MEOR agents Microbes Product Possible application
  Bacillus sp. Cells and EPS (mainly
exopolysaccharides)
Selective plugging of oil
depleted zones and
wettability angle alteration
Leuconostoc
Xanthomonas
Surfactants Acinetobacter Emulsan and alas an  
  Bacillus sp. Surfactin, rhamnolipid,
lichenysin
Emulsification and deemulsification
through
reduction of interfacial
tension
Pseudomonas Rhamnolipid, glycolipids
Rhodococcus sp. Viscosin and trehaloselipids
  Arthrobacter   Injectivity profile and
viscosity modification,
selective plugging
Biopolymers Xanthomonas sp. Xanthan gum
  Aureobasidium sp. Pullulan
Bacillus sp. Levan
Alcaligenes sp. Curdlan
Leuconostoc sp. Dextran
Sclerotium sp. Scleroglucan
solvents Clostridium,
Zymomonas and
Klebsiella
Acetone, butanol, propan-
2-diol
Rock dissolution for
increasing permeability, oil
viscosity reduction
Acids Clostridium Propionic and butyric acids Permeability increase,
emulsification
  Enterobacter
Mixed acidogens
Gases Clostridium Methane and hydrogenc Increased pressure, oil
swelling, reduction of
interfacial section and
viscosity, increase
permeability
  Enterobacter
Methanobacterium
Table 1: Possible applications of biosurfactants produced by microorganisms in Microbial enhanced oil recovery (MEOR) [25].