Microbial Biodegradation and Bioremediation of Heavy Oil | Book Publisher International

 Heavy oil, characterised by its complex hydrocarbon composition and inherent resistance to biodegradation, represents a persistent environmental contaminant. Despite extensive industrial usage, the understanding of its biodegradability under varying environmental conditions remains limited. This study systematically investigates the biodegradation potential of heavy oil by indigenous microbial consortia derived from soil and water samples, under both aerobic and anaerobic conditions. Using gas chromatography to quantify residual hydrocarbons, it was demonstrated that aerobic soil-derived microbial communities achieve superior degradation efficiencies, with removal rates reaching up to 80.3%, significantly outperforming water-derived consortia, which attained a maximum of 52.1%. In contrast, anaerobic conditions markedly inhibit biodegradation, with maximum removal efficiencies of 43.7% and 11.1% for water- and soil-derived microbes, respectively. Correlative analyses reveal a positive association between initial microbial biomass—particularly heterotrophic and hydrocarbon-degrading bacteria—and degradation performance. The persistence of polycyclic aromatic hydrocarbons under anaerobic conditions underscores the recalcitrance of certain heavy oil fractions. These findings elucidate the pivotal roles of microbial community composition and oxygen availability in governing biodegradation dynamics, providing critical insights for optimising bioremediation strategies. Nonetheless, technological challenges persist, including incomplete mineralisation of heavy oil residues and suboptimal oxygen transfer in heterogeneous, large-scale sites. Addressing these issues will require the refinement of microbial consortia, the advancement of innovative biostimulation techniques, and the integration of complementary remediation technologies. Such developments hold substantial promise for delivering sustainable, cost-effective solutions to mitigate heavy oil pollution across diverse industrial and natural environments.

Author(s) Details

YOUNG-CHEOL CHANG
Muroran Institute of Technology, Japan.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-81-992493-6-3

Mechanisms of Biodegradation of Toxic Organic Compounds by Microorganisms, Focusing on Alkylphenol Degradation | Chapter 7 | Research Perspectives of Microbiology and Biotechnology Vol. 8

 In this chapter, the biodegradation of various toxic compounds by microorganisms has been discussed. First, the degradation characteristics of the Bacillus sp. CYR2 strain was described. Next, the isolation methods and degradation capabilities of recently studied rhizosphere microorganisms were described. Finally, the degradation of alkylphenols in a model soil using the mold Penicillium sp. CHY-2 as an example was explained, with a particular focus on alkylphenols (APs) among the compounds discussed in this chapter.　

Based on 16S rRNA gene sequence and phylogenetic analysis, the isolated strain was identified as Bacillus sp. CYR2. Degradation of various toxic compounds and growth of CYR2 strain were evaluated with 2% and 4% inoculum sizes. Among the 2% and 4% inoculum sizes, bacteria showed highest growth and toxic compound degradation at 4% inoculum size. Especially, compared to 2% inoculum size, growth of the strain CYR2 at 4% inoculum size was increased by 15.3 folds with phenanthrene, 15.1 folds with 4-secondary-butylphenol, 13.6 folds with naphthalene, 9.1 folds with phenol, and 5.4 folds with 4-tertiary-butylphenol. Strain CYR2 at 4% inoculum size showed the highest removal of phenol (84±5%), followed by 4-tertiary-butylphenol (66±3%), 4-secondary-butylphenol (63±5%) and 4-nonylphenol (57±6%). Compared with 2% inoculum size, the degradation ability of strain CYR2 with 4% inoculum size was enhanced by 3.45 times with 4-tertiary-octylphenol, and 2.53 times with 4-tertiary-butylphenol. Our results indicated that the newly isolated Bacillus sp. CYR2 can be used for in situ bioremediation of phenol and APs contaminated water.

