Manual of microbiological methods

https://www.scielo.cl/pdf/ejb/v19n5/art_08.pdf

Natural carriers in bioremediation: A review

Nowadays, pesticides are widely used in preventing and controlling the diseases and pests of crop, but at the same time pesticide residues have brought serious harm to human's health and the environment It is an important subject to study microbial degradation of pesticides in soil environment in the field of internationally environmental restoration science and technology This paper summarized the microbial species in the environment, the study of herbicide and pesticides degrading bacteria and the mechanism and application of pesticide microbial degrading bacteria Cypermethrin and other pyrethroid pesticides were used widely currently, while they were difficult to be degraded in the natural conditions, and an intermediate metabolite, 3-phenoxy benzoic acid would be produced in the degradation process, causing the secondary pollution of agricultural products and a series of problems Taking it above as an example, the paper paid attention to the degradation process of microorganism under natural conditions and factors affecting the microbial degradation of pesticide In addition, the developed trend of the research on microbial degradation of pesticide and some obvious problems that need further solution were put forward

https://www.mdpi.com/1420-3049/23/9/2313/pdf

Microbial Degradation of Pesticide Residues and an Emphasis on the Degradation of Cypermethrin and 3-phenoxy Benzoic Acid: A Review.

Pyrethroid insecticides have been used to control pests in agriculture, forestry, horticulture, public health and for indoor home use for more than 20 years. Because pyrethroids were considered to be a safer alternative to organophosphate pesticides (OPs), their applications significantly increased when the use of OPs was banned or limited. Although pyrethroids have agricultural benefits, their widespread and continuous use is a major problem as they pollute the terrestrial and aquatic environments and affect non-target organisms. Since pyrethroids are not degraded immediately after application and because their residues are detected in soils, there is an urgent need to remediate pyrethroid-polluted environments. Various remediation technologies have been developed for this purpose; however, bioremediation, which involves bioaugmentation and/or biostimulation and is a cost-effective and eco-friendly approach, has emerged as the most advantageous method for cleaning-up pesticide-contaminated soils. This review presents an overview of the microorganisms that have been isolated from pyrethroid-polluted sites, characterized and applied for the degradation of pyrethroids in liquid and soil media. The paper is focused on the microbial degradation of the pyrethroids that have been most commonly used for many years such as allethrin, bifenthrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, fenpropathrin, fenvalerate and permethrin. Special attention is given to the bacterial strains from the genera Achromobacter, Acidomonas, Bacillus, Brevibacterium, Catellibacterium, Clostridium, Lysinibacillus, Micrococcus, Ochrobactrum, Pseudomonas, Serratia, Sphingobium, Streptomyces and the fungal strains from the genera Aspergillus, Candida, Cladosporium and Trichoderma, which are characterized by their ability to degrade various pyrethroids. Moreover, the current knowledge on the degradation pathways of pyrethroids, the enzymes that are involved in the cleavage of pesticide molecules, the factors/conditions that influence the survival of strains that are introduced into soil and the rate of the removal of pyrethroids are also discussed. This knowledge may be useful to optimize the environmental conditions of bioremediation and may be crucial for the effective removal of pyrethroids from polluted soils.

/pdf/pyrethroid-degrading-microorganisms-and-their-potential-for-3q5scw772k.pdf

Pyrethroid-Degrading Microorganisms and Their Potential for the Bioremediation of Contaminated Soils: A Review.

Ecotoxicity of phenol and cresols to aquatic organisms: A review.

A bacterium capable of utilizing pyrethroid pesticide cypermethrin as sole source of carbon was isolated from soil and identified as a Micrococcus sp. The organism also utilized fenvalerate, deltamethrin, perimethrin, 3-phenoxybenzoate, phenol, protocatechuate and catechol as growth substrates. The organism degraded cypermethrin by hydrolysis of ester linkage to yield 3-phenoxybenzoate, leading to loss of its insecticidal activity. 3-Phenoxybenzoate was further metabolized by diphenyl ether cleavage to yield protocatechuate and phenol as evidenced by isolation and identification of metabolites and enzyme activities in the cell-free extracts. Protocatechuate and phenol were oxidized by ortho-cleavage pathway. Thus, the organism was versatile in detoxification and complete mineralization of pyrethroid cypermethrin

Biodegradation of cypermethrin by Micrococcus sp. strain CPN 1.

The Bacillus sp. strain PHN 1 capable of degrading p-cresol was immobilized in various matrices namely, polyurethane foam (PUF), polyacrylamide, alginate and agar. The degradation rates of 20 and 40 mM p-cresol by the freely suspended cells and immobilized cells in batches and semi-continuous with shaken cultures were compared. The PUF-immobilized cells achieved higher degradation of 20 and 40 mM p-cresol than freely suspended cells and the cells immobilized in polyacrylamide, alginate and agar. The PUF- immobilized cells could be reused for more than 35 cycles, without losing any degradation capacity and showed more tolerance to pH and temperature changes than free cells. These results revealed that the immobilized cell systems are more efficient than freely suspended cells for degradation of p-cresol.

Biodegradation of p-cresol by immobilized cells of Bacillus sp. strain PHN 1

A bacterium capable of utilizing p-cresol as sole source of carbon and energy was isolated from soil and identified as a Bacillus species. The organism also utilized phenol, o-cresol, m-cresol, 4-hydroxybenzoic acid, and gentisic acid as growth substrates. The organism degraded p-cresol to 4-hydroxybenzoic acid, which was further metabolized by a gentisate pathway, as evidenced by isolation and identification of metabolites and enzyme activities in the cell-free extract. Such a bacterial strain can be used for bioremediation of environments contaminated with phenolic compounds.

Biodegradation of p-cresol by Bacillus sp. strain PHN 1.

http://www.scielo.br/pdf/bjm/v46n3/1678-4405-bjm-46-3-667.pdf

Biodegradation of cypermethrin by immobilized cells of Micrococcus sp. strain CPN 1

A bacterium capable of degrading herbicide, pendimethalin, was isolated from the contaminated soil by enrichment culture technique and identified as Bacillus circulans. The organism grew on pendimethalin (1 g/L) as the sole source of carbon and accumulated 6-aminopendimethalin and 3,4-dimethyl 2,6-dinitroaniline as metabolites in the culture medium. The cell-free extract of B. circulans grown on pendimethalin contained the activities of pendimethalin nitroreductase and pendimethalin mixed function oxidase. The results suggest that the bacterium degraded pendimethalin by nitroreduction to 6-aminopendimethalin and by oxidative dealkylation to 3,4-dimethyl 2,6-dinitroaniline and pentane, which was utilized as the source of carbon and energy for growth.

/pdf/biodegradation-of-pendimethalin-by-bacillus-circulans-5g1u6u1esx.pdf

Veena B. Megadi

Papers

Biodegradation of cypermethrin by Micrococcus sp. strain CPN 1.

Biodegradation of p-cresol by immobilized cells of Bacillus sp. strain PHN 1

Biodegradation of p-cresol by Bacillus sp. strain PHN 1.

Biodegradation of cypermethrin by immobilized cells of Micrococcus sp. strain CPN 1

Biodegradation of pendimethalin by Bacillus circulans.