by enriched through the assay featured by experiments characterized by chronological re-inoculation on new substrate, for its successive treatment, every 24 and 96 h,
respectively. This present study centralized on the effectiveness of PAHs degradation, characterization of the microbiological abundance, and pathway which provide
a holistic approach on the bioremediation of soil contaminated with PAHs.
Simarroa et al. (2013) evaluated the effect of various in situ bioremediation
treatments which entail natural attenuation, bioaugmentation, biostimulation, and
bioaugmentation on creosote-contaminated soil. Some of the parameters assessed
were evolution of bacterial communities, toxicity, creosote degradation, and microbial respiration. The result obtained indicated that the creosote reduced significantly
all the treatments, and no single variation was discovered among all the treatments.
Moreover, it was discovered that some certain PAHs were broken down to a larger
extent through biostimulation. The domination of low temperatures at an average of
8.9
C lowers the microbial creosote and the polycyclic aromatic hydrocarbon
uptake and polycyclic aromatic hydrocarbon degradation (>60%) at the completion
of the experiment while the level of toxicity remains constant through the experiment. The result obtained from the biostimulation indicated maximum microbial
biodiversity by the termination of the biodegradation process, while the composition
of all the treatment varies from all the treatments in comparison with the control
assay. It was later discovered that some of the uncultured bacteria belong to the
genera Sphingomonas, Balneimonas, Pseudomonas, Pantoea, and Flexibacter. It
was also established that Pantoea and Balneimonas possess the capability to degrade
PAH while Pseudomonas genus was the most of the species identified during the
process of creosote biodegradation. The result affirmed that some bacteria possess an
intrinsic potential to degrade the creosote without previous exposure.
Bento et al. (2003) assessed the effect of bioaugmentation, natural attenuation,
and biostimulation on the degradation of total petroleum hydrocarbons available in
the polluted soils with diesel oil. It was observed that bioaugmentation exhibits the
maximum degradation which includes heavy (C23–C40) fractions of TPH (75.2%)
and light (C12–C23) fractions (72.7%) while natural attenuation shows more activity
when compared to the biostimulation. The highest dehydrogenase activity of 3.3fold was detected from bioaugmentation of the Long Beach soil followed by 4.0-fold
by the natural attenuation of the Hong Kong soil. It was also observed that the
population of heterotopic and microorganisms that possess that capability to degrade
diesel oil was not influenced by bioremediation treatment. It was also established
that the application of inoculum of microorganism pre-selected from their own
environment gave the best approaches for the ecorestoration of soil polluted with
diesel oil.
The pollution of the soil with aromatic compounds has been identified as a serious
environmental concern which could lead to mutagenic and carcinogenic properties.
In view of this, Koul and Gauba (2014) wrote a comprehensive review on the
application of bioaugmentation for the bioremediation of heavily contaminated
soil. The authors stated that bioaugmentation has been utilized as a biotechnological
techniques for enhancement of the biodegradative potentials of polluted soil using
some microorganisms. The amendment of pre-grown microbial cultures improves
15 Bioaugmentation: A Powerful Biotechnological Techniques for Sustainable. . .
377
respectively. This present study centralized on the effectiveness of PAHs degradation, characterization of the microbiological abundance, and pathway which provide
a holistic approach on the bioremediation of soil contaminated with PAHs.
Simarroa et al. (2013) evaluated the effect of various in situ bioremediation
treatments which entail natural attenuation, bioaugmentation, biostimulation, and
bioaugmentation on creosote-contaminated soil. Some of the parameters assessed
were evolution of bacterial communities, toxicity, creosote degradation, and microbial respiration. The result obtained indicated that the creosote reduced significantly
all the treatments, and no single variation was discovered among all the treatments.
Moreover, it was discovered that some certain PAHs were broken down to a larger
extent through biostimulation. The domination of low temperatures at an average of
8.9
C lowers the microbial creosote and the polycyclic aromatic hydrocarbon
uptake and polycyclic aromatic hydrocarbon degradation (>60%) at the completion
of the experiment while the level of toxicity remains constant through the experiment. The result obtained from the biostimulation indicated maximum microbial
biodiversity by the termination of the biodegradation process, while the composition
of all the treatment varies from all the treatments in comparison with the control
assay. It was later discovered that some of the uncultured bacteria belong to the
genera Sphingomonas, Balneimonas, Pseudomonas, Pantoea, and Flexibacter. It
was also established that Pantoea and Balneimonas possess the capability to degrade
PAH while Pseudomonas genus was the most of the species identified during the
process of creosote biodegradation. The result affirmed that some bacteria possess an
intrinsic potential to degrade the creosote without previous exposure.
Bento et al. (2003) assessed the effect of bioaugmentation, natural attenuation,
and biostimulation on the degradation of total petroleum hydrocarbons available in
the polluted soils with diesel oil. It was observed that bioaugmentation exhibits the
maximum degradation which includes heavy (C23–C40) fractions of TPH (75.2%)
and light (C12–C23) fractions (72.7%) while natural attenuation shows more activity
when compared to the biostimulation. The highest dehydrogenase activity of 3.3fold was detected from bioaugmentation of the Long Beach soil followed by 4.0-fold
by the natural attenuation of the Hong Kong soil. It was also observed that the
population of heterotopic and microorganisms that possess that capability to degrade
diesel oil was not influenced by bioremediation treatment. It was also established
that the application of inoculum of microorganism pre-selected from their own
environment gave the best approaches for the ecorestoration of soil polluted with
diesel oil.
The pollution of the soil with aromatic compounds has been identified as a serious
environmental concern which could lead to mutagenic and carcinogenic properties.
In view of this, Koul and Gauba (2014) wrote a comprehensive review on the
application of bioaugmentation for the bioremediation of heavily contaminated
soil. The authors stated that bioaugmentation has been utilized as a biotechnological
techniques for enhancement of the biodegradative potentials of polluted soil using
some microorganisms. The amendment of pre-grown microbial cultures improves
15 Bioaugmentation: A Powerful Biotechnological Techniques for Sustainable. . .
377