AME 16:45-52 (1998)  -  doi:10.3354/ame016045

ABSTRACT: Acrylate produced from dimethylsulphoniopropionate (DMSP) by Phaeocystis has been claimed to inhibit bacterial growth. However, the concentrations of acrylate measured in seawater during Phaeocystis blooms are not high enough to expect inhibition of bacterial growth. In this study, the total acrylate in Phaeocystis cultures free from bacteria was measured. The concentration found in the exponential phase of growth was similar (0.1 to 1.0 μM) to earlier field reports, but the amount found in the stationary phase of growth was much higher (1 to 4 μM). Acrylate in cultures, as well as in field samples, was found to be located in the mucous layer of the colony. 'Microscale' concentrations in that layer were more than 1000-fold higher (1.3 to 6.5 mM) than the total concentration found in the unfractionated culture. Such high concentrations could have an antimicrobial effect. However, acrylate appears to be adsorbed to the mucus and may be inaccessible to bacteria, including those that consume acrylate. As soon as the colonies started to decay, acrylate was released into the surrounding environment, and since it is not detected in bloom samples, it is apparently consumed by bacteria.

KEY WORDS: Phaeocystis · Bacteria · Acrylate · Colonies · Mucus · DMSP · Inhibition