Low density polythene (LDPE) is the most widely used packaging material primarily because of its excellent mechanical properties, barrier properties against water, light weight, low cost and high energy effectiveness. LDPE to biological attack was believed to be contributed by the hydrophobic carbon backbone and high molecular weight of the polymer. Thus, over the years, the rapid biodegradation of plastic has been a subject of interest in the waste management problem. Each year, an estimated 500 billion to 1 trillion plastic bags are consumed worldwide. After their use, these packaging materials are dumped in landfills leading to pollution since they are non-biodegradable under natural environmental conditions

1. Presentation Topic : Biodegradation
Of Plastic By Pseudomonas putida
Presented by,
Miss AMRITHA S R
BSc BIOTECHNOLOGY
FACULTY OF LIFE SCIENCES
JAGADGURU SRI SHIVARATHREESHWARA ACADEMY OF HIGHER EDUCATION AND RESEARCH
MYSURU
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4th May 2019

2. Overview
Introduction
Pseudomonas putida
Steps involved in degradation
Disadvantages
Current research
Conclusions
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3. INTRODUCTION
Low density polythene (LDPE) is the most widely used packaging material
primarily because of its excellent mechanical properties, barrier properties
against water, light weight, low cost and high energy effectiveness.
LDPE to biological attack was believed to be contributed by the hydrophobic
carbon backbone and high molecular weight of the polymer. Thus, over the
years, the rapid biodegradation of plastic has been a subject of interest in the
waste management problem.
Each year, an estimated 500 billion to 1 trillion plastic bags are consumed
worldwide. After their use, these packaging materials are dumped in landfills
leading to pollution since they are non-biodegradable under natural
environmental conditions
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4. PSEUDOMONAS PUTIDA
Pseudomonas putida is a gram-negative, rod-shaped bacteria
which undergoes aerobic metabolism.
It is normally found in terrestrial and aquatic environments
where oxygen is abundant.
P.putida is well known for being one of the most metabolically
diverse organisms capable of breaking down both natural
organic molecules as well as industrial compounds such as
toluene and styrene.
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5. Steps involved in degradation
Bio-deterioration defines the action of microbial
communities and other decomposer organisms
responsible for the physical and chemical
deterioration that resulted in a superficial
degradation that modifies the mechanical,
physical and chemical properties of the plastic.
Bio-fragmentation refers to the catalytic actions
that cleave polymeric plastics into oligomers,
dimers or monomers by ecto-enzymes or free-
radicals secreted by microorganisms.
Assimilation characterizes to the integration of
molecules transported in the cytoplasm in the
microbial metabolism.
Mineralisation refers to the complete
degradation of molecules that resulted in the
excretion of completely oxidized metabolites
(CO2, N2, CH4, H2O).
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6. Factors explored for a better biodegradation of
polymer plastics
(i) by using surface active agents or inducing the microorganism to
produce surfactant to allow better attachment of microorganisms on
the polymer surface,
(ii) by blending the polymers with biodegradable synthetic polymers
such as polylactic acid or polycaprolactum
(iii) by culturing those microorganisms that can efficiently degrade
the plastics (bio-addition) and
(iv) by addition of nutrients that may be limiting in the environment
(bio-stimulation).
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7. Disadvantages
A 2005 research article stated that Pseudomonas putida is associated with
clinical infections in pre-mature babies. Babies that were admitted into
Special Care Nursery (SCN) were fed through catheters. These catheters
went through a heparin flush procedure in order to keep the pathway clear
for fluids to enter the body. During this procedure, the environment
conditions within the tube allowed P. putida to grow. This growth of bacteria
caused bloodstream infections within the baby. Although heparin has
antibiotic activity, P. putida is resistant and is able to grow.
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8. Current Research
In a recent study, Pseudomonas putida strains were compared to
each other to determine the phylogenetic relationships. Because
the Pseudomonas putida strain KT2440 genome is fully
sequenced it serves as a standard reference to compare with
other Pseudomonas putida strains.
They carried out a study that assessed the utility
of Pseudomonas putida strain KT2440-based high-density DNA
microrarrays for transcriptomics studies of DSM 6125, DSM
3931, DSM 291, and S12, along with other non-sequenced
strains.
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9. Concluding remarks and perspectives
 For the last 30 years, scientists are trying to develop some alternative ways where they
can use microbes to degrade these long chain synthetic polymers into their respective
monomers. Until now, very few evidences are available where scientists were able to
develop some alternative ways to enhance the mode of degradation and make it faster.
 Nature-like experiments are difficult to realize in laboratory due to the great number of
parameters occurring during the biogeochemical recycling .
 To date, most of the knowledge on the microbial ability to degrade synthetic plastics is
based on few bacteria able to grow on culture media, that represent <0.1% of the total
bacteria.
 Hence, the great natural source of high diversity of microorganisms is not fully exploited.
By using -omics technologies (genomic, transcriptomic, proteomic, metabolomics), it is
now possible to discover new non-culturable microorganisms involved in plastic
colonization and degradation, and explore the new properties of microorganisms that
arise from the interplay of genes, proteins, other macromolecules, small molecules, and
the environment.
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10. Citations
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3460136/
https://oceans.taraexpeditions.org/en/m/science/news/bacteri
al-degradation-of-synthetic-plastics/
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Thank you