Table 1: Heavy oil recovery and biodegradation cases.

Microorganism/Metabolite	Results	References
Alphaproteobacteria, gamma-proteobacteria and Bacilli.	Bacterial consortia degraded heavy crude oil from initial C37+ to light hydrocarbons ranging between C11-C27.	[50]
Biosurfactant produced by B. licheniformis R2	Enhanced heavy oil recovery by reducing ST/IFT. 37.1% additional oil was recovered.	[51]
Biosurfactant produced by B. subtilis B30	Emulsified heavy and light crude oil. The biosurfactant enhanced light oil recovery by 17-26% and heavy oil recovery by 31%.	[52]
Acinetobacter	94% biodegradation of saturated hydrocarbon fraction of crude oil after 5 days (industrial scale: 1 ton fermenter)	[53]
Oil-degrading bacteria and fungi at a wet land	oil in water content decreased from 2-10 mg/l to less than 0.2 mg/l	[54]
Mycobacterium frederiksbergense & Acinetobacter	Total Petroleum Hydrocarbons (TPH) reduction by consortium, Mycobacterium frederiksbergense and Acinetobacter of 25.1%, 22.3% and 14.5% at sterile conditions respectively and 22.8%, 21.3% and 12.35% at non-sterile conditions respectively.	[16]
Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus epidermidis, & Micrococcus luteus	P. aeruginosa SBL and B. cereus Z4B-11 degraded 70% and 50% of phenanthrene after one week of incubation, respectively.	[55]
Burkholderia.	Removal efficiencies of heavy metals from contaminated soils of 44.0% for Zn, 32.5% for Pb, 52.2% for Mn, 37.7% for Cd, 24.1% for Cu and 31.6% for As, respectively.	[56]
Burkholderia cepacia GS3C, Sphingomonas GY2B and Pandoraea pnomenusa GP3B	TPH concentration in soil was reduced by 64.4%; however, phytotoxicity and Photobacterium phosphoreum ecotoxicity was increased.	[57]
Rhodococcus	65.27±5.63% of crude oil was degraded in 9 days.	[58]
Garciaella petrolearia	42% viscosity reduction of heavy oil (2,637 cP at 50°C).	[59]
Enterobacter cloacea	76.3% maximum degradation at 0.25% (w/v) heavy crude oil concentration.	[60]
Pseudomonas & Bacillus	48% biodegradation of asphaltene by a mixed culture of five strains	[61]
Serratia, Raoultella & Ochrobactrum	The consortium reduced 37.3% of resins while, aliphatic and aromatic compounds increased by 86.8% and 6.7%, respectively.	[11]
Indigenous soil microflora	Degraded resins and asphaltenes by 41.5 & 35.0 wt% respectively within 180 days.	[62]
Bacillus, Pseudomonas aeruginosa, & Micrococcus	83 to 96% of 2500 mg/L asphaltene was degraded within 21 days at 30° C	[63]
Geobacillus	Reduced oil viscosity at 50°C by 15.4% to 23.8% at the lab scale and by 1.8% to 14.1% at the field scale.	[64]
Bacillus licheniformis and Bacillus subtilis	Biotransformed heavier hydrocarbons at heavy crude oil to lighter ones (C12 and C14). B. licheniformis AS5 recovered 16% additional oil at core flooding experiments.	[65]