Open AccessOrganic‐matter degradative potential of Halomonas glaciei isolated from frazil ice in the Ross Sea (Antarctica)
Author(s) -
Celussi Mauro,
Balestra Cecilia,
Fabbro Cinzia,
Crevatin Erica,
Cataletto Bruno,
Fonda Umani Serena,
Del Negro Paola
Publication year - 2008
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2008.00551.x
Subject(s) - halomonas , biology , organic matter , polysaccharide , substrate (aquarium) , starch , carbon fibers , food science , environmental chemistry , bacteria , biochemistry , ecology , halophile , chemistry , materials science , composite number , composite material , genetics
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 (μ) to understand at which temperatures bacterial growth shows a linear and direct relationship with the available substrate (4–22 °C) and afterwards we tested H. glaciei growth curves and degradative potential at 0, 10 and 37 °C using two different media (one enriched and one depleted in PO 4 ). The strain grew exponentially only at 10 °C. The fastest hydrolysis rates were expressed by enzymes aimed at polysaccharide degradation (α‐ d ‐glucosidase, β‐ d ‐glucosidase and β‐ 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.