Bacterial community dynamics during bioremediation of alkane- and PAHs-contaminated soil of Siri island, Persian Gulf: a microcosm study

Abstract

Studding the diversity of soil indigenous microorganisms, and monitoring effect of contaminants on microbial population, is very critical for understanding microbial activity during bioremediation and selecting successful remediation strategy.To simulate the natural environment, four microcosms were prepared by artificially contaminating clean soil with defined amounts of petroleum hydrocarbons including alkanes mixture (C 13 -C 20 ), polyaromatic hydrocarbons (PAHs) mixture (anthracene, phenanthrene, fluoranthene, pyrene and benzo (α) pyrene) and both alkanes and PAHs. Contaminants degradation and heterotrophic bacterial count were measured during a 6-month study. Copy number of alkB and C23DO genes was studied using real-time PCR, and bacterial diversity was monitored by 16S rRNA gene PCR and denaturing gradient gel electrophoresis (DGGE). Results indicated that all types of contaminants (except the five ring benzo (α) pyrene) were totally degraded after 6 months and the increase in hydrocarbon degradation rate coincided with the enhancement of total heterotrophic bacterial count in each microcosm. Real-time PCR results showed a significant increase in the copy number of both alkB and C23DO genes in alkane-and PAHs-contaminated microcosm comparing with the control microcosm, indicating selection for special hydrocarbon degraders in hydrocarbon-amended microcosms. The results of DGGE revealed that the type of contaminant in the same soil has a remarkable influence on soil bacterial community structure. Sequencing of DGGE bands suggested that most of the dominant members of the microbial community of contaminated soil are unculturable bacteria from Proteobacteria and the genus Bacillus.

Biodegradación de dos residuos de estaciones de servicio en Río Gallegos - Argentina

“…Esto pone en evidencia que la composición del Residuo 2 resulta tóxica para los microorganismos del suelo debido a su composición rica en compuestos poliaromáticos (Singh et al, 2014), característicos de nafta altamente evaporada. Muchos son los reportes que indican que los hidrocarburos poliaromáticos producen una marcada disminución de la biomasa del suelo y una inhibición de la actividad enzimática microbiana (Sakshi et al, 2019), lo que redunda en una disminución en la diversidad bacteriana (Khomarbaghi et al, 2019). Se ha demostrado que concentraciones de mezclas de estos contaminantes de 30 mg.kg -1 en suelos no generan estos efectos, pero con concentraciones de 300 mg.kg -1 o superiores se comienzan a ver efectos de disturbio de la comunidad bacteriana y de inhibición de la actividad enzimática, principalmente de los Figura 3.…”

Investigating Bacterial Communities Resistant to Heavy Metal and PAHs Pollutants in the Persian Gulf and Their Ability to Remove These Compounds (a Review)

“…Many studies have been conducted to remove heavy metals and PAHs from aquatic environment using biological adsorbents, which are considered the most appropriate methods compared to other methods [66,67]. Overall, various species of bacteria have been isolated and reported by numerous researchers in the Persian Gulf, maybe because of its high resistance to an extensive range of oil hydrocarbons and heavy metals [3,6,68]. According to mentioned abilities of bacteria, many writers have suggested the use of this method in removing oil pollution and heavy metals in aquatic environments such as the Persian Gulf [69][70][71][72][73][74].…”

Adsorption-Degradation of Polycyclic Aromatic Hydrocarbons in Soil by Immobilized Mixed Bacteria and Its Effect on Microbial Communities

“…To describe the adsorption kinetics of Phe and Pyr in the four treatments aforementioned, the obtained data were fitted by the quasi-first-order kinetic equation ( 1) and the quasi-second-order kinetic equation (2). The fitting results are shown in Figures 2 and 3, and the fitting parameters are shown in Table 3.…”

“…Polycyclic aromatic hydrocarbons (PAHs) are a type of organic compound that contains two or more benzene rings, with all carbon and hydrogen atoms located in the same plane . PAHs are of great environmental concern due to their ubiquitous occurrence, recalcitrance, bioaccumulation, detrimental biological effects, toxicity, mutagenicity, and carcinogenicity. − PAHs persist for a long time and accumulate with time in soil. They can enter the human body through food chains and endanger human health and the ecological environment. − PAHs in the soil can be removed by microbial remediation technology .…”