Vibrio sp. causing Porites ulcerative white spot disease

Abstract

The causative agent of the Indo-Pacific coral disease, Porites ulcerative white spot syndrome (PUWS), that affects Porites spp. and a few other coral genera has so far remained unidentified. Inoculation of thiosulphate citrate bile sucrose (TCBS) agar with tissue material from Porites cylindrica infected with white spot produced colonies of approximately 3 mm diameter consisting of Gram-negative, motile, non-sucrose-fermenting, slightly curved rods with a minimum NaCl requirement of 0.3%. Three of these putative Vibrio sp. isolates were used for infection trials that included different stages of cell growth. Four modes of inoculation and 3 stages of bacterial cell growth were considered for testing Koch's postulates. Stationary phase cells proved more consistently infectious than did exponentially growing or starved cells using a 1-step immersion technique at cell concentrations of 10 4 cells ml -1. A 1-step immersion technique proved more reliable in producing signs of white spot than did other techniques, such as injection, smearing and 2-step immersion of the inoculum. At inoculum densities >10 4 cells ml -1 further signs of disease, such as tissue degradation and bleaching, also became evident. At elevated temperatures (> 29°C) bleaching remained absent for at least 2 mo from non-inoculated corals serving as controls, but was observed in artificially infected coral fragments. Of the 9 seawater aquaria containing healthy specimens of P. cylindrica, 6 showed signs of white spot 15 d after infection with an isolate tentatively identified as Vibrio sp. Based on 99% similarity of its 16S rRNA gene sequence and selected phenotypical features, this isolate revealed a close relationship to V. natriegens and V. parahaemolyticus. KEY WORDS: Indopacific coral disease · Porites · Causative agent · Vibrio Resale or republication not permitted without written consent of the publisherDis Aquat Org 90: [93][94][95][96][97][98][99][100][101][102][103][104] 2010 ora spp., Montastrea spp. and Pocillopora damicornis (Rosenberg et al. 2007). Vibrio species are widespread copiotropic constituents of mesophilic microbial communities that favor organic pollution from shellfish and fish cultivation in coastal marine environments (Colwell et al. 1977, Colwell 1996, Reichardt et al. 2007). This group also harbors the causative agents of an extremely wide range of diseases of commercial marine fishes and shellfish (Bruno et al. 1998, Robertson et al. 1998, Lacoste et al. 2001). At year-round surface water temperatures between 27 and 33°C coral reefs in the vicinity of intensive milkfish Chanos chanos mariculture at Cape Bolinao (Lingayen Gulf, Philippines) are particularly exposed to high densities of different populations of Vibrio spp. (W. T. Reichardt et al. unpubl. data). Thus, a highly selective enrichment medium for marine vibrios, such as thiosulphate citrate bile sucrose (TCBS) agar (Bolinches et al.1988), was considered as first choice for isolating test strains from white spots of diseased Porites cylindrica to ...

White Syndrome-Affected Corals Have a Distinct Microbiome at Disease Lesion Fronts

“…Tissue loss associated with Indo-Pacific WSs has been attributed to a number of etiological agents, including Vibrio bacteria (20)(21)(22)(23)(24), apoptosis (25), ciliates (11,26), helminths (11), viruses (27), and intraspecific chimeric parasites (11,28), suggesting that distinct and potentially distinguishable forms of WSs exist. Based on logical deduction, we contend that the WS lesions observed in this study are not the result of apoptosis or infection by Vibrio bacteria, ciliates, fungi, cyanobacteria, or helminths, because of the low levels and inconsistent presence of these organisms at WS lesion fronts.…”

Community Shifts in the Surface Microbiomes of the Coral Porites astreoides with Unusual Lesions

“…In diseased Porites spp., symptoms can be fairly general, making assignment of gross lesion morphology difficult between diseases. The fulfillment of Koch's postulates linked three closely related strains of Vibrio to the ulcerative white spot disease of P. cylindrica [13], but causes of other observed abnormalities remain elusive. While agents responsible for some of the observed etiologies have been identified and Koch's postulates fulfilled either directly (reviewed by [12], [15]) or through the use of host-specific phages [18]–[21], it is likely that some coral diseases are not caused by specific pathogens.…”

Impact of milk fish farming in the tropics on potentially pathogenic vibrios

“…Certain as yet unclassified sucrose-negative vibrios that cause ulcerative white spot disease in Porites spp. corals at Bolinao may exemplify a latent pathogenic potential of sucrose negative vibrios of the study area toward marine animals (Arboleda and Reichardt, 2010), that deserves further taxonomic examination.…”