Pseudomonas putida

Agrotekno Lab

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Jual Culture Pseudomonas putida

Pseudomonas putida is a rod-shaped, flagellated, gram-negative bacterium that is found in most soil and water habitats where there is oxygen. It grows optimally at 25-30 C and can be easily isolated. Pseudomonas putida has several strains including the KT2440, a strain that colonizes the plant roots in which there is a mutual relationship between the plant and bacteria. The surface of the root, rhizosphere, allows the bacteria to thrive from the root nutrients. In turn, the Pseudomonas putida induces plant growth and protects the plants from pathogens. Because Pseudomonas putida assist in promoting plant development, researchers use it in bioengineering research to develop biopesticides and to the improve plant health.

Pseudomonas putida has a very diverse aerobic metabolism that is able to degrade organic solvents such as toluene and also to convert styrene oil to biodegradable plastic Polyhydroxyalkanoates (PHA). This helps degrade the polystyrene foam which was thought to be non-biodegradable. Due to the bacteria’s strong appetite for organic pollutants, researchers are attracted to using Pseudomonas putida as the “laboratory ‘workhorse’ for research on bacteria-remediated soil processes”.  This bacteria is unique because it has the most genes involved in breaking down aromatic or aliphatic hydrocarbons which are hazardous chemicals caused by burning fuel, coal, tobacco, and other organic matter. There is great interest in sequencing the genome of Pseudomonas putida due to its strong effect in bioremediation.

Aside from aiding in bioremediation, Pseudomonas putida is very helpful in the research of different species in the genus Pseudomonas, especially Pseudomonas aeruginosa, a pathogenic bacterium that is one of the leading fatal diseases in humans. Researchers find that Pseudomonas putida, although saprophytic, can aid in the research on cystic fibrosis, an inherited disorder caused by a defective CFTR chloride transporter, which leads to recurrent opportunistic infections by Pseudomonas aeruginosa. The two bacteria are very closely related and share similar sequenced genomes (approximately 85% are shared), except Pseudomonas putida lack the genes that determine virulence. Because of its nonpathogenic nature, many researchers find Pseudomonas putida very beneficial to research due to its versatility and ease of handling.

In 1995, the scientists at The Institute for Genomic Research in Germany decoded the first complete genome sequence of Pseudomonas putida. Thirty microbial strains have been completed and fully sequenced, while another seventy-five are in the process of being sequenced. [4] Through the genome analysis, Pseudomonas putida is found to have approximately 6.2 million DNA base pairs. Among the Pseudomonas putida, the strain F1 is 5,959,964 nucleotides long and contains 61% guanine and cytosine content and 39% adenine and thymine content. While another important strain, KT2440 is 6,181,863 nucleotides long.  Pseudomonas putida has a circular genome where at least eighty genes in oxidative reductases, a family of enzymes, are involved in decomposing substances in the environment. Moreover, the majority of the genes are for detecting chemical signals in the surroundings so it can quickly respond to toxins.  This bacterium also has many important plasmids, such as the sequenced TOL and OCT plasmid, which play an important role in the degradation of pollutants.  Nonetheless, not all plasmids are helpful in bioremediation. Some create a disadvantage for Pseudomonas putida because it reduces the growth rate and is useless in function such as the plasmid R68-45.

Pseudomonas putida is a rod-shaped, nonsporeforming, gram-negative bacteria that utilizes aerobic metabolism. This bacterium also has multiple polar flagella for motility. The flagella have a waveform that is usually 2 to 3 wavelengths long. Pseudomonas putida is sensitive to the environment and suppresses the changes in the direction of flagella rotation upon sensing chemoattractants. This is very helpful in guiding the Pseudomonas putida to propel towards the seeds of the plants which provides nutrients to the bacterial cells.

Pseudomonas putida is able to tolerate environmental stresses due to its diverse control of proteins including protein and peptide secretion and trafficking, protein modification and repair, protein folding and stabilization, and degradation of proteins, peptides, and glycopeptides. [8] Some important proteins include the global regulatory proteins which link the pathway genes to the cell status. Pseudomonas putida exercises a very complex metabolism, the proteins control a particular pathway that not only depends on the signal received, but also the specific promoters and regulators in the pathway. And in turn, once the signals are received, it informs the cell of the oxygen and nutrient availability. Another important protein is the Crc protein which is part of the signal transduction pathway moderating the carbon metabolism. It also functions in biofilm production.

Pseudomonas putida has metabolism functions in biodegradable plastics. Styrene degradation in Pseudomonas putida CA-3 degrades styrene in two pathways 1) vinyl side chain oxidation and 2) attack on the aromatic nucleus of the molecule. [14] Pseudomonas putida also has sideospores, an iron chelating compound that allows the bacteria to enhance levels of iron and promote the active transport chain. Strains of Pseudomonas putida have outer membrane receptor proteins that help transport the iron complex to the sideospores, specifically known as pyoverdines, which are found in the bacterial cell. From there the iron is used in metabolic processes where oxygen is the electron acceptor.  Oxygen serves as a good electron acceptor. The oxygen byproducts, however, are toxic to the bacteria including superoxide and hydrogen peroxide. In response, Pseudomonas putida produces catalase to protect the cell from the reactive properties of the byproducts.

In addition, Pseudomonas putida has important lipids that are developed as an adaptation mechanism to respond to physical and chemical stresses. The bacteria is able to change its degree of fatty acid saturation, the cyclopropane fatty acids formation, and the cis-trans isomerization. In different phases, the cell changes its characteristics to better respond to the environment. During the transition from growth to stationary phase, there is a higher degree of saturation of fatty acid and a higher membrane fluidity which improves substrate uptake, thus regulating the cell. [9] All these characteristics allow Pseudomonas putida to survive deadly toxins in the soil and allow it to thrive in contaminated areas. Its metabolism allows these bacteria to convert harmful organic solvents to nontoxic composites which are so essential to bioremediation.

In addition to the ability for P. putida to degrade synthetic compounds, it can also use an alternative metabolic pathway such as the Entner-Doudoroff pathway. In this pathway, P. putida degrades common hexoses, such as glucose and gluconate, to yield one net ATP for every glucose molecule degraded. This is in contrast to the two net ATP produced for every glucose molecule degraded in the classic glycolysis pathway. The Entner-Doudoroff pathway begins by converting glucose to gluconate-6-phosphate through two intermediates. The first intermