concentration and sanitary quality are acceptable, such treated soil–compost mixture
may be disposed on land, e.g., in the process of land restoration.
5.2 Fundamentals of TPH Metabolism
5.2.1 Characteristics of Petroleum Degrading
Microorganisms
To conduct a successful bioremediation, a wide knowledge about the indigenous
degrading microbial population present on the site is necessary, including abundance
and diversity as well as the optimal conditions of growth such as: energy and carbon
sources, temperature, amount of dissolved oxygen, pH, salinity, and moisture
content (Ramirez-Fuentes et al. 2002; Zhang et al. 2005; Masciandaro et al. 2013).
The most common factors limiting microbial growth are oxygen supply and
nutrient deficiency; however, other factors may also disturb remediation process.
Optimal biodegradation temperature was estimated to range between 30 and 40
C
(Zhang et al. 2005). Highly acidic as well as strongly alkaline pH values showed
inhibitive impact on the process (Ramirez-Fuentes et al. 2002); nevertheless, slightly
alkaline conditions can lead to improved hydrocarbon degradation (Masciandaro
et al. 2013). Poor water content, lower than 45% of the soil water holding capacity
(WHC), may result in decreased activity and mobility of microorganisms, while high
water content, higher than 85%, generally leads to the rise of anaerobic conditions
(Masciandaro et al. 2013). Understanding of factors limiting the microbial growth on
contaminated site and proper management are the key points in bioremediation
planning.
The main degrading agents among microorganisms are bacteria, filamentous
fungi, and yeasts. The ecological analysis of soil microbiota, based on culturedependent and culture-independent studies have revealed a dominance of three
bacterial phyla able to degrade hydrocarbons: Proteobacteria, Actinobacteria, and
Firmicutes (Fuentes et al. 2014). Among fungi also petroleum-degrading agents can
be distinguished. Hydrocarbon-degrading properties were found within genera like
Rhodotorula, Sporobolomyces, Aspergillus, Penicillium, and Lentinus (Masciandaro
et al. 2013).
Presently ca 140 bacterial strains are classified as petroleum-degrading (Thapa
et al. 2012; Masciandaro et al. 2013). Among them, the most common genera are
Pseudomonas sp., Paracoccus sp., Aeromonas sp., Moraxella sp., Beijerinckia sp.,
Flavobacteria sp., Chrobacteria sp., Nocardia sp., Corynebacteria sp.,
Acinetobacter sp., Mycobacterium sp., Modococci sp., Streptomyces sp., Bacilli
sp., Arthrobacter sp., Marinobacter sp., Alcanivorax sp., Microbulbifer sp.,
Sphingomonas sp., Micrococcus sp., Cellulomonas sp., Dietzia sp., Rhodococcus
sp., and Gordonia sp. (Wentzel et al. 2007; Thapa et al. 2012; Masciandaro et al.
2013). Some bacteria evolved specific mechanism enhancing adaptability. As
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A. Gielnik et al.
may be disposed on land, e.g., in the process of land restoration.
5.2 Fundamentals of TPH Metabolism
5.2.1 Characteristics of Petroleum Degrading
Microorganisms
To conduct a successful bioremediation, a wide knowledge about the indigenous
degrading microbial population present on the site is necessary, including abundance
and diversity as well as the optimal conditions of growth such as: energy and carbon
sources, temperature, amount of dissolved oxygen, pH, salinity, and moisture
content (Ramirez-Fuentes et al. 2002; Zhang et al. 2005; Masciandaro et al. 2013).
The most common factors limiting microbial growth are oxygen supply and
nutrient deficiency; however, other factors may also disturb remediation process.
Optimal biodegradation temperature was estimated to range between 30 and 40
C
(Zhang et al. 2005). Highly acidic as well as strongly alkaline pH values showed
inhibitive impact on the process (Ramirez-Fuentes et al. 2002); nevertheless, slightly
alkaline conditions can lead to improved hydrocarbon degradation (Masciandaro
et al. 2013). Poor water content, lower than 45% of the soil water holding capacity
(WHC), may result in decreased activity and mobility of microorganisms, while high
water content, higher than 85%, generally leads to the rise of anaerobic conditions
(Masciandaro et al. 2013). Understanding of factors limiting the microbial growth on
contaminated site and proper management are the key points in bioremediation
planning.
The main degrading agents among microorganisms are bacteria, filamentous
fungi, and yeasts. The ecological analysis of soil microbiota, based on culturedependent and culture-independent studies have revealed a dominance of three
bacterial phyla able to degrade hydrocarbons: Proteobacteria, Actinobacteria, and
Firmicutes (Fuentes et al. 2014). Among fungi also petroleum-degrading agents can
be distinguished. Hydrocarbon-degrading properties were found within genera like
Rhodotorula, Sporobolomyces, Aspergillus, Penicillium, and Lentinus (Masciandaro
et al. 2013).
Presently ca 140 bacterial strains are classified as petroleum-degrading (Thapa
et al. 2012; Masciandaro et al. 2013). Among them, the most common genera are
Pseudomonas sp., Paracoccus sp., Aeromonas sp., Moraxella sp., Beijerinckia sp.,
Flavobacteria sp., Chrobacteria sp., Nocardia sp., Corynebacteria sp.,
Acinetobacter sp., Mycobacterium sp., Modococci sp., Streptomyces sp., Bacilli
sp., Arthrobacter sp., Marinobacter sp., Alcanivorax sp., Microbulbifer sp.,
Sphingomonas sp., Micrococcus sp., Cellulomonas sp., Dietzia sp., Rhodococcus
sp., and Gordonia sp. (Wentzel et al. 2007; Thapa et al. 2012; Masciandaro et al.
2013). Some bacteria evolved specific mechanism enhancing adaptability. As
252
A. Gielnik et al.