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In recent decades, human actions aimed at maintaining dominance over the earth's natural resources have endangered the ecological balance. The irreparable damage caused by oil pollution not only impacts the environment but also affects the economy and the health of living organisms. Therefore, in addition to preventive measures, it is crucial to focus on techniques for removing this type of pollution. Bioremediation, which involves the use of microorganisms like bacteria and fungi to eliminate, decompose, or reduce pollution, offers eco-friendly and cost-effective advantages. While organisms from various domains can play a role in bioremediation, fungi stand out as promising candidates. Their metabolic abilities enable them to breakdown complex molecules, making them highly effective in degrading stubborn organic matter in nature. Fungi, often referred to as mycoremediators, have been more extensively studied for bioremediation in terrestrial ecosystems compared to aquatic environments. This review explores the research conducted on fungi and bioremediation, summarizing findings and analyzing the progress in this field from the past to the present through bibliometric analysis. The results indicate that most studies concentrate on fungi isolated from soil, with Aspergillus, Penicillium, Fusarium strains being frequently reported. China, Iran, and Nigeria have published the most documents on this subject in the Scopus database. Utilizing a consortium of microorganisms is likely to yield better results than using a single strain. Overall, the use of fungi in bioremediation shows promise due to their specific metabolic characteristics. [ABSTRACT FROM AUTHOR]

Crude oil pollution can decrease the biodiversity in the marine environment. The Persian Gulf in Iran is an ecosystem rich in marine organisms that can effectively degrade crude oil. This study aimed to screen bacterial strains to degrade crude oil from the intestinal microbial flora of Mudskippers fish from the Persian Gulf. The identification of collected fish samples distinguished four diverse genera. Periophthalmus waltoni was the most common. Next, biochemical and molecular identification of isolated bacteria was performed. Some biochemical tests, such as catalase, oxidase, and motility, were done. Molecular identification was performed by polymerase chain reaction using general primers. Finally, the ability of bacterial isolates to degrade crude oil was investigated using spectrophotometric, gravimetric, gas chromatography, and FTIR methods. Bacteria identified in this study include Marinobacter hydrocarbonoclasticus, Pseudomonas aestusnigri, Thalassospira permensis, Microbacterium esteraromaticu, Oceanimonas sp, Halomonas Salaria, Halomonas beimenensis, Cobetia marina, Tenacibaculum discolor and Shewanella chilikensis. Halomonas salaria had the highest growth rate (OD= 1.6) and crude oil degradation (90%) among the studied strains. The results of our studies on five strains of T. permensis, S. chilikensis, M. hydrocarbonoclasticus, and Oceanimonas in concentrations of 1, 2.5, 4, 5.5, and 7 g/l crude oil show that with increasing concentration, crude oil reduces the ability of the strains to degradation (decrease degradation from 90 % to 20 %). Other studies have been conducted to recognize fish as an indicator of oil pollution. Still, the results of this research confirmed that crude oil pollution decreases the biodiversity in the intestinal microbial flora of these fish. The isolated bacteria can degrade crude oil and help degrade this pollution in aquatic ecosystems. By applying these bacteria, crude oil pollution in the Persian Gulf can be better managed and decreased. [ABSTRACT FROM AUTHOR]

The marine environment is a rich source of microorganisms producing bioactive compounds, like biosurfactant-producing bacteria that exhibit unique characteristics and functionalities. In this study, we examined glycolipid biosurfactants produced by bacteria that live commensally with marine organisms. We isolated a biosurfactant-producing strain identified as Cobetia marina strain F1, which displayed high hemolytic activity (27 mm), oil spreading ability (4 mm), emulsification index (40%), and decreasing surface tension to 31.3 (mN·m−1). Fourier transform infrared (FT-IR) spectroscopy revealed the glycolipid composition of the biosurfactant. Furthermore, elemental analysis utilizing CHNS and energy-dispersive X-ray spectroscopy (EDS) confirmed the biosurfactant contained carbon, hydrogen, nitrogen, sulfur, chlorine, potassium, oxygen, and additional elements. The critical micelle concentration (CMC) of the crude biosurfactant was determined to be 350 mg·L−1, at which concentration, a decrease in surface tension was observed when the biosurfactant was dissolved in distilled water. Given the presence of impurities in the biosurfactant composition, this observed CMC is considered acceptable. Furthermore, the biosurfactant exhibited significant antimicrobial activity against both Gram-positive and Gram-negative bacterial strains, with the largest zone of inhibition (ZOI) of 27 mm against Pseudomonas aeruginosa. This demonstrates the potential of the biosurfactant to serve as an alternative to novel antibiotic agents. The biosurfactant exhibited considerable inhibition of biofilm formation, disruption of preformed biofilms, and reduced enzymatic activity in bacterial cells following treatment. Moreover, the combination of the biosurfactant and F1 bacterial strain enhanced the degradation of crude oil by 86%, indicating its potential application in environmental remediation. These findings highlight the importance of investigating commensal strains capable to produce biosurfactants for applications in hydrocarbon remediation, overcoming antibiotic resistance, and biofilm disruption. [ABSTRACT FROM AUTHOR]

