Organic-matter degradative potential of Halomonas glaciei isolated from frazil ice in the Ross Sea (Antarctica).
Halomonas glaciei isolated from frazil ice in the Ross Sea (Antarctica) during austral summer 2003 was phenotypically characterized and its capability of degrading organic matter was tested. We evaluated specific bacterial growth rates (mu) to understand at which temperatures bacterial growth shows a linear and direct relationship with the available substrate (4-22 degrees C) and afterwards we tested H. glaciei growth curves and degradative potential at 0, 10 and 37 degrees C using two different media (one enriched and one depleted in PO(4)). The strain grew exponentially only at 10 degrees C. The fastest hydrolysis rates were expressed by enzymes aimed at polysaccharide degradation (alpha-D-glucosidase, beta-D-glucosidase and beta-D-galactosidase) while alkaline phosphatase and aminopeptidase activities were rather low. Our data suggest a preferential demand for carbon derived from carbohydrates rather than from proteins: ectoenzyme activities transformed into carbon mobilization from organic polymers, showed that the total carbon potentially released from polysaccharides can be almost one order of magnitude higher than the protein carbon mobilization. Principal component analysis of the enzyme affinity separated the six experimental conditions, highlighting how different physical (temperature) and chemical (PO(4) enrichment or depletion) features actively lead to a differentiation in the efficiency of the ectoenzymes produced, resulting in preferential degradation of diverse kinds of organic substrates.
Celussi
Mauro
M
Dipartimento di Oceanografia Biologica, Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste, Italy. mcelussi@ogs.trieste.it
Balestra
Cecilia
C
Fabbro
Cinzia
C
Crevatin
Erica
E
Cataletto
Bruno
B
Umani
Serena Fonda
SF
Del Negro
Paola
P
D000864:Antarctic Regions; D001673:Biodegradation, Environmental; D050260:Carbohydrate Metabolism; D002244:Carbon / Q000378:metabolism; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D020459:Genes, rRNA; D006026:Glycoside Hydrolases / Q000378:metabolism; D020632:Halomonas / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*; D006868:Hydrolysis; D007053:Ice; D009930:Organic Chemicals / Q000378:metabolism*; D010641:Phenotype; D010710:Phosphates / Q000378:metabolism; D025341:Principal Component Analysis; D011506:Proteins / Q000378:metabolism; D012336:RNA, Ribosomal, 16S; D013379:Substrate Specificity; D013696:Temperature; D014871:Water Microbiology
D003470:Culture Media; D004269:DNA, Bacterial; D007053:Ice; D009930:Organic Chemicals; D010710:Phosphates; D011506:Proteins; D012336:RNA, Ribosomal, 16S; D002244:Carbon; D006026:Glycoside Hydrolases