Q.1
Read the following statements regarding bioremediation
(A) . Aerobic biodegradation of PCBs is mainly carried out by the white rot fungus, Phanerochaete and by Acinetobacter and
Alcaligenes.
(B) . Methylococcus capsulatus can convert chloro- and bromo methane to formaldehyde, dichloro- and trichloro methane to
CO? while growing on methane.
(C) . In most cases, pesticides that are cometabolized are completely degraded, hence cometabolism of a pesticide is always
good from an environmental standpoint
(D) . Burkholderia dechlorinates the pesticide 2, 4, 5-T aerobically by using oxygenase enzymes and release chloride ion
(Ch).
(E) . Reductive dechlorination is less important than oxidative dechlorination from ecological standpoint.
Choose the correct answer from the options given below:
- Statement (A) is Correct: Aerobic degradation of polychlorinated biphenyls (PCBs) is executed by the white-rot basidiomycete Phanerochaete chrysosporium (via lignin peroxidases) and bacterial strains of Acinetobacter and Alcaligenes (via the bph operon).
- Statement (B) is Correct: The methanotroph Methylococcus capsulatus utilizes soluble methane monooxygenase (sMMO) to cometabolize mono-, di-, and tri-halomethanes to formaldehyde and $\text{CO}_2$.
- Statement (D) is Correct: Burkholderia cepacia aerobically degrades 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) via oxygenases, releasing free inorganic chloride ions ($\text{Cl}^-$).
- Why (C) and (E) are Incorrect: Incomplete cometabolism (C) can yield recalcitrant dead-end metabolites more hazardous than the parent pesticide. Anaerobic reductive dechlorination (E) is of paramount ecological importance for highly chlorinated contaminants.
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