The bioremediation of alkylphenols using rhizosphere microorganisms isolated from the roots of land plants was conducted. Three land plants were used to analyze the tolerance against petroleum hydrocarbons and alkylphenols. The plant Hosta undulata showed tolerance against petroleum hydrocarbons (500 mg/kg) and one of the alkylphenol, i.e., 4-tert-butylphenol (4-t-BP). Hence, thirty bacterial and thirteen fungal strains were isolated from the 4-t-BP contaminated soil collected from the roots of this plant. The biodegradation of APs was investigated using the isolated bacteria and fungi. Decrement in the APs was analyzed using high-pressure liquid chromatography (HPLC). Fungi showed higher 4-t-BP degradation than bacteria. Strain SB-4 (Penicillium pinophilum) showed 76.8%, and strain SB-7 (Trichoderma asperellum) showed 49.2% degradation of 4-t-BP under shaking and static conditions respectively. Apart from 4-t-BP, strain SB-7 degraded other alkylphenols such as 4-sec-butylphenol, 4-tert-octylphenol, and 4-nonylphenol. The major metabolites produced during alkylphenols degradation with strain SB-7 were determined using Gas chromatography linked with mass spectrometry (GC-MS). The results suggested that the plant Hosta undulata had tolerance against the toxic compounds, and the rhizosphere microorganisms isolated from the roots of this plant might be applied for the bioremediation of APs-contaminated soils.

The feasibility of Penicillium sp. CHY-2 isolated from pristine Antarctic soils as a degrader of micropollutant 4-t-BP in contaminated soil containing indigenous microorganisms were evaluated for the first time. The strain CHY-2 completely degraded 4-t-BP present in the artificially contaminated soil within 3 weeks. Colony-forming unit analysis was used to observe the number of fungi and bacteria present in the soil. The viable cell count of fungi was increased from day 10 to day 21 in contaminated soil in accordance with the decrease of 4-t-BP concentration. These results suggest that 4-t-BP present in contaminated soil could be degraded by strain CHY-2.

 

Author (s) Details

 

Young-Cheol Chang
Department of Applied Sciences, College of Environmental Technology, Muroran Institute of Technology, 27-1 Mizumoto, Muroran, 050-8585, Japan.

 

Please see the book here:- https://doi.org/10.9734/bpi/rpmab/v8/3209

Influence of Agro-Industrial Leachate Polluted Soil on the Compressive and Flexural Properties of Unstressed Concrete Substructure | Chapter 1 | Research and Developments in Engineering Research Vol. 9

 In conditions of compressive and flexural strengths in addition to load-carrying capabilities, this work compares the temporary behavior of factual substructures situated in cyanide-contaminated soil to those in spontaneously unpolluted soils. Agriculture, strength, transportation, building, electronics, and mining are just any of the several industrial projects that have increased on account of the ongoing rise of the human population. These, in proper sequence, exacerbate soil contamination by lowering the mechanical and tangible qualities of the soil, to a degree electrical conductivity, size density, pH, liquid content, and hardness. This results in a loss of crop difference, productivity, and soil character. The rate of deterioration hardened substructure is initiated by progress of salt crystal inside concrete pores beneath the surface layer established the chemical features of the soil and groundwater. The aim of this study was to question the effects of cassava mill discharge-polluted soils on the compressive and flexural strengths actual substructure factors. The cubes' compressive strengths were evaluated each seven days until era 84, but the beams were only put through third-point stowing flexural testing before. Concrete test specimens' compressive strength red-pink in both soil scenes, however the trend in the adulterated soil was less pronounced. Between the 7th and 28th days, the substance decreased by 2.50 to 9.47%, but it dreaming strength continuously middle from two points the 28th and 84th days, losing 9.95% (COV = 2.64%). The load-deviation curves were quadratic for the beams in the two geo-surroundings. The beams in cyanide-polluted soil wasted 34.5% of its flexural stiffness, while allure loss of load-giving capacities at the first crack and best failure were 15.8 and 20% individually. Higher degree of deterioration is sure for loaded factual substructures in similar conditions. Hence, forethought of soil chemistry is critical to determining suitable actual grade and nominal show support for durable substructural elements.

Author(s) Details:

Adekunle P. Adewuyi,
Department of Civil Engineering, University of Botswana, Gaborone, Botswana.

Please see the link here: https://stm.bookpi.org/RADER-V9/article/view/12224