1. © Bacterial Diversity Of A Cyanobacterial Mat Degrading Petroleum Compounds At Elevated Salinities And Temperatures Abed, RMM; Al-Thukair, A; de Beer, D BLACKWELL PUBLISHING, FEMS MICROBIOLOGY ECOLOGY; pp: 290-301; Vol: 57 King Fahd University of Petroleum & Minerals http://www.kfupm.edu.sa Summary Cyanobacterial mats of the Arabian Gulf coast of Saudi Arabia experience extreme conditions of temperature and salinity. Because they are exposed to continuous oil pollution, they form ideal models for biodegradation under extreme conditions. We investigated the bacterial diversity of these mats using denaturing gradient gel electrophoresis and 16S rRNA cloning, and tested their potential to degrade petroleum compounds at various salinities (fresh water to 16%) and temperatures (5 to 50 degrees C). Cloning revealed that c. 15% of the obtained sequences were related to unknown, possibly novel bacteria. Bacteria belonging to Beta-, Gamma- and Deltaproteobacteria, Cytophaga-Flavobacterium-Bacteroides group and Spirochetes, were detected. The biodegradation of petroleum compounds at different salinities by mat microorganisms showed that pristine and n-octadecane were optimally degraded at salinities between 5 and 12% (weight per volume NaCl) whereas the optimum degradation of phenanthrene and dibenzothiophene was at 3.5% salinity. The latter compounds were also degradable at 8% salinity. The same compounds were degraded at temperatures between 15 and 40 degrees C but not at 5 and 50 degrees C. The optimum temperature of degradation was 28-40 degrees C for both aliphatics and aromatics. We conclude that the studied microbial mats from Saudi Arabia are rich in novel halotolerant and thermotolerant microorganisms with the potential to degrade petroleum compounds at elevated salinities and temperatures. References: Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

2. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. © ABED RMM, 2002, APPL ENVIRON MICROB, V68, P1674 ABED RMM, 2002, ARCH MICROBIOL, V177, P361 ALDAHER R, 1998, ENVIRON INT, V24, P175 ALHADHRAMI MN, 1996, MAR POLLUT BULL, V32, P351 ALMAGHRABI IMA, 1999, ENERG SOURCE, V21, P17 ALTHUKAIR AA, 1993, MAR POLLUT BULL, V27, P229 ANNWEILER E, 2000, APPL ENVIRON MICROB, V66, P518 BACKMAN A, 2005, MICROB ECOL, V48, P246 BALBA MT, 1998, ENVIRON INT, V24, P163 BENLLOCH S, 2002, ENVIRON MICROBIOL, V4, P349 COHEN Y, 1989, MICROBIAL MATS PHYSL, P22 COULON F, 2005, CHEMOSPHERE, V58, P1439, DOI 10.1016/j.chemosphere.2004.10.007 ELNAHHAL Y, 2000, J AGR FOOD CHEM, V48, P4791 FARMER JD, 1992, PROTEROZOIC BIOSPHER, P247 FAYAD NM, 1995, MAR POLLUT BULL, V30, P239 FOGHT JM, 1999, ENIGMATIC MICROORGAN, P527 GARCIAPICHEL F, 1996, APPL ENVIRON MICROB, V62, P3284 GAUTHIER MJ, 1992, INT J SYST BACTERIOL, V42, P568 GROTZSCHEL S, 2002, BIODEGRADATION, V13, P273 HOFFMANN L, 1996, MARINE WILDLIFE SANC, P96 HOPNER T, 1996, MARINE WILDLIFE SANC, P85 JACKSON A, 1997, J ENVIRON QUAL, V26, P1140 JAVOR BJ, 1984, MICROBIAL MATS STROM, P85 KAPLEY A, 1999, BIORESOURCE TECHNOL, V67, P241 KARSTEN U, 1996, J PHYCOL, V32, P501 KHAN NY, 1998, ENVIRON INT, V24, P239 KLEIKEMPER J, 2002, APPL ENVIRON MICROB, V68, P1516 KOHRING GW, 1989, APPL ENVIRON MICROB, V55, P348 LEE K, 1999, PURE APPL CHEM, V71, P161 LEVEN L, 2005, INT BIODETER BIODEGR, V55, P153, DOI 10.1016/j.ibiod.2004.09.004 LOVELY DR, 1997, J IND MICROBIOL BIOT, V18, P75 LUDWIG W, 1998, ELECTROPHORESIS, V19, P554 MARGESIN R, 2001, APPL MICROBIOL BIOT, V56, P650 MILLE G, 1991, FRESEN J ANAL CHEM, V339, P788 MULLER R, 1998, BIOTECHNOLOGY EXTREM, P155 MUYZER G, 1995, ARCH MICROBIOL, V164, P165 NICHOLSON CA, 2004, APPL ENVIRON MICROB, V70, P1222, DOI 10.1128/AEM.70.2.1222-1225.2004 NUBEL U, 1997, APPL ENVIRON MICROB, V63, P3327 OREN A, 1992, BIODEGRADATION, V3, P387 POLYMENAKOU PN, 2005, BIODEGRADATION, V16, P403, DOI 10.1007/s10532-004-3333-1 PRUFERTBEBOUT L, 1994, MICROBIAL MATS STRUC, P111 Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

3. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. © RADWAN SS, 1995, APPL MICROBIOL BIOT, V44, P265 RAINEY FA, 1997, INT J SYST BACTERIOL, V47, P510 RHYKERD RL, 1995, ENVIRON POLLUT, V90, P127 ROTHROCK MJ, 2005, ENVIRON MICROBIOL, V7, P593, DOI 10.1111/j.1462-2920.2004.00728.x SORKHOH N, 1992, NATURE, V359, P109 SORKHOH NA, 1993, APPL MICROBIOL BIOT, V39, P123 SORKHOH NA, 1995, J APPL BACTERIOL, V78, P194 VOGEL TM, 1996, CURR OPIN BIOTECH, V7, P311 WALKER JP, 1975, MAR BIOL, V30, P193 WARD DM, 1976, APPL ENVIRON MICROB, V31, P764 WARD DM, 1978, APPL ENVIRON MICROB, V35, P353 WARD DM, 1998, MICROBIOL MOL BIOL R, V62, P1353 WIDDEL F, 2001, CURR OPIN BIOTECH, V12, P259 WU QZ, 1996, APPL ENVIRON MICROB, V62, P4174 For pre-prints please write to: rabed@mpi-bremen.de Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa