Identifying and sequencing a Mycobacterium sp. strain F4 as a potential bioremediation agent for quinclorac

Abstract

Quinclorac is a widely used herbicide in rice filed. Unfortunately, quinclorac residues are phytotoxic to many crops/vegetables. The degradation of quinclorac in nature is very slow. On the other hand, degradation of quinclorac using bacteria can be an effective and efficient method to reduce its contamination. In this study, we isolated a quinclorac bioremediation bacterium strain F4 from quinclorac contaminated soils. Based on morphological characteristics and 16S rRNA gene sequence analysis, we identified strain F4 as Mycobacterium sp. We investigated the effects of temperature, pH, inoculation size and initial quinclorac concentration on growth and degrading efficiency of F4 and determined the optimal quinclorac degrading condition of F4. Under optimal degrading conditions, F4 degraded 97.38% of quinclorac from an initial concentration of 50 mg/L in seven days. Our indoor pot experiment demonstrated that the degradation products were non-phytotoxic to tobacco. After analyzing the quinclorac degradation products of F4, we proposed that F4 could employ two pathways to degrade quinclorac: one is through methylation, the other is through dechlorination. Furthermore, we reconstructed the whole genome of F4 through single molecular sequencing and de novo assembly. We identified 77 methyltransferases and eight dehalogenases in the F4 genome to support our hypothesized degradation path.

Gene inversion potentiates bacterial evolvability and virulence

“…Though some sequences may naturally defy the average GC skew pattern over short lengths due to functional constraints, this pattern is highly robust over extended lengths. Furthermore, the published GC skew profiles of a variety of bacterial species show numerous local GC skew inversions, suggesting that GC skew analysis can reveal a large number of natural inverted regions 32 – 34 . Therefore, gene inversion models are testable via the GC skew method.…”

Review on the Discovery of Novel Natural Herbicide Safeners

“…70 Quinclorac is a synthetic auxin herbicide extensively used in rice fields, but the phytotoxicity of it noticeably depresses the yield and quality of crops. 77 Quinclorac is equally poisonous to tobacco seedlings when used for weed control in tobacco production. Zheng et al proved that spraying with brassinolide (75 mL/ha) reduced the inhibition rate of leaf width (decrease 9.1% and 22.9%), leaf length (decrease 1.6% and 11%), and plant height (decrease 23.8% and 0.6%) on 30-and 60-day-old subsequent tobacco by quinclorac residues from rice fields.…”

“…Quinclorac is a synthetic auxin herbicide extensively used in rice fields, but the phytotoxicity of it noticeably depresses the yield and quality of crops . Quinclorac is equally poisonous to tobacco seedlings when used for weed control in tobacco production.…”

Isolation, Screening, and Degradation Characteristics of a Quinclorac-Degrading Bacterium, Strain D, and Its Potential for Bioremediation of Rice Fields Polluted by Quinclorac

“…Li et al showed that 3-chloro-7-hydroxyquinine-8-carboxylic acid and 7-chloro-3-hydroxyquinine-8-carboxylic acid were degradation products of Mycobacterium sp. strain F4 and were nonphytotoxic to tobacco ( 19 ). Lang et al screened Streptomyces sp.…”