Effects of methylated, organic, and inorganic substrates on microbial consumption of dimethyl sulfide in estuarine waters.

We examined the effects of a variety of amendments on the consumption of [U-C]dimethyl sulfide in a Georgia salt marsh. Methylated compounds, particularly those with dimethyl groups, significantly inhibited dimethyl sulfide consumption, while nonmethylated substrates had little effect. Dimethyl disulfide and dimethyl ether were the most effective inhibitors tested.

Effect of protistan grazing on the frequency of dividing cells in bacterioplankton assemblages.

Grazing by phagotrophic flagellates and ciliates is a major source of mortality for bacterioplankton in both marine and freshwater systems. Recent studies have demonstrated a positive relationship between clearance rate and prey size for bacterivorous protists. We tested the idea that, by selectively grazing the larger (more actively growing or dividing) cells in a bacterial assemblage, protists control bacterial standing stock abundances by directly cropping bacterial production.

Relative contributions of bacteria and fungi to rates of degradation of lignocellulosic detritus in salt-marsh sediments.

Specifically radiolabeled [C-lignin]lignocellulose and [C-polysaccharide]lignocellulose from the salt-marsh cordgrass Spartina alterniflora were incubated with an intact salt-marsh sediment microbial assemblage, with a mixed (size-fractionated) bacterial assemblage, and with each of three marine fungi, Buergenerula spartinae, Phaeosphaeria typharum, and Leptosphaeria obiones, isolated from decaying S. alterniflora. The bacterial assemblage alone mineralized the lignin and polysaccharide components of S.