mixture of hydrocarbons, comprising saturates, aromatics, resins, and asphaltenes in
varying proportions. Due to the toxicity and recalcitrant nature of petroleum hydrocarbons, crude oil pollution is currently considered a global environmental hazard.
While a variety of mechanisms (physical and chemical) are used to tackle such
accidental exposures, they are costly and have inherent limitations that may affect
the ecological balance. Thus, microbial biodegradation of petroleum hydrocarbons
has been generating increasing interest as a cost-effective method that causes the
least damage to the ecological balance. Hydrocarbonoclastic microbes, both bacteria
and fungi have been isolated from contaminated sites and are investigated for their
degradation potential. While bacteria have the advantage of fast turn over, they are
limited in that most species are able to utilize only a limited and often narrow range
of hydrocarbons. Fungi, on the other hand, are intrinsically harder and appear to be
more versatile in their utilization of petroleum hydrocarbons. The main challenges in
use of microbial biodegradation to tackle pollution are complete removal of all the
hydrocarbon components and obtaining adequate efficiency in the process. The need
to improve the degradation potential by microbes continues to drive the exploration
for new isolates, as well as the more recent interest in investigation of microbial
consortia. Use of microbial consortia requires an understanding of their individual
requirements as well as the interactions between them.
Keywords Bioremediation · Petroleum hydrocarbon · Crude oil · Microbial
consortia · Biofilm · Alkane hydroxylase · Monooxygenase
11.1 Introduction
Petroleum (crude oil) is a naturally occurring raw oil derived from buried biomass
over millions of years as a result of natural weathering processes such as thermal
decay and the intense pressure at the buried depths. Crude oil occurs in large
reservoirs in limited locations as a dark yellowish, brownish, or even greenish
viscous liquid, the color depending on the distinct chemical constituents. Petroleum
comprises a complex and varying mixture of hydrocarbons that fall into four broad
chemical fractions: saturates (alkanes), polyaromatic hydrocarbons (PAH), resins,
and asphaltenes, which may occur in various proportions depending on the location,
depth, and the age of the oil (Varjani 2017).
Petroleum products represent a primary energy source and an important industrial
raw material for people and recent years has seen an increased use of these products.
Crude oil is extracted by drilling and then refined by distilling to produce various
products. Petroleum products thus include crude oil as well as a variety of crude oil–
derived products such as petrol and diesel. They are also incorporated into numerous
products such as refrigerator parts.
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varying proportions. Due to the toxicity and recalcitrant nature of petroleum hydrocarbons, crude oil pollution is currently considered a global environmental hazard.
While a variety of mechanisms (physical and chemical) are used to tackle such
accidental exposures, they are costly and have inherent limitations that may affect
the ecological balance. Thus, microbial biodegradation of petroleum hydrocarbons
has been generating increasing interest as a cost-effective method that causes the
least damage to the ecological balance. Hydrocarbonoclastic microbes, both bacteria
and fungi have been isolated from contaminated sites and are investigated for their
degradation potential. While bacteria have the advantage of fast turn over, they are
limited in that most species are able to utilize only a limited and often narrow range
of hydrocarbons. Fungi, on the other hand, are intrinsically harder and appear to be
more versatile in their utilization of petroleum hydrocarbons. The main challenges in
use of microbial biodegradation to tackle pollution are complete removal of all the
hydrocarbon components and obtaining adequate efficiency in the process. The need
to improve the degradation potential by microbes continues to drive the exploration
for new isolates, as well as the more recent interest in investigation of microbial
consortia. Use of microbial consortia requires an understanding of their individual
requirements as well as the interactions between them.
Keywords Bioremediation · Petroleum hydrocarbon · Crude oil · Microbial
consortia · Biofilm · Alkane hydroxylase · Monooxygenase
11.1 Introduction
Petroleum (crude oil) is a naturally occurring raw oil derived from buried biomass
over millions of years as a result of natural weathering processes such as thermal
decay and the intense pressure at the buried depths. Crude oil occurs in large
reservoirs in limited locations as a dark yellowish, brownish, or even greenish
viscous liquid, the color depending on the distinct chemical constituents. Petroleum
comprises a complex and varying mixture of hydrocarbons that fall into four broad
chemical fractions: saturates (alkanes), polyaromatic hydrocarbons (PAH), resins,
and asphaltenes, which may occur in various proportions depending on the location,
depth, and the age of the oil (Varjani 2017).
Petroleum products represent a primary energy source and an important industrial
raw material for people and recent years has seen an increased use of these products.
Crude oil is extracted by drilling and then refined by distilling to produce various
products. Petroleum products thus include crude oil as well as a variety of crude oil–
derived products such as petrol and diesel. They are also incorporated into numerous
products such as refrigerator parts.
264
S. Jayasena and M. Perera