Pseudomonas putida

Parathion

Chlorpyrifos

Benzene

Toluene

p-Xylene

Phenyl urea

Methyl parathion

Trichloro propane

Phenol

c

-

HCH

Carbofuran

β

-

cypermethrin

s

-

Triazine

PAH

Naphthalene

Ethylene

Mcl

PHA

Scl

PHA

methylcitric

acid

FDCA

Isoprenoid

Lc

PUFA

n

-

Butanol

PHBA

Enzymes

Pesticides

Value added products

Figure 8.1. Utilization of Pseudomonas putida for the degradation of pesticides and production of value-added

products, PAH-Polycyclic aromatic hydrocarbons, c-HCH-c Hexachlorocyclohexane, mcl-PHA, medium chain length

polyhydroxyalkanoates, short chain length polyhydroxyalkanoates, FDCA-2,5 furandicarboxyalic acid, Lc-PUFA-long chain

polyunsaturated fatty acid, PHBA-para-Hydroxy benzoic acid.

126

Bioremediation for Sustainable Environmental Cleanup

The purpose of genetic improvement would be to develop non-growing but metabolically active

sedentary cells that would reroute the metabolic fluxes away from growth and towards product

formation. However, when it comes to products such as recombinant proteins that are intimately

related to the process of growth, it could be challenging to identify the genes that need to be

knocked-out or knocked-in in order to achieve the phenotype that is desired. In order to get around

the challenge, inverse metabolic engineering is the best option. Inverse metabolic engineering is the

process of elucidating a metabolic engineering technique through the identification, construction

or calculation of a desired phenotype, the identification of the genetic or specific environmental

elements conferring that the phenotype, and the intentional genetic or environmental alteration of

another strain or organism to give that phenotype. Inverse Metabolic Engineering (IME) is divided

into three steps:

i. Choosing or creating strains with the desired phenotype.

ii. Investigating the impact of genetic and environmental factors on the phenotype.

iii. Transferring the phenotype to a different organism.

An ideal balance between phenotypic expression and cell viability is essential since genes are

being overexpressed. The expression of several enzymes should be balanced (Koffas et al. 2003,

Pitera et al. 2007). All the enzymes involved in a pathway must work together. An imbalance

expression leads to accumulation of intermediate metabolites, potentially impairing cell viability.

This chapter will briefly discuss y how genetic modifications can be made in microbial cells

to achieve the desired phenotypic expression. Some prior knowledge about the pathways and the

metabolites is important prerequisite.

The applications of Pseudomonas spp. described in this chapter are divided into two parts.

To begin with, it entails the use of engineered microbes to degrade pollutants in the environment.

Pesticides of the class organophosphate and others are discussed here, including Benzene/

toluene/p-xylene (BTX), phenylurea, methyl parathion and cadmium; 1,2,3-trichloropropane;

phenol; chlorpyrifos; carbofuran; c-hexachlorocyclohexane (c-HCH) or lindane; S-triazines;

polycyclic aromatic hydrocarbons (PAHs); Diuron; Naphthol. Second, it includes ethylene,

polyhydroxyalkanoate, 2-methylcitric acid, isoprenoid, long-chain polyunsaturated fatty acids,

n-butanol, para-hydroxyl benzoic acid, and enzyme production using pollutants as a substrate

(Figure 8.1). Many conventional chemical synthesis methods rely on depleting petroleum as a

prerequisite. As a result, microorganisms are being used in the clean and green synthesis of a wide

range of petroleum products.