Enumeration of Hydrocarbon Degrading Bacteria and Degrading Kinetics as an Indicator of Water Quality
Sea Grant
Project Completion Report R-96-1-00
Baqar R. Zaidi
May 16, 2002
Water quality, biodegradation of polyaromatic hydrocarbons (PAHs) by BIOLOG MT plates and enumeration of hydrocarbon degrading bacteria by over-layer technique were studied in Guayanilla Bay water. A Pseudomonas spp. and one Aeromonas spp. capable of degrading naphthalene and phenanthrene respectively were isolated, purified and identified by standard microbial techniques. One strain of bacterium was also identified by molecular techniques. Results showed that rain is the single most important factor affecting water quality, turbidity, biodegradation potential and presence of number of hydrocarbon-degrading bacteria in the Bay. Samples from an offshore site were used as control.
Following are specific conclusions of this study:
1. Turbidity increases microbial activity, thus enhanced biodegradation was observed in sampling stations closer to the shore where mixing of sediments take place.
2. More biodegradation in areas closer to source of pollution. Thus, more biodegradation was observed in Punta Guayanilla, El Faro and Guayanilla beach that closer to port and power plants.
3. Within reef samples highest microbial activity was found in Cayo Rio and lowest in Arrecife Unitas. Cayo Rio is closer to the shore than Arrecife Unitas, thus further confirming the above observation.
4. Punta Guayanilla showed the highest biodegradation of PAHs. More naphthalene and phenanthrene degrading bacteria were also found here. Mangrove provide rich source of organic material in Punta Guayanilla. Thus higher biodegradation results at this site were not unexpected, as it is known that more biodegradation of toxic chemicals occurs in the presence of other organic substrates (Schmidt et. al., 1987, Zaidi, et. al., 1995, 96).
5. Low values of dissolved oxygen (DO) at Punta Guayanilla also support the above conclusion.
6. Confirming the identity of Alteromonas spp tested the reliability of DNA sequencing method. This bacterial identification method is less tedious and more reliable than the conventional phenotypic identification method.
Peer Review Publications
1. Lynne M. Hinkey, Baqar R. Zaidi and Barry Volson. Impacts to marine water and sediment quality due to marinas and recreation boating in the northeast Caribbean – submitted to Water Research.
2. Baqar R. Zaidi, Lynne M. Hinkey, Nydia Rodriguez, Govind Nadathur and Syed H. Imam. Biodegradation of toxic chemicals in Guayanilla Bay: Confirmation of identity of phenanthrene-degrading bacterium by molecular techniques – To be submitted soon to Marine Pollution Bulletin.
Symposia and Workshops Attended:
a. International: Baqar R. Zaidi, Lynne M. Hinkey, Nydia Rodríguez and Syed H. Imam. Biodegradation of PAHs in the Caribbean Coastal Water. Poster presented in the First International Congress on Petroleum Contaminated Soils, Sediments and Water. August 14-17, 01 in Imperial College London, UK.
b. National: Enumeration of PAHs as an indicator of water quality in the Caribbean Coastal Water. Nydia R. Rodríguez and Baqar R. Zaidi. Poster presented in Annual Meeting of American Society for Microbiology, May 01.
Student Thesis: Nydia R. Rodríguez, supported by this grant will be defending her thesis during June 2002.