Abstract
BackgroundIn recent years there has been a global increase in reports of disease affecting marine sponges. While disease outbreaks have the potential to seriously impact on the survival of sponge populations, the ecology of the marine environment and the health of associated invertebrates, our understanding of sponge disease is extremely limited.Methodology/Principal FindingsA collagenolytic enzyme suspected to enhance pathogenicity of bacterial strain NW4327 against the sponge Rhopaloeides odorabile was purified using combinations of size exclusion and anion exchange chromatography. After achieving a 77-fold increase in specific activity, continued purification decreased the yield to 21-fold with 7.2% recovery (specific activity 2575 collagen degrading units mg−1protein) possibly due to removal of co-factors. SDS-PAGE of the partially pure enzyme showed two proteins weighing approximately 116 and 45 kDa with the heavier band being similar to reported molecular weights of collagenases from Clostridium and marine Vibrios. The enzyme degraded tissue fibres of several sponge genera suggesting that NW4327 could be deleterious to other sponge species. Activity towards casein and bird feather keratin indicates that the partially purified collagenase is either a non-selective protease able to digest collagen or is contaminated with non-specific proteases. Enzyme activity was highest at pH 5 (the internal pH of R. odorabile) and 30°C (the average ambient seawater temperature). Activity under partially anaerobic conditions also supports the role of this enzyme in the degradation of the spongin tissue. Cultivation of NW4327 in the presence of collagen increased production of collagenase by 30%. Enhanced enzyme activity when NW4327 was cultivated in media formulated in sterile natural seawater indicates the presence of other factors that influence enzyme synthesis.Conclusions/SignificanceSeveral aspects of the sponge disease etiology were revealed, particularly the strong correlation with the internal tissue chemistry and environmental temperature. This research provides a platform for further investigations into the virulence mechanisms of sponge pathogens.
Highlights
Reports of sponge disease are rapidly increasing with Mediterranean [1] and Caribbean [2] sponge populations most heavily affected
Disease outbreaks have the potential to seriously impact on the survival of sponge populations, the ecology of the marine environment and the health of associated invertebrates [6]
Sponges infected with strain NW4327 exhibited high levels of tissue necrosis and bacteria were observed burrowing through the collagenous spongin fibres
Summary
Reports of sponge disease are rapidly increasing with Mediterranean [1] and Caribbean [2] sponge populations most heavily affected. Reports suggest an increased prevalence of disease in sponges from Papua New Guinea [3], the Great Barrier Reef [4] and Mexico [5]. Disease outbreaks have the potential to seriously impact on the survival of sponge populations, the ecology of the marine environment and the health of associated invertebrates [6]. Only one study has confirmed Koch’s postulates by verifying that an a -proteobacterium (strain NW4327) was the primary pathogen of the Great Barrier Reef sponge Rhopaloeides odorabile [4]. While disease outbreaks have the potential to seriously impact on the survival of sponge populations, the ecology of the marine environment and the health of associated invertebrates, our understanding of sponge disease is extremely limited
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
