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A bacterial strain able to degrade various sulfated galactans (carrageenans and agar) was isolated from the marine red alga Delesseria sanguinea. From the cell-free supernatant of cultures grown on crude i-carrageenan, a K-carrageenase was purified by ammonium sulfate fractionation, gel filtration on Sephacryl S 200 HR and ionexchange chromatography on DEAE -Sepharose-CL6B. The purified Ic-carrageenase was detected as a single protein upon SDS/PAGE. Its molecular mass was estimated at 40 kDa. Activity was observed against Kcarrageenan over the pH range 5.0-8.5 and was optimal at pH 7.2 in Tris buffer or 7.0 in Mops buffer. The enzyme activity remained stable at 30°C, but only for up to 1 h at 40°C. Analysis of the degradation products of the k--carrageenase by gel filtration and I3C-NMR spectroscopy indicated that the enzyme degrades K-carrageenan down to the level of the Ic-neocarratetraose sulfate. The properties of this new enzyme are compared with those of previously characterized carrageenases.Carrageenans are sulfated homopolymers of p-D galactopyranosyl-(I + 4) a-( +)-D-galactose, itself 1,3-linked. They occur in the cell wall and intercellular matrix of certain marine red algae [I]. Isolation and purification of various carrageenases from marine bacteria have been reported by several authors, especially the rc-carrageenase [2, 31 and I-carrageenase [4] from Pseudomonas carrageenovora, and the i-carrageenase from an unidentified Gram-negative, aerobic rod bacterium [5]. Degradation of carrageenan by marine bacteria which have yellow/orange pigments has also been reported [6 -81. The taxonomic position of this group has been recently clarified, but carrageenases from those bacteria have not yet been characterized [8].We have isolated from a red alga, such a carrageenandegrading bacterium, referred to as strain Dsij [8a]. Identification of the isolate according to the criteria described in [9] and determination of the phenotypic features indicate that it belongs in the genus Cytophaga. Incubation of the bacterium in Zobell medium, supplemented with various types of carrageenan or agar, resulted in the production of extracellular IC-and i-carrageenases or agarase activities. In the presence of crude 2-carrageenan, the strain simultaneously produces extracellular K -and I-carrageenases.The i-carrageenase from Dsij is unstable and its purification is in progress. This paper describes the purification and characterization of the K-carrageenase and compares its lytic properties with those of the rc-carrageenase of P. carrageenovora. The taxonomical investigation of the bacterial strain Dsij, the influence of the nature of the substrate on enzyme production and the purification of the i-carrageenase will be described in detail in a future report. MATERIALS AND METHODS OrganismThe strain Dsij was isolated from a live specimen of the red alga Delesseria sanguinea collected near Roscoff, Brittany, France, in November 1988. Isolation was performed on a plate in a basal salt medium [lo] containing 2% i-carrageenan. Th...

Protoplasts were isolated from female gametophytes of Chondrus crispus (Stackh.) using commercial cellulase and various carrageenases prepared from marine bacteria. Depending on the nature of the donor tissue (apices or whole thallus, wild or cultivated strains), yields ranged from 1.0-8.5×10(8) protoplasts per gram of fresh tissue. Preincubating the tissue with a potassium chelator, Kryptofix 222, enhanced protoplast yields by 30-50 %. Based on staining with fluorescein diacetate most protoplasts were viable. A few protoplasts regenerated a cell wall and divided.