Anti-Corrosion Coating Utilizing Bacterial Precipitated Exopolysaccharides

Abstract

Disclosed is a method for inhibiting corrosion on corrosion-sensitive metal with a bacterial exopolysaccharide. Specifically, exopolysaccharides precipitated from NRRL bacterial strains B-1254, B-1355, B-1498, and B-1500 coated on low carbon steel alloy confers anti-corrosion coating to corrosion sensitive metals. Preferably with the coating, the corrosion rate for coated metal is less than 0.4 milli-inch per year.

1 . A method for inhibiting corrosion on corrosion-sensitive metal with a bacterial exopolysaccharide, the method comprising:
 culturing a bacterial strain wherein the bacterial strain is selected from strain NRRL B-1498.   precipitating a substantially pure exopolysaccharide fraction from said culture,   applying the substantially pure exopolysaccharide fraction to corrosion-sensitive metal, wherein the metal corrosion rate of the corrosion-sensitive metal having the exopolysaccharide applied thereto is inhibited.   
     
     
         2 . The method of  claim 1  wherein an iron corrosion rate of the corrosion-sensitive metal having the exopolysaccharide applied thereto is less than 0.4 mill-inches per year. 
     
     
         3 . The method of  claim 1  wherein the exopolysaccharide is precipitated from a cell-free culture fluid. 
     
     
         4 . (canceled) 
     
     
         5 . The method of  claim 1  wherein the exopolysaccharide fraction is a L fraction precipitated from strain NRRL B-1498. 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein the corrosion-sensitive metal is a low carbon steel alloy. 
     
     
         8 . The method of  claim 1 , wherein the exopolysaccharide prevents corrosion in a pure salt oxidization environment. 
     
     
         9 . The method of  claim 1  wherein the exopolysaccharide fraction is applied via spray coating. 
     
     
         10 . The method of  claim 9  wherein the exopolysaccharide fraction is applied to the corrosion-sensitive metal at a minimum thickness of approximately 50 nm. 
     
     
         11 . The method of  claim 1  wherein the exopolysaccharide fraction is applied via cast films. 
     
     
         12 . A method for inhibiting corrosion on corrosion-sensitive metal with a bacterial exopolysaccharide, the method comprising:
 coating steel with an aqueous solution of substantially pure exopolysaccharide, wherein the exopolysaccharide is precipitated from a NRRL B-1492 bacterial culture.   
     
     
         13 . (canceled) 
     
     
         14 . The method of  claim 12  wherein the exopolysaccharide fraction is a L fraction precipitated from strain NRRL B-1498. 
     
     
         15 . (canceled) 
     
     
         16 . The method of  claim 12  wherein the steel is a low carbon steel alloy. 
     
     
         17 . A steel metal alloy comprising:
 a substrate with an exterior surface; and   a protective coating positioned on said exterior surface that reduces corrosion of said exterior surface; wherein said coating comprises a exopolysaccharide coating precipitated from a bacterial culture NRRL B-1498.   
     
     
         18 . The method of  claim 17  wherein the metal alloy is a low carbon steel alloy.