Bacterial profiles in healthy and Montipora white syndrome affected Montipora capitata mucus and the identification of potential etiologic agents

Thesis (M.S.)--University of Hawaii at Manoa, 2008.Includes bibliographical references (leaves 59-69).ix, 87 leaves, bound ill. 29 cmMontipora white syndrome (MWS) is a progressive tissue loss disease that affects Montipora capitata, a major reef building coral in Kaneohe Bay, Oahu. Chronic MWS manifests as focal to multifocal variably-sized areas of tissue loss, revealing an intact white skeleton bordered by normal appearing tissue. Acute MWS progresses faster than chronic and manifests as a large solitary area of tissue loss revealing intact white skeleton bordered by pale tissue that transitions into normally colored tissue. Culture-dependant methods were used to determine the bacterial community structure associated with healthy and MWS affected M capitata mucus. Healthy mucus contained 5.59 x 102 CFU/ml of culturable bacteria that was predominantly Alteromonas and Streptomyces. MWS affected mucus samples had an average of 25.6 times higher bacterial load at 1.42 x 104 CFU/ml of mucus. The culturable bacterial community structure of mucus from diseased coral was primarily composed of Vibrio spp., in particular, V. harveyi. The second most abundant bacteria isolated from mucus was Pseudoalteromonas and Ruegeria in acute and chronic MWS, respectively. Based on these bacterial profiles, Alteromonas, V. harveyi, Pseudoalteromonas and Ruegeria isolates were selected for in vitro challenge experiments. Alteromonas was used as a negative bacterial control because it is commonly found in abundance in healthy M capitata mucus. Preliminary challenge experiments eliminated V. harveyi and Ruegeria as etiologic agents. Though no tissue loss was observed, mucus after inoculation with Ruegeria had a slightly elevated CFU/ml. Fragments exposed to Pseudoalteromonas had varying responses to the challenge. Tissue loss, thinning and, alternatively, no apparent signs of deteriorating health were all observed after the challenge with Pseudoalteromonas. Overall. CFU/ml of mucus was increased post challenge with Pseudoalteromonas for all three observations. In future studies, additional challenge replicates should be conducted to further investigate the role of Pseudoalteromonas in coral pathogenesis