Regulation of microbial enzymatic degradation of organic matter in deep-sea sediments

Abstract

The enzymatic response of a natural deep-sea microbial community to input of organic matter was investigated by substrate enrichment experiments. Sediments from the BIOTRANS area at 47"N 20°W in the NE Atlantic (4500 m depth) were supplied with particulate and dissolved organic matter from stenhzed net plankton and incubated under in situ pressure and temperature. Changes in the potential hydrolytic activities of the extracellular enzymes a-and P-glucosidase, chitobiase, lipase and aminopeptidase were observed over a 15 d incubation period. Direct microscopic counts and phospholipid concentrations were used as measures of microbial biomass. Induction of enzyme production proportional to the supply of organic matter was found for enzymes degrading structural polysaccharides (P-glucosidase, chitobiase), while aminopeptidase activity was Inhibited and no clear effect was found for enzymes degrading storage compounds (a-glucosidase and lipase). Particulate organic matter induced higher enzyme production than equivalent amounts of dissolved organic matter. Only a slight increase in microbial biomass was observed until the end of the experiment after 15 d indicating that changes in enzyme activity were not due to bacterial growth. The observations give evidence that the production of enzymes in natural mixed microbial communities is directly regulated by the supply of appropriate food.

Enrichment and Cultivation of Microorganisms from Sediment from the Slope of the Peru Trench (ODP Site 1230)

“…These genera are also commonly found in deep sediment studies, especially those in the Pacific (Wang et al, 2004). The trend in extracellular degradative enzyme production agrees with previously published results of deep-sea sediment isolates and corresponds to available nutrient sources, suggesting a possible adaptation to this environment or competitive advantage within this ecosystem (Boetius and Lochte, 1994;Luna et al, 2004;Wang et al, 2004). The one Vibrio sp.…”

“…Chitinase activity was not seen for any of the isolates tested. The frequency of protease and esterase production may reflect the substrate availability of deep seafloor areas where proteins and lipids are present as substrates and possible nutrients (Boetius and Lochte, 1994;Luna et al, 2004).…”

Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

“…The latter approach usually involves estimating the hydrolytic potential of microbial communities by amending sediments with ffuorescently labeled precursors that serve as proxy organic macromolecules. A particularly common Huorophore is methylumbelliferyl (MUF) attached to a monomer such as a monosaccharide or an amino acid (Boetius and Lochte, 1994;Boschker and Cappenberg, 1994;Hoppe, 1983;King, 1986;Meyer-Reil, 1986). When these labels are attached to a monomer, they may fail to discern the activities of true extracellular enzymes because they are small enough to enter the bacterial periplasmic space.…”

The phosphorus release pathways and their mechanisms driven by organic carbon and nitrogen in sediments of eutrophic shallow lakes

“…The extracellular enzymes, including leucine aminopeptidase (LAP), β-D-glucoside (GLU) and lipase, were measured fluorometrically according to Boetius and Lochte (1994), using the methylumbelliferone (MUF) labelled substrates MCA-leu (L-leucine-4-methylcoumarinyl-7-amid HCl), MUF-glu (MUG-Beta-D-glucopyranoside) and MUF-stearate. Alkaline phosphatase activity (APA) was analyzed spectrophotometrically as p-nitrophenol (p-NP) resulting from the cleavage of phosphate from p-nitrophenylphosphate (p-NPP) (Sayler et al, 1979).…”