Phenols exhibit high solubility in water, leading to their potential to contaminate significant volumes of freshwater, wastewater, groundwater, oceans, and soil. The primary objective of this study is to isolate and identify bacterial and yeast isolates with optimal phenol degradation capabilities from Persian Gulf. Sea water and sediment samples were collected to isolate bacterial and yeast isolates, which were then evaluated for their ability to degrade phenol both in their single-cell form and when encapsulated in chitosan and alginate. The phenol-degrading strains were quantified using colony-forming unit (CFU) and most probable number (MPN) methods. The most promising microorganisms were selected and identified using phenotypic and polymerase chain reaction techniques. The selected isolates were immobilized in alginate and chitosan carriers, and their bioremediation potential was assessed at different phenol concentrations. The removal of phenol by the isolates was confirmed using Gas Chromatography. Through molecular techniques, Acinetobacter calcoaceticus K5 and Candida tropicalis YM2 were identified as the most efficient phenol-degrading strains. Acinetobacter calcoaceticus K5 exhibited the highest growth at phenol concentrations of 200 and 300 ppm, while Candida tropicalis YM2 showed optimal growth at a concentration of 700 pp. In case of Acinetobacter calcoaceticus, chitosan immobilization and a phenol concentration of 500 ppm proved to be the best conditions for phenol bioremediation. In the case of Candida tropicalis YM2, the highest percentage of phenol removal was achieved using the chitosan carrier at a concentration of 1000 ppm. Comparing the immobilized strains to their free counterparts, it was observed that the stabilized bacteria exhibited greater phenol removal efficiency, particularly at a concentration of 500 ppm, with a significant difference between the two conditions. This study demonstrates that the novel strains Acinetobacter calcoaceticus K5 and Candida tropicalis YM2 are efficient strains for the bioremediation of various phenol-contaminated seawater and this is the first report to show such rapid phenol degradation by these organisms isolated from sediment and seawater samples collected from Persian Gulf. [ABSTRACT FROM AUTHOR]

The Persian Gulf is a transit point for a lot of crude oil at the international level. The purpose of this research is to compare two methods of biostimulation and bioaugmentation for degradation of sediments contaminated with crude oil in the Persian Gulf. In this research, six types of microcosms were designed (sediments of Khark Island). Some indicators, such as the quantity of marine bacteria, enzyme activity (catalase, polyphenol oxidase, and dehydrogenase), biodiversity indices, and the percentage of crude oil degradation were analyzed during different days (0, 20, 40, 60, 80, 100 and 120). The results of this research showed that the highest quantity of heterotrophic and crude oil-degrading bacteria to the sixth microcosm (stimulation–bioaugmentation), a combination of two methods bioaugmentation and biostimulation (3.9 × 106 CFU g−1). After crude oil pollution, the activity of catalase and polyphenol oxidase increased, and the dehydrogenase enzyme decreased. Bioaugmentation microcosm has the highest activity of enzymes among all studied microcosms. Predominant bacteria in each microcosm belonged to Cellulosimicrobium, Shewanella, Alcanivorax, and Cobetia. The highest degradation of crude oil is related to the stimulation–bioaugmentation microcosm. The statistical results of this research proved that there is a significant relationship between the type of method chosen for biodegradation with the sampling time and the quantity of marine bacteria. The results of this research confirm that crude oil pollution in the Persian Gulf sediments can be reduced by choosing the proper bioremediation method. [ABSTRACT FROM AUTHOR]