Extracellular enzymes are a first step in microbial degradation of organic compounds exceeding 600 Dalton in molecular weight. Sachia J Traving, Uffe H Thygesen, Lasse Riemann and Colin A Stedmon investigated the apparent refractory nature of dissolved organic matter in the oceans in terms of bacterial enzyme strategies (free versus cell bound). The authors’ model reveals that surface-attached and free enzymes generate unique enzyme and substrate fields and each strategy has distinctive advantages. For solitary cells the surface-attached enzymes are the most beneficial strategy. They also show that in the deep ocean, specific dissolved organic compounds likely persist below a threshold concentration and, therefore, can be perceived as resistant to degradation and utilization by free-living bacteria.
The accepted manuscript can be found here