by rupturing the cell walls of the cork which is composed of lignocellulose suberin 

 complex filled with air spaces. Petroleum hydrocarbons such as gasoline, kerosene^ 

 lubricating oil, crude oil, and other petroleum products are oxidized by microorganisms 

 inhabiting sea water and marine bottom sediments as well as on land. In a laboratory 

 test, samples of crude oil added to marine sediments were rapidly destroyed by the 

 hydrocarbon-oxidizing bacteria of Proactlnomyces , Actinomyces , Pseudomonas , 

 Mlcromonosporg , or Mycobacterium . Bacteria which utilize hydrocarbon might be 

 Instrumental in causing undesirable changes In petroleum products stored over water. 

 Kerosene and gasoline In storage tanks were decomposed with the formation of 

 methane and possibly ethane. When combined with air, these gases could form 

 explosive mixtures which might account for spontaneous oil fires. '° In a laboratory 

 test, neither polyethylene plastic nor neoprene was affected by either aerobic or 

 anaerobic marine bacteria; however, polyvinyl chloride plastics were susceptible to 

 bacterial decomposition according to the way in which they were plasticized. 



Sulfate-Reducing Bacteria 



The sulfate-reducing bacteria are strict anaerobes which obtain their energy 

 by the reduction of sulfates and sulfites in water In the absence of free oxygen. The 

 end product of their metabolic process Is hydrogen sulfide. These bacteria are widely 

 distributed In the marine environment and have assumed particular significance since 

 It was discovered that they are agents of deterioration of organic and inorganic 

 materials. 19,20,21,22 ZoBell found from 10,000 to 1,000,000 sulfate-reducing 

 bacteria per gram of bottom sediment from the Pacific coast of California. '^ 



In the Black Sea, oxygenated water is found from the surface down to 

 approximately 600 feet, and Is Inhabited by plants and animals. However, between 

 600 feet and the bottom at approximately 6,600 feet, the water contains large 

 quantities of hydrogen sulfide (6.04 ml/liter at a depth of 3, 300 feet), and only 

 microorganisms Inhabit this area. ^ The high content of the hydrogen sulfide does 

 not visibly inhibit the capacity of microorganisms to use organic matter and other 

 materials in their life process. They participate in the overturn of carbon, nitrogen, 

 sulfur, and phosphorus In the sea. A bacteriological examination of one gram of 

 mud taken from the deepest parts of the Black Sea floor produced 100, 000 colonies 

 of bacteria on a suitable medium. The large microbial population In the hydrogen- 

 sulfide zone consists chiefly of filamentous purple-sulfur bacteria. 23 



The aqueous hydrogen-sulfide environment is detrimental to many materials; 

 for example, it may produce the erratic behavior of steels known as "sul fide-stress 

 cracking." This is the spontaneous fracturing of steel subjected simultaneously to 

 a corrosive hydrogen-sulfide aqueous medium and a static stress less than the tensile 

 strength of the metal. 24 Polyethylene insulating compounds used In ocean telephone 

 cables are essentially impervious to sea water and oxygen; however, they can be 

 permeated by hydrogen sulfide found in ocean-bottom sediments. 25 



