Isolation and characterization of a sea cucumber fucoidan-utilizing marine bacterium. AIMS:  To isolate a fucoidan-utilizing strain from seawater for sea cucumber fucoidan degradation. METHODS AND RESULTS:  The utilization of sea cucumber fucoidan was monitored by H(2)SO(4)-phenol assay for neutral sugar. The bacterium CZ1127 was isolated from seawater and shown to have a relatively large maximum fucoidan-utilizing rate of 81.5%. CZ1127 was confirmed to belong to the family Flavobacteriaceae by 16S rDNA and physiological analyses. This strain has an ability to utilize fucoidans extracted from various sea cucumbers to different degrees. Both extracellular and intracellular enzymes of CZ1127 could degrade sea cucumber fucoidan, as confirmed by high-performance size exclusion chromatography. The M(r) of sea cucumber fucoidan could be reduced from 792.6 kDa to at least 3.7 kDa by the crude intracellular enzyme of this strain. CONCLUSIONS:  The marine bacterial strain CZ1127, which belongs to the family Flavobacteriaceae, was found to utilize various sea cucumber fucoidans and furthermore showed promise in sea cucumber fucoidan enzymatic degradation and oligosaccharide preparation. SIGNIFICANCE AND IMPACT OF THE STUDY:  The finding of a novel source can be applied in sea cucumber fucoidan enzymatic degradation. Furthermore, it is the first definite report of a bacterial strain that can utilize the fucoidans from various sea cucumbers.