pk~phite, or hypophosphibe. When cultures are supplied with PO, as the sole source of phosphorus, the hypophospnite is oxidized to phosphate, which accwtes in the medi d is theta metaboduring growth. g cell suspensions also have the ability to oxidize
The reaction is PC), is not ox whether the cells are grow medium. The hyp optim~ly between
Microbialadhption to extreme environments
65
monium sulfate fractionation of the cell-free extract showed that the PO, oxidation!, which is accompanied by the formation of NADH, requires at least three components: An ammonium sulfate fraction of the cell-free extract,
the residue fraction containing the respiratory chain, and NAD as cofactor. Most probably a second cofactor, as yet not characterized. is required to accomplish full activity.
6.D. VOGELS
One way in which microorganisms can oppose extreme conditions consists of a positive or negative tactic respotlse to a changing environment. Such a respor.se can be triggered by changes in temperature (thermotaxis) or in the chemical composition of the medium (chemotaxis). Adler ( 1966) and Mesibov and dler (1972) made excellent studies on the positive chemotaxis of E. co2i towards various nutrients, e.g. amino acids and sugars. rTtappeared that a tactic response is also observed towards certain chemicals which are not metabolized or even are not transported inward at all. Therefore, chemoreceptors, which recognize the compcunds, must be located in the ccl or cell membrane. These recepre quite specific, transfer the obtors, w served signal in such a way to the flagella that movement alters. oshland (1972) pointed out
that bacteria are too small to detect concentration differences over one body length in concentration gradients normally applied in studies on chemotaxis. They suggested that bacteria must be fitted with some kind of rudimentary memory. Such a memory combined with a ~dime~tary nerve system that is involved in the translation of chemoreception into alteration of the position of flagella enables the bacteria to fly away from extreme conditions to favourable ones.
eferences Adler, J., 1966, Chemotaxis in bacteria, Science 153, 708-716. Macnab, R.M. and D.E. Koshland, Jr., 1972, The gadientsensing mechanism in bacterial chemozaxis. &or. Natl. Acad. Sci. US 69,2509--2512. Mesibov, R. and J. Adler, 1972, Chemotaxis toward amino acids in E. coli, J. Racteriol. 112,315-326.
Microbial adaption to extreme environments
from the medium and was taken up or bound by the threads of this organism. Electronmicroscopic photographs showed that zinc was
adsorbed or embedded in the outer sheath of the wall.
SURJ?ACE ATTACK ON POLYETHYLENE BY AMUCOR
SPECIES
G. VAN DEN ENDE
From polyethylene film, which had been partly buried in” soil for four years, we isolated different bacteria and fungi. The bulk of the microorganlvms were separated from the homogenized plastic by shaking with water. A Mucor species was isolated and used for further experiments. New plastic strips were placed on nutrient agar in a petri dish and 3 ml of a spore suspension (2 X 1O6 spores/ cm3) of the Mucor was poured over the surface of the agar. After an incubation period of four months at 23°C the pl&tic was cleaned by rubbing tBe surface with 70% ethanol. A layer of technovit, a synthetic resin, was formed on the cleaned plastic surface. When
the technovit had hardened it was separated from the plastic, shadowed with platinum and strengthened with carbon. The technovit was dissolved in acetone and the surface layer of the platinum photographed by electron microscopy. Our interpretation of the pictures is as foiiows. Upon the surface we see threadlike structures, which can be imprints of hyphae or the hyphae themselves lying upon the plastic. Because the widths of the fungal hyphae were in average 11.2 pm and the traces on the plastic film have a width of 1.0-l .2 pm we believe that the structures on the plastic are imprints of the hyphae.
W. HEINEN
Bu&&&scardcllyiicuscan utilize phosphorus either as phosphate, pk~phite, or hypophosphibe. When cultures are supplied with PO, as the sole source of phosphorus, the hypophospnite is oxidized to phosphate, which accwtes in the medi d is theta metaboduring growth. g cell suspensions also have the ability to oxidize
The reaction is PC), is not ox whether the cells are grow medium. The hyp optim~ly between
Microbialadhption to extreme environments
65
monium sulfate fractionation of the cell-free extract showed that the PO, oxidation!, which is accompanied by the formation of NADH, requires at least three components: An ammonium sulfate fraction of the cell-free extract,
the residue fraction containing the respiratory chain, and NAD as cofactor. Most probably a second cofactor, as yet not characterized. is required to accomplish full activity.
6.D. VOGELS
One way in which microorganisms can oppose extreme conditions consists of a positive or negative tactic respotlse to a changing environment. Such a respor.se can be triggered by changes in temperature (thermotaxis) or in the chemical composition of the medium (chemotaxis). Adler ( 1966) and Mesibov and dler (1972) made excellent studies on the positive chemotaxis of E. co2i towards various nutrients, e.g. amino acids and sugars. rTtappeared that a tactic response is also observed towards certain chemicals which are not metabolized or even are not transported inward at all. Therefore, chemoreceptors, which recognize the compcunds, must be located in the ccl or cell membrane. These recepre quite specific, transfer the obtors, w served signal in such a way to the flagella that movement alters. oshland (1972) pointed out
that bacteria are too small to detect concentration differences over one body length in concentration gradients normally applied in studies on chemotaxis. They suggested that bacteria must be fitted with some kind of rudimentary memory. Such a memory combined with a ~dime~tary nerve system that is involved in the translation of chemoreception into alteration of the position of flagella enables the bacteria to fly away from extreme conditions to favourable ones.
eferences Adler, J., 1966, Chemotaxis in bacteria, Science 153, 708-716. Macnab, R.M. and D.E. Koshland, Jr., 1972, The gadientsensing mechanism in bacterial chemozaxis. &or. Natl. Acad. Sci. US 69,2509--2512. Mesibov, R. and J. Adler, 1972, Chemotaxis toward amino acids in E. coli, J. Racteriol. 112,315-326.