Pseudomonas putida: An Environment Friendly Bacterium 135

As the chemical synthesis of 2-MC requires hazardous solvents such as benzene, microorganisms

are used. 2-MC was produced using Ralstonia eutropha H16 and P. putida KT2440 (Brämer and

Steinbüchel 2001). The manipulated strains, R. eutropha DeltaacnM (Re) OmegaKmprpC (Pp)

and P. putida DeltaacnM (Pp) OmegaKmprpC (Re), were created by inserting the 2-methylcitrate

synthase gene, causing the 2-methyl-cis-aconitate hydratase to be disrupted (acnM). Due to the

disruption of the acnM, there was an excessive generation of 2MC, which led to its build up. The

maximum concentrations attained by the stains after 144 hr of cultivation were 7.2 g L^–1, which

is equivalent to 26.5 mM, and 19.2 g L^–1, that is equivalent to 70.5 mM, respectively (Ewering

et al. 2006). Guaiacol is one of the products of depolymerization of kraft lignin along with catechol

benzoate and toluene. In recent years, more attention was diverted to convert guaiacol to a value

added product like muconic acid. P. putida KT2440 is engineered for two step the conversion of

guaiacol to muconic acid. Deletion of CatBC gene thereby blocking the catabolism to muconic and

insertion of cytochrome P450 and ferredoxin reductase gene from R. rhodochrous enabling the

conversion of guaiacol to catechol (Almqvist et al. 2021). Multiple natural enzymes in P. putida

KT2440 are capable of utilizing vanillin as a substrate. Vanillin dehydrogenase and various aldehyde

reductases are enzymes involved in the breakdown of vanillin into vanillyl alcohol and vanillic acid,

respectively (Simon et al. 2014). GN442PP 2426, which was previously modified to manufacture

vanillin from ferulic acid (Graf and Altenbuchner 2014, García-Hidalgo et al. 2020), may be a

more ideal host strain than KT2440 for the generation of VA since vanillic acid can then be further

assimilated via protocatechuate. This is because ferulic acid is converted into vanillin by genetically

engineering KT2440. P. putida EM42, a genome-reduced variety of P. putida KT2440 with superior

physiological features, was recently modified for growth on cellobiose (Dvořák). Cellobiose and

glucose can be used together in the same metabolic pathway owing to a mutant (PP_1444) that

lacks the periplasmic glucose dehydrogenase Gcd, but unfortunately the Δgcd strain suffered from

a significant growth defect. The growth defect was compensated by introduction of heterologous

glucose (Glf from Zymomonas mobilis) and cellobiose (LacY from Escherichia coli) transporters

with surprised production of pyruvate (Bujdoš et al. 2023)

8.4.5 Isoprenoid

It is a profitable molecule that has implications in the pharmaceutical, as well as the food and

beverage industries (Arendt et al. 2016). Bacteria such as P. putida can tolerate larger amounts

of isoprenoids (Mi et al. 2014). As a result, they can be utilized to satisfy an increasing demand.

P. putida is utilized in the process of biotransformation of isoprenoids in order to get oxidation

products of the plant monoterpene, limonene (Loeschcke and Thies 2015) or de novo biosynthesis

of the monoterpene geranic acid (Mi et al. 2014) or the carotenoids zeaxanthin and -carotene.

P. putida utilizes the methylerythritol 4-phosphate (MEP) pathway, whereas other bacteria utilize

the unrelated mevalonate (MVA) process to produce acetyl-CoA. P. putida KT2440 was genetically

modified to manufacture modest quantities of lycopene via the MEP route under the control of

IPTG-induced stress regulated promoters. These promoters allowed to produce measurable levels

of lycopene. The amount of lycopene that was produced by this strain increased by a factor of 50

(Hernandez-Arranz et al. 2019).

8.4.6 Long-chain Polysaturated Fatty Acids

In the treatment of cardiovascular disease, obesity and diabetes, long-chain polyunsaturated

fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), for example, are

adopted (Lorente-Cebrian et al. 2013). Both EPA and DHA were first extracted from fish and fish

oil, but both of those resources are becoming increasingly scarce (Lenihan-Geels et al. 2013). In

marine species, polyketide synthase (PKS)-like enzymes and pfa biosynthetic gene clusters are

responsible for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFA) from acyl-CoA

(Kaulmann and Hertweck, 2002, Napier, 2002, Wallis et al. 2002). pfa gene clusters are present in