Microbial biodegradation

About: Microbial biodegradation is a research topic. Over the lifetime, 1647 publications have been published within this topic receiving 75473 citations.

Isolation, identification and biodegradation ability of diesel oil degrading Pseudomonas sp. strain C7 from bilge water.

Abstract: Some highly efficient diesel oil-degrading bacteria were isolated from bilge water. One isolated strain C7 was identified as Pseudomonas sp. based on its 16S rDNA gene sequence as well as various morphological, physiological and phylogenetic characteristics. The biodegradation potential and characteristics of strain C7 in various conditions were analyzed. GC-MS analysis showed that this strain could degrade most components of diesel oil, and the degradation rate was up to 75.9% after ten days incubation at the optimal condition which included a temperature of 30°C, a pH level of 7.0, initial diesel oil concentrations of 3% (v/v) and initial bacteria concentrations of 4 × 107cells/ml. Key word: Bilge water, biodegradation, diesel oil and Pseudomonas sp.

Environmental occurrence, toxicity concerns, and biodegradation of neonicotinoid insecticides

Abstract: Neonicotinoids (NEOs) are fourth generation pesticides, which emerged after organophosphates, pyrethroids, and carbamates and they are widely used in vegetables, fruits, cotton, rice, and other industrial crops to control insect pests. NEOs are considered ideal substitutes for highly toxic pesticides. Multiple studies have reported NEOs have harmful impacts on non-target biological targets, such as bees, aquatic animals, birds, and mammals. Thus, the remediation of neonicotinoid-sullied environments has gradually become a concern. Microbial degradation is a key natural method for eliminating neonicotinoid insecticides, as biodegradation is an effective, practical, and environmentally friendly strategy for the removal of pesticide residues. To date, several neonicotinoid-degrading strains have been isolated from the environment, including Stenotrophomonas maltophilia, Bacillus thuringiensis, Ensifer meliloti, Pseudomonas stutzeri, Variovorax boronicumulans, and Fusarium sp., and their degradation properties have been investigated. Furthermore, the metabolism and degradation pathways of neonicotinoids have been broadly detailed. Imidacloprid can form 6-chloronicotinic acid via the oxidative cleavage of guanidine residues, and it is then finally converted to non-toxic carbon dioxide. Acetamiprid can also be demethylated to remove cyanoimine (=N–CN) to form a less toxic intermediate metabolite. A few studies have discussed the neonicotinoid toxicity and microbial degradation in contaminated environments. This review is focused on providing an in-depth understanding of neonicotinoid toxicity, microbial degradation, catabolic pathways, and information related to the remediation process of NEOs. Future research directions are also proposed to provide a scientific basis for the risk assessment and removal of these pesticides.

Effects of microbial activity on aquatic pollutants

Abstract: Bacteria and fungi present in estuarine and marine water and sediment accomplish significant degradation of crude oil, refined oils, polychlorinated biphenyls, and organomercurials, with the rate and extent of degradation varying with species, geographic source, temperature, and other biologic and environmental parameters. Our biodegradation studies have been extended to determine if physical weathering and/or microbial degradation of oil by microorganisms present in Chesapeake Bay water and sediment produces potentially carcinogenic substances. Water and sediment from an area in Chesapeake Bay that receives heavy input of oil and from a relatively nonpolluted site have been assayed for mutagenic ability by use of the Ames method, which is a bacterial assay and is highly sensitive. Preliminary findings indicate the presence of mutagenic substances in samples collected from the polluted site. Extracts of oil subjected to microbial degradation under controlled laboratory conditions did not yield detectable mutagenic activity. In situ studies are in progress.

[Hydrocarbon-Oxidizing potential and the genes for n-alkane biodegradation in a new acidophilic mycobacterial association from sulfur blocks].

Abstract: The capacity of AGS10, a new aerobic acidophilic (growing within the pH range from 1.3 to 4.5 with the optimum at 2.0–2.5) bacterial association from sulfur blocks of the Astrakhan gas-processing complex (AGC), for oxidation of hydrocarbons of various chemical structure was investigated. A broad spectrum of normal (C10-C21) and iso-alkanes, toluene, naphthalene, and phenanthrene, as well as isoprenoids resistant to microbial degradation, pristane and phytane (components of paraffin oil), and 2,2,4,4,6,8,8,-heptamethylnonane, a branched hydrocarbon, were biodegraded under acidic conditions. Microbiological investigation revealed the dominance of mycobacteria in the AGS10 association, which was confirmed by analysis of the 16S rRNA gene clone library. In the phylogenetic tree, the 16S rRNA sequences formed a branch within the cluster of slow-growing mycobacteria, with 98% homology to the closest species Mycobacterium florentinum. Genomic DNA of AGS10 culture grown on C14-C17n-alkanes at pH 2.5 was found to contain the genes of two hydroxylase families, alkB and Cyp153, indicating their combined involvement in hydrocarbon biodegradation. The high hydrocarbon-oxidizing potential of the AGS10 bacterial association indicated that further search for the genes responsible for degradation of various hydrocarbons in acidophilic mycobacteria could be promising.