Lower expression levels of proteins that confer relevant properties, such as remediation of toxic xenobiotics, increased resistance and accumulation of heavy metals, and faster degradation of a variety of pesticides, are the bottleneck to soil health restoration using genetically engineered microbes. Critical discussion has been had on the application of CRISPR Cas-based systems in phytoremediation and endophytic microorganisms in pesticide remediation. Although the use of cutting-edge gene-editing tools like the CRISPR Cas system, Zinc Finger nucleases (ZFN), and transcriptional activator-like effector nucleases (TALEN) has recently received a lot of attention, further investigation of research activities utilizing these molecular tools is still required in the direction of more toxic waste remediation research.

1. RECENT ADVANCEMENT IN
GENETICALLY
ENGINEERED MICROBES
TO IMPROVE SOIL
FERTILITY
G U N J I T S E T I A
A S U 2 0 1 9 0 1 0 1 0 0 0 2 2
S E M E S T E R 8
S C H O O L O F B I O S C I E N C E

2. INTRODUCTION
Healthy soil is defined by functional and ecological balance
of soil properties such as porosity, moisture, structure, etc.
Chemical factors include organic matter, nutrients,
Carbon and Nitrogen
Biological factors include microbial diversity, soil
respiration, and microbial biomass.

3. MECHANISM: SOIL PLANT-MICROBIAL
NETWORK
The most diversified habitat, where plants and bacteria interact and play a key
role in ecosystem functioning, is the rhizosphere zone.
All plants in the ecosystem gain from plant-microbe interaction, which also
boosts productivity.
The sub-surface world is favored by a variety of mechanisms, including microbial
interactions, exudate production by plant roots, genetic exchange between
unicellular and multicellular species, and nutrient modification and exchange.

4. APPLICATION OF
MICROBIAL INOCULANTS IN
AGRO-ECOSYSTEM
• Microbial inoculants are referred to
as "plant stimulators" due to their
good effects on agricultural crop
productivity.
• The interaction between the host
plant and its microbiome is
important for plant growth because
bacteria can impact a plant's
development from germination
through flowering.

5. ROLE OF MICROORGANISMS IN SOIL HEALTH
IMPROVEMENT
Soil microorganisms
actively engineer the soil to
prepare it for plant growth,
by making nutrients
available and producing the
essential growth regulators.
To achieve sustainable
plant growth, the use of
rhizosphere bacteria to
enhance soil fertility rather
than artificial fertilizers has
been suggested.
The soil microbiome of
high-quality crops is made
up of synthetic microbial
consortia (SMC), which
were created to enhance
plant development and
quality.

6. MICROBIAL XENOBIOTIC DEGRADATION
• Metabolites can be divided into many categories, such as biotransformed intermediates,
xenobiotic degradation intermediates, and even rhizobacteria-produced plant growth
promoters.
• In attempts to enhance soil health, the idea of Plant growth promoting rhizobacteria
(PGPR) capable of degrading xenobiotics.
• Rhizobacteria are involved in rhizoremediation, phenomenon of enhancing soil health
using root-associated microbes, which involves the removal of xenobiotics from the roots
of plants even while producing substances that aid in plant growth.
• Rhizobacteria concurrently remediate soil and improve nitrogen and phosphate
availability to plants, eventually assisting in soil health and plant growth .

7. BIOENGINEERING OF MICROORGANISMS
FOR SOIL HEALTH RESTORATION BY
REMEDIATION
• GMOs can be created using a variety of molecular techniques,
including biolistic transformation, electroporation, conjugation,
horizontal transfer of bacterial DNA, molecular cloning, and
protoplast transformation.
• The time needed for cleanup is reduced by the transfer and
production of novel genes with high degrading capacity.
• By expressing genes contained in the bacterial plasmid,
engineered microorganisms may repair a number of chemicals
including toluene, octane, naphthalene, salicylate, and xylene.

8. CHALLENGES AND
SOLUTIONS IN
BIOENGINEERING
MICROBES

9. CONCLUSION
Lower expression levels of proteins that confer relevant properties, such as remediation of
toxic xenobiotics, increased resistance and accumulation of heavy metals, and faster
degradation of a variety of pesticides, are the bottleneck to soil health restoration using
genetically engineered microbes. Critical discussion has been had on the application of
CRISPR Cas-based systems in phytoremediation and endophytic microorganisms in
pesticide remediation. Although the use of cutting-edge gene-editing tools like the CRISPR
Cas system, Zinc Finger nucleases (ZFN), and transcriptional activator-like effector
nucleases (TALEN) has recently received a lot of attention, further investigation of research
activities utilizing these molecular tools is still required in the direction of more toxic waste
remediation research.

10. REFERENCES
• Hernandez‐Raquet G, Durand E, Braun F, et al. Impact of microbial diversity depletion on
xenobiotic degradation by sewage‐activated sludge. Environ Microbiol Rep. 2013;5(4):588–
594
• Bharadwaj A Bioremediation of xenobiotics: an eco-friendly cleanup approach. In Parmar, V
S, Malhotra, P, and Mathur, D(eds).,: Green chemistry in environmental sustainability and
chemical education. Singapore: Springer; 2018. p. 1–13.
• Rebello S, Sivaprasad MS, Anoopkumar AN, et al. Cleaner technologies to combat heavy
metal toxicity. J Environ Manage. 2021;296:113231 doi: 10.1016/j.jenvman.2021.113231.
• Rashid MI, Mujawar LH, Shahzad T, et al. Bacteria and fungi can contribute to nutrients
bioavailability and aggregate formation in degraded soils. Microbiol Res. 2016;183:26–41.