Page 177 - CW E-Magazine (14-5-2024)

Special Report

A rapid wrap-up of what’s new in Operations,

Processes and Products

Bio-Transformations

aldolases from E. coli, 3-methyl-
2-oxobutanoate hydroxymethyltrans-
ferase, 2-keto-3-deoxy-L-rhamnonate
aldolase, and trans-o-hydroxybenzyli-
dene pyruvate hydratase-aldolase from
Pseudomonas putida, followed by

2-oxogroup reduction of the aldol
Biocatalytic production of litre) approaching toxicity at 200-gm adduct by ketopantoate reductase from E.
1
1,2,4-butanetriol (BTO) with per litre. There is a reference for coli and a Δ -piperidine-2-carboxylate/
1
a titre more than 100 gm per enzymes being functional even up to 300- Δ -pyrroline-2-carboxylate reductase
litre gm per litre. (ACS Sustainable Chem. from pseudomonas syringae pv. tomato
Eng., 2023; DOI: 10.1021/acssus- DSM 50315. A good number of
S. Sutiono et al have come out with a chemeng.2c07418). examples involving a total of 29 struc-
biocatalytic process for BTO in place turally diverse compounds are reported.
of the petrochemical route. BTO is used Biocatalytic synthesis of homo- (ACS Catal. 2023, 13, 5348-5357;
in pharma synthons, plasticisers, etc. chiral 2-hydroxy-4-butyrolac- DOI:10.1021/acscatal.3c00367).
These authors have selected suitable tone derivatives by tandem Effi cient biosynthesis of 5-
enzymes and have done optimisation. aldol addition and carbonyl aminolevulinic acid (ALA)
These authors even achieved a titre reduction
of 1.2 M (125-gm per litre) (S-BTO) C.J. Moreno et al have reported a bio- from glutamate via whole-cell
from 180-gm per litre D-xylose with catalytic process for chiral 2-hydroxy biocatalyst in immobilised
a yield exceeding 97%. “Intermediate acids and 2-hydroxy-4-butyrolactone engineered Escherichia coli
boosting” was done. They have further derivative, which are important for fi ne Y. Luo et al have referred to ALA
taken BTO to 1.6 M (170-gm per
and commodity chemicals. Three ste- as a natural plant growth regulator,
reoselective aldolases herbicide, insecticide, and photodyna-
and two stereocomple- mic therapy drug. It currently relies on
mentary ketoreduc- chemical synthesis, which is unsustain-
tases were used. The able and is unable to meet the increas-
procedure fi rst takes ing demand because of its low yields.
up aldol addition reac- These authors have selected hemA from
tion of 2-oxoacids to Burkholderia caryophylli and further
aldehydes using two processing and have optimised the gene

Chemical Weekly May 14, 2024 177

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