N-140. Isolation and Characterization of Chitin-Utilizing Halophiles from the Great Salt Lake, UT

C. J. Oberg, K. M. Bowcutt, B. Burton, D. R. Cox, M. D. Zwolinski;
Weber State Univ., Ogden, UT.

The Great Salt Lake’s south arm contains a large biomass of brine flies and shrimp whose husks and exoskeletons are composed of chitin which accumulates and becomes an abundant carbon source in this unique hypersaline ecosystem. Isolation procedures were used to find halophilic microorganisms capable of degrading chitin. Samples obtained from Bridger Bay off Antelope Island were inoculated into enrichment media selective for chitinolytic halobacteria. Enrichment flasks containing a carbon-free halophile medium amended with 2.5 g l-1 chitin were incubated at 22oC in a shaker for three weeks. The biofilm that developed on the sides of the culture flask was used to inoculate a selective chitin agar. Agar plates were prepared to ensure that the chitin flakes would stay near the surface of the agar by allowing a layer of minimal halophilic agar to solidify and then pouring 10 ml of chitin agar as an overlay. Chitinolytic activity was identified as zones of clearing in the chitin layer. Fourteen isolates capable of growing on chitin were obtained from the enrichment cultures. Most isolates were obtained from exoskeleton debris collected near the shoreline with the majority being either Gram-negative rods or cocci. Nearly half of the isolates displayed pigmentation. Based on their 16S rRNA gene sequences, the isolates are related to common halophilic organisms including Gram-negative Halomonas sp. and Salinivibrio costicola, and Gram-positive Marinococcus sp., Bacillus baekryungensis, Salinicoccus roseus and Brachybacterium sp. This is the first survey of chitin-degrading organisms in a hypersaline environment. Chitin decomposition is vital to the cycling of C and N in this ecosystem so understanding how halophilic bacteria participate is important. Further, the chitinolytic enzymes of hypersaline organisms may be useful as novel insecticides or for bioremediation technology.