Biodegradation of long chain alkanes in halophilic conditions by Alcanivorax sp. strain Est-02 isolated from saline soil

Abstract

In this study, through a multistep enrichment and isolation procedure, a halophilic bacterial strain was isolated from unpolluted saline soil, which was able to effectively and preferentially degrade long chain alkanes (especially tetracosane and octacosane). The strain was identified by 16S rRNA gene sequence as an Alcanivorax sp. The growth of strain Est-02 was optimized at the presence of tetracosane in different NaCl concentrations, temperatures, and pH. The consumption of different heavy alkanes was also investigated. Optimal culture conditions of the strain were determined to be as follows: 10% NaCl, temperature 25-35 °C and pH 7. Alcanivorax sp. strain Est-02 was able to use a wide range of aliphatic substrates ranging from C 14 to C 28 with clear tendency to utilize heavy chain hydrocarbons of C 24 and C 28. During growth on a mixture of alkanes (C 14-C 28), the strain consumed 60% and 65% of tetracosane and octacosane, respectively, while only about 40% of the lower chain alkanes were degraded. This unique ability of the strain Est-02 in efficient and selective biodegradation of long chain hydrocarbons could be further exploited for remediation of wax and heavy oil contaminated soils or upgrading of heavy crude oils. Comparison of the sequence of alkane hydroxylase gene (alkB) of strain Est-02 with previously reported sequences for Alcanivorax spp. and other hydrocarbon degraders, showed a remarkable phylogenetic distance between the sequence alkB of Est-02 and other alkane-degrading bacteria.

Efficacy of Bioadmendments in Reducing the Influence of Salinity on the Bioremediation of Oil-Contaminated Soil

“…Salinity can affect soil pH, ion exchange capacity, soil organic matter, and microbial biomass abundance, all of which influence the ability of the microbial community to degrade hydrocarbons in the soil (Zhang et al, 2019). Previous studies have reported higher levels of alkane degradation under saline conditions, including the use of halophilic bacteria strains and indigenous halotolerant hydrocarbon degraders (SadrAzodi et al, 2019;Akbari et al, 2021). Therefore, the observed alkane degradation in this study is likely attributed to the selection of halotolerant strains that are capable of alkane degradation.…”

“…It is important to acknowledge that the studies referenced to support higher degradation rates of alkanes and PAHs in saline soils employed various additional factors that contributed to their results. These factors included the presence of low concentrations of hydrocarbons in the soil (Wei et al, 2020;Cui et al, 2023), the isolation and selection of competent halotolerant bacterial strains capable of degradation (SadrAzodi et al, 2019;Guo et al, 2022), the immobilisation of bacteria on biochar (Song et al, 2021;Guo et al, 2022), and the use of a single hydrocarbon contaminant (Cui et al, 2023). These studies required additional material and energy inputs, which may compromise their status as sustainable and environmentally friendly green technologies.…”

Facilitating Growth of Maize (Zea mays L.) by Biostimulants: A Perspective from the Interaction between Root Transcriptome and Rhizosphere Microbiome

“…Interestingly, Shaffer et al demonstrated that Luteibacter can infect an Ascomycota and alter its functions in auxin and enzyme production Alcanivorax are alkane-degrading bacteria, and their existence in rhizosphere of Calotropis procera was verified to be involved in helping the plant to defend against pathogens Nitrosococcus are well-documented ammonia-oxidizing bacteria widely found in wastewater, soil, and rhizosphere, which convert ammonia to nitrate so that it can be utilized by plants .…”

Functional Analysis of Novel alkB Genes Encoding Long-Chain n-Alkane Hydroxylases in Rhodococcus sp. Strain CH91

“…Several bacteria including Acinetobacter , Pseudomonas , Dietzia , Rhodococcus , Geobacillus , etc. have been reported to be able to degrade long-chain n -alkanes [ 5 , 6 ]. The biodegradation of long-chain n -alkanes in these bacteria is usually initiated by the terminal oxidation of n -alkane to the corresponding alkanol, which is the key step in the n -alkane degradation pathway and catalyzed by an alkane hydroxylase.…”