cryptoendolithic microbial community in the antarctic cold desert
Terrestrial biology carbon metabolism by the cryptoendolithic microbial community in the antarctic cold desert In situ
J. R0BIE VESTAL Department of Biological Sciences University of Cincinnati Cincinnati, Ohio 45221
E. IMRE FRIEDMANN Department of Biological Science Florida State University Tallahassee, Florida 32306
The ability of the cryptoendolithic microbial community to actively metabolize organic and inorganic carbon sources was studied in situ at Linnaeus Terrace (77°36'S 161°05'E; 1,650 meters in altitude) in the Asgard Range, southern Victoria Land. Previous studies (recently reviewed by Friedmann 1982) have shown that this community includes algae and fungi (which form a lichen association), as well as bacteria. The lichen algae (phycobionts) are the primary providers of organic nutrients for the fungi and bacteria in this simple ecosystem. Our purpose is to investigate carbon metabolism of this cryptoendolithic community under the environmental extremes of the antarctic cold desert. Portions of large, flat rocks colonized by cryptoendolithic lichens were soaked with various carbon-14 (14C)-labeled organic (acetate, glucose, and glutamate) and inorganic (bicarbonate) carbon sources at micromole concentrations. After incubation under ambient conditions, the rocks were transported to the Eklund Biological Laboratory at McMurdo Station, where the soaked portions were removed and crushed to sand. The 14 C-labeled lipids were extracted with chloroform and methanol according to the procedures of Bligh and Dyer (1959) as modified by White and others (1977). The lipid extract also was used to determine the active biomass expressed in lipid phosphate (White et al. 1979). As shown in table 1, incorporation of organic compounds increased with time and was not affected by darkness. This represents the active metabolism of heterotrophs (fungi and nonphotosynthetic bacteria) in the community. When 4 C-bicarbonate was added to the rock surface and allowed to soak into the lichen zone, incorporation increased with time and was light dependent. There was some bicarbonate incorporation in the aluminum foil-covered "dark" control rock, 190
suggesting incorporation by a heterotrophic microbial population. Similar results were obtained in other experiments (not reported here) with crushed rock samples under controlled light and temperature conditions. Our experiments suggest that the cryptoendolithic microbial community actively metabolizes dissolved carbon compounds. Friedmann (1978) had previously shown that melting snow is the source of water for cryptoendolithic lichens, and it seems reasonable to postulate that bicarbonates dissolved in snowmelt are used by the organisms. To study the uptake of gaseous carbon dioxide (CO2), inverted glass jars were attached to lichen-colonized rocks and 14CO2 was produced by acidifying 14 C-bicarbonate in the closed jars. The rocks were incubated in situ and then transported to the Eklund Biological Laboratory for analysis of 14C-incorporation and for biomass determination. Results are shown in table 2. No measurable incorporation was found after 7 days under ambient conditions. After 2 weeks, CO2 incorporation into cellular lipids could be demonstrated, both in dry rocks and in rocks soaked with CO2-free water prior to incubation. The fact that there was appreciably more incorporation into the "dark" control further suggests nonphotosynthetic CO 2 fixation. The amounts of biomass in the samples were in the same order of magnitude, and the variation probably reflects the difference in thickness of the lichen zone in rocks (Friedmann 1982). Field personnel during the 1981-82 season included E. Imre Friedmann, Mason E. Hale, Jr., Christopher P. McKay, Stephen A. Norton, and J. Robie Vestal. This research was supported by National Science Foundation grant DPP 80-17581 to E. I. Friedmann.
