Cottrell, M. T. University of Delaware, cottrell@udel.edu
Kirchman, D. T. University of Delaware, kirchman@udel.edu

 
CHITINASE ACTIVITY AND CHITIN DEGRADATION DURING AN EXPERIMENTAL PHYTOPLANKTON BLOOM
 
Microbial degradation of particulate organic matter is an important aspect of carbon cycling and contributes to the production of dissolved organic matter, the largest pool of organic carbon in the ocean. We are studying chitin, a linear polysaccharide composed of beta 1-4 N-acetyl glucosamine produced by many marine organisms. We examined chitin degradation during phytoplankton blooms produced with and without copepods in incubations of coastal seawater enriched with N, P, Si and inoculated with Thalassiosira weissflogii. Three chitinolytic activities (MUF-diNAG hydrolysis, 14C-chitin respiration, and 14C-chitin solubilization) were higher in the bloom treatments than in the control. Furthermore, the ratio of production of 14C-DOM from 14C-chitin to respiration of 14C-chitin was lowest in the control and highest in the bloom treatments. Degradation of 14-C chitin and MUF-diNAG hydrolysis did not co-vary. Bacterial production increased 6-fold during the bloom, while the percent of bacterial production supported by degradation of particulate chitin decreased (2.7% to 0.8%) and the percent supported by chitin hydrolysis increased about 10-fold (4.7% to 42%). During blooms, polymer hydrolysis and particle degradation became uncoupled and polymer hydrolysis appeared to support a larger portion of bacterial production than particle degradation.
 
Day: Thursday, Feb. 4
Time: 02:00 - 02:15pm
Location: Sweeney Center
 
Code: SS33TH0200S