Capability of polychlorinated biophenyl (PCBs) degrading fungi segregated from sediments

Myco- and phyco-remediation of polychlorinated biphenyls in the environment: a review

Polychlorinated biphenyls (PCBs) are toxic organic compounds and pose serious threats to environment and public health. PCBs still exist in different environments such as air, water, soil, and sediments even on ban. This review summarizes the phyco- and myco-remediation technologies developed to detoxify the PCB-polluted sites. It was found that algae mostly use bioaccumulation to biodegradation strategies to reclaim the environment. As bio-accumulator, Ulva rigida C. Agardh has been best at 25 ng/g dry wt to remove PCBs. Evidently, Anabaena PD-1 is the only known PCB degrading alga and efficiently degrade Aroclor 1254 and dioxin-like PCBs up to 84.4% and 37.4% to 68.4%, respectively. The review suggested that factors such as choice of algal strains, response of microalgae, biomass, the rate of growth, and cost-effective cultivation conditions significantly influence the remediation of PCBs. Furthermore, the Anabaena sp. linA gene of Pseudomonas paucimobilis Holmes UT26 showed enhanced efficiency. Pleurotus ostreatus (Jacq.) P. Kumm is the most efficient PCB degrading fungus, degrading up to 98.4% and 99.6% of PCB in complex and mineral media, respectively. Combine metabolic activities of bacteria and yeast led to the higher detoxification of PCBs. Fungi-algae consortia would be a promising approach in remediation of PCBs. A critical analysis on potentials and limits of PCB treatment through fungal and algal biosystems have been reviewed, and thus, new insights have emerged for possible bioremediation, bioaccumulation, and biodegradation of PCBs.

Solubilization and degradation of polychlorinated biphenyls (PCBs) by naturally occurring facultative anaerobic bacteria

A combination of solubilization and degradation is essential for the bioremediation of environments contaminated with complex polychlorinated biphenyls (PCB) mixtures. However, the application of facultative anaerobic microorganisms that can both solubilize and breakdown hydrophobic PCBs in aqueous media under both anaerobic and aerobic conditions, has not been reported widely. In this comprehensive study, four bacteria discovered from soil and sediments and identified as Achromobacter sp. NP03, Ochrobactrum sp. NP04, Lysinibacillus sp. NP05 and Pseudomonas sp. NP06, were investigated for their PCB degradation efficiencies. Aroclor 1260 (50 mg/L), a commercial and highly chlorinated PCB mixture was exposed to the different bacterial strains under aerobic, anaerobic and two stage anaerobic-aerobic conditions. The results confirmed that all four facultative anaerobic microorganisms were capable of degrading PCBs under both anaerobic and aerobic conditions. The highest chlorine removal (9.16 ± 0.8 mg/L), PCB solubility (14.7 ± 0.93 mg/L) and growth rates as OD₆₀₀ (2.63 ± 0.22) were obtained for Lysinibacillus sp. NP05 under two stage anaerobic-aerobic conditions. The presence of biosurfactants in the culture medium suggested their role in solubility of PCBs. Overall, the positive results obtained suggest that high PCB hydrolysis can be achieved using suitable facultative anaerobic microorganisms under two stage anaerobic-aerobic conditions. Such facultative microbial strains capable of solubilization as well as degradation of PCBs under both anaerobic and aerobic conditions provide an efficient and effective alternative to commonly used bioaugmentation methods utilizing specific obligate aerobic and anaerobic microorganisms, separately.

Assessing the ability of white-rot fungi to tolerate polychlorinated biphenyls using predictive mycology

The aim of the present study was to assess the ability of different white-rot fungi to tolerate polychlorinated biphenyls (PCBs) using predictive mycology, by relating fungal growth inhibition to ligninolityc enzyme secretion. Fungal strains were grown in the presence of PCBs in solid media and their radial growth values were modelled through the Dantigny-logistic like function in order to estimate the time required by the fungal colonies to attain half their maximum diameter. The principal component analysis (PCA) revealed an inverse correlation between strain tolerance to PCBs and the laccase secretion over time, being laccase production closely associated with fungal growth capacity. Finally, a PCA was run to regroup and split between resistant and sensitive fungi. Simultaneously, a function associated with a model predicting the tolerance to PCBs was developed. Some of the assayed isolates showed a promising capacity to be applied in PCB bioremediation. Abbreviations: Polychlorinated biphenyls (PCBs), white-rot fungi (WRF).

Bioremediation of long-term PCB-contaminated soil by white-rot fungi

The objective of this work was to test the PCB-degrading abilities of two white-rot fungi, namely Pleurotus ostreatus and Irpex lacteus, in real contaminated soils with different chemical properties and autochthonous microflora. In addition to the efficiency in PCB removal, attention was given to other important parameters, such as changes in the toxicity and formation of PCB transformation products. Moreover, structural shifts and dynamics of both bacterial and fungal communities were monitored using next-generation sequencing and phospholipid fatty acid analysis. The best results were obtained with P. ostreatus, which resulted in PCB removals of 18.5, 41.3 and 50.5% from the bulk, top (surface) and rhizosphere, respectively, of dumpsite soils after 12 weeks of treatment. Numerous transformation products were detected (hydoxylated and methoxylated PCBs, chlorobenzoates and chlorobenzyl alcohols), which indicates that both fungi were able to oxidize and decompose the aromatic moiety of PCBs in the soils. Microbial community analysis revealed that P. ostreatus efficiently colonized the soil samples and suppressed other fungal genera. However, the same fungus substantially stimulated bacterial taxa that encompass putative PCB degraders. The results of this study finally demonstrated the feasibility of using this fungus for possible scaled-up bioremediation applications.

Promoting Behavior of Fungal Degradation Polychlorinated Biphenyl by Maifanite

Biotransformation of persistent organic pollutants (POPs) may be affected by many factors such as biostimulation and bioaugmentation whether beneficial or not. Served as natural healthy medical stone, feed additive and also filters for their adsorption capability in water purification function, was used widely in China. In this paper, PCB 118 was selected as typical polychlorinated biphenyl to study maifanite additive influence on the degradating efficiency of marine fungi for POPs. The results of controlled trials by two penicillium fungus showed thatthe degradation rates of PCB 118 were higher with maifanite as promoting additive than mediums without maifanite. Significant differences were found in further analysis of zeta potential of maifanite in solutions from pH 2 to pH 9 suggesting different adsorption capability of maifanite at different pH levels.