Table 1. Incorporation of 14C-Iabeled carbon sources Into lipids of the cryptoendolithlc microbial community in situ at Linnaeus Terrace, Asgard Range (Incubation period 5 or 14 days, from 25 November 1981) Carbon source 5 days 14 days 14 days (darka) 14C-acetate 943b 1,504 1,546 14C-glutamate 562 1,527 N.D.0 14C-glucose 948 945 1,096 462 14C-bicarbonate 437 1,085 "Dark = rock covered with aluminum foil. b Figures indicate disintegrations per minute per micromole of lipid phosphate. C ND = not determined. ANTARCTIC JOURNAL
Table 2. incorporation of 14CO2 into lipids incubated in situ at Linnaeus Terrace, Asgard Range, and biomass in respective rock samples expressed in lipid phosphate (Incubation period 7, 14, or 16 days, from 25 November 1981)
Incorporation (disintegration per minute per micromole lipid phosphate) Biomass (micromole lipid phosphate per square centimeter)
7 days (dry rock)
14 days (wet" rock)
16 days (dry rock)
N.D.0
647 ± 117d
395 ± 126
0.110 ± 001d 0.060 ± 0.004
0.068 ± 0.02
16 days (dark , b dry rock)
653 ± 163
0.050 ± 0.006
awet = soaked with CO 2 4ree water prior to incubation. b Oark = glass jars were covered with aluminum toil. C N . D . = none detected (i.e., counts were not above 2 times background). dMean ± SD (n = 3).
References Bligh, E. G., and Dyer, W. J . 1959. A rapid method of total lipid extraction
and purification. Canadian Journal of Biochemistry and Physiology, 37, 911-917. Friedmann, E. I. 1978. Melting snow in the dry valleys is a source of water for endolithic microorganisms. Antarctic Journal of the U.S., 13(4), 162-163.
Physiological adaptations of biota in antarctic oasis lakes B. C. PARKER, G. M. SIMMONS, JR., M. KASPAR, and A. MIKELL Biology Department and
F. C. LOVE Geology Department Virginia Polytechnic Institute and State University Blacksburg, Virginia 2406
K. C. SEABURG Department of Biology Xavier College New Orleans, Louisiana 70035
R. A. WHARTON, JR. Ames Research Center Moffett Field, California 04035
1982 REVIEW
Friedmann, E. I. 1982. Endolithic microorganisms in the antarctic cold desert. Science, 215, 1045-1053. White, D. C., Bobbie, R. J . , Morrison, S. J . , Oosterhof, D. K., Taylor, C. W., and Meeter, D. A. 1977. Determination of microbial activity of estuarine detritus by relative rates of lipid biosynthesis. Limnology and Oceanography, 22, 1089-1099.
White, D. C., Davis, W. M., Nickels, J . S., King, J . D., and Bobbie, R. J. 1979. Determination of the sedimentary microbial biomass by extractable lipid phosphate. Oceologia (Berlin), 40, 51-62.
Our research seeks to identify and characterize the extent to which southern Victoria Land lake communities, species, or strains are physiologically adapted for survival and growth under certain environmental extremes. Field studies during the 1980-81 and 1981-82 austral summers at Lakes Bonney, Fryxell, Hoare (Taylor Valley), and Vanda (Wright Valley) have addressed adaptions to (1) low light, (2) low temperature, (3) hypersalinity, (4) supersaturated oxygen, (5) nutrient limitations (e.g., nitrogen, phosphorus), (6) lack of turbulence, and (7) desiccation or freeze-thaw cycles. We list here only new information on adaptations to variables 1-4 above and discuss briefly the unique stromatolites and endemic algal species. For additional information, see Allnutt and others (1981), Cathey and others (1981, in press), Kaspar and others (in press), Love, Simmons, Wharton, and Parker (in press), Love, Simmons, Wharton, and Parker (in press), Parker and others (1980, 1982, in press, Parker and Simmons (1981), Seaburg, Parker, and Simmons (1981), Simmons and others (1981), Wharton (1982), and Wharton and others (1982). Adaptations to low light. The perennial 3-6-meter-thick, rockand soil-strewn ice covers of the four lakes vary in their average surface light transmittance (as percent) and average extinction coefficients (E PAR) for photosynthetically available radiation (PAR) of 400-700-nanometer wavelength range for their underlying waters: Bonney, percent, 0.157 EPA R; Hoare, 1.7 percent,
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J. R0BIE VESTAL Department of Biological Sciences University of Cincinnati Cincinnati, Ohio 45221
E. IMRE FRIEDMANN Department of Biological Science Florida State University Tallahassee, Florida 32306
The ability of the cryptoendolithic microbial community to actively metabolize organic and inorganic carbon sources was studied in situ at Linnaeus Terrace (77°36'S 161°05'E; 1,650 meters in altitude) in the Asgard Range, southern Victoria Land. Previous studies (recently reviewed by Friedmann 1982) have shown that this community includes algae and fungi (which form a lichen association), as well as bacteria. The lichen algae (phycobionts) are the primary providers of organic nutrients for the fungi and bacteria in this simple ecosystem. Our purpose is to investigate carbon metabolism of this cryptoendolithic community under the environmental extremes of the antarctic cold desert. Portions of large, flat rocks colonized by cryptoendolithic lichens were soaked with various carbon-14 (14C)-labeled organic (acetate, glucose, and glutamate) and inorganic (bicarbonate) carbon sources at micromole concentrations. After incubation under ambient conditions, the rocks were transported to the Eklund Biological Laboratory at McMurdo Station, where the soaked portions were removed and crushed to sand. The 14 C-labeled lipids were extracted with chloroform and methanol according to the procedures of Bligh and Dyer (1959) as modified by White and others (1977). The lipid extract also was used to determine the active biomass expressed in lipid phosphate (White et al. 1979). As shown in table 1, incorporation of organic compounds increased with time and was not affected by darkness. This represents the active metabolism of heterotrophs (fungi and nonphotosynthetic bacteria) in the community. When 4 C-bicarbonate was added to the rock surface and allowed to soak into the lichen zone, incorporation increased with time and was light dependent. There was some bicarbonate incorporation in the aluminum foil-covered "dark" control rock, 190
suggesting incorporation by a heterotrophic microbial population. Similar results were obtained in other experiments (not reported here) with crushed rock samples under controlled light and temperature conditions. Our experiments suggest that the cryptoendolithic microbial community actively metabolizes dissolved carbon compounds. Friedmann (1978) had previously shown that melting snow is the source of water for cryptoendolithic lichens, and it seems reasonable to postulate that bicarbonates dissolved in snowmelt are used by the organisms. To study the uptake of gaseous carbon dioxide (CO2), inverted glass jars were attached to lichen-colonized rocks and 14CO2 was produced by acidifying 14 C-bicarbonate in the closed jars. The rocks were incubated in situ and then transported to the Eklund Biological Laboratory for analysis of 14C-incorporation and for biomass determination. Results are shown in table 2. No measurable incorporation was found after 7 days under ambient conditions. After 2 weeks, CO2 incorporation into cellular lipids could be demonstrated, both in dry rocks and in rocks soaked with CO2-free water prior to incubation. The fact that there was appreciably more incorporation into the "dark" control further suggests nonphotosynthetic CO 2 fixation. The amounts of biomass in the samples were in the same order of magnitude, and the variation probably reflects the difference in thickness of the lichen zone in rocks (Friedmann 1982). Field personnel during the 1981-82 season included E. Imre Friedmann, Mason E. Hale, Jr., Christopher P. McKay, Stephen A. Norton, and J. Robie Vestal. This research was supported by National Science Foundation grant DPP 80-17581 to E. I. Friedmann.
Table 1. Incorporation of 14C-Iabeled carbon sources Into lipids of the cryptoendolithlc microbial community in situ at Linnaeus Terrace, Asgard Range (Incubation period 5 or 14 days, from 25 November 1981) Carbon source 5 days 14 days 14 days (darka) 14C-acetate 943b 1,504 1,546 14C-glutamate 562 1,527 N.D.0 14C-glucose 948 945 1,096 462 14C-bicarbonate 437 1,085 "Dark = rock covered with aluminum foil. b Figures indicate disintegrations per minute per micromole of lipid phosphate. C ND = not determined. ANTARCTIC JOURNAL
Table 2. incorporation of 14CO2 into lipids incubated in situ at Linnaeus Terrace, Asgard Range, and biomass in respective rock samples expressed in lipid phosphate (Incubation period 7, 14, or 16 days, from 25 November 1981)
Incorporation (disintegration per minute per micromole lipid phosphate) Biomass (micromole lipid phosphate per square centimeter)
7 days (dry rock)
14 days (wet" rock)
16 days (dry rock)
N.D.0
647 ± 117d
395 ± 126
0.110 ± 001d 0.060 ± 0.004
0.068 ± 0.02
16 days (dark , b dry rock)
653 ± 163
0.050 ± 0.006
awet = soaked with CO 2 4ree water prior to incubation. b Oark = glass jars were covered with aluminum toil. C N . D . = none detected (i.e., counts were not above 2 times background). dMean ± SD (n = 3).
References Bligh, E. G., and Dyer, W. J . 1959. A rapid method of total lipid extraction
and purification. Canadian Journal of Biochemistry and Physiology, 37, 911-917. Friedmann, E. I. 1978. Melting snow in the dry valleys is a source of water for endolithic microorganisms. Antarctic Journal of the U.S., 13(4), 162-163.
Physiological adaptations of biota in antarctic oasis lakes B. C. PARKER, G. M. SIMMONS, JR., M. KASPAR, and A. MIKELL Biology Department and
F. C. LOVE Geology Department Virginia Polytechnic Institute and State University Blacksburg, Virginia 2406
K. C. SEABURG Department of Biology Xavier College New Orleans, Louisiana 70035
R. A. WHARTON, JR. Ames Research Center Moffett Field, California 04035
1982 REVIEW
Friedmann, E. I. 1982. Endolithic microorganisms in the antarctic cold desert. Science, 215, 1045-1053. White, D. C., Bobbie, R. J . , Morrison, S. J . , Oosterhof, D. K., Taylor, C. W., and Meeter, D. A. 1977. Determination of microbial activity of estuarine detritus by relative rates of lipid biosynthesis. Limnology and Oceanography, 22, 1089-1099.
White, D. C., Davis, W. M., Nickels, J . S., King, J . D., and Bobbie, R. J. 1979. Determination of the sedimentary microbial biomass by extractable lipid phosphate. Oceologia (Berlin), 40, 51-62.
Our research seeks to identify and characterize the extent to which southern Victoria Land lake communities, species, or strains are physiologically adapted for survival and growth under certain environmental extremes. Field studies during the 1980-81 and 1981-82 austral summers at Lakes Bonney, Fryxell, Hoare (Taylor Valley), and Vanda (Wright Valley) have addressed adaptions to (1) low light, (2) low temperature, (3) hypersalinity, (4) supersaturated oxygen, (5) nutrient limitations (e.g., nitrogen, phosphorus), (6) lack of turbulence, and (7) desiccation or freeze-thaw cycles. We list here only new information on adaptations to variables 1-4 above and discuss briefly the unique stromatolites and endemic algal species. For additional information, see Allnutt and others (1981), Cathey and others (1981, in press), Kaspar and others (in press), Love, Simmons, Wharton, and Parker (in press), Love, Simmons, Wharton, and Parker (in press), Parker and others (1980, 1982, in press, Parker and Simmons (1981), Seaburg, Parker, and Simmons (1981), Simmons and others (1981), Wharton (1982), and Wharton and others (1982). Adaptations to low light. The perennial 3-6-meter-thick, rockand soil-strewn ice covers of the four lakes vary in their average surface light transmittance (as percent) and average extinction coefficients (E PAR) for photosynthetically available radiation (PAR) of 400-700-nanometer wavelength range for their underlying waters: Bonney, percent, 0.157 EPA R; Hoare, 1.7 percent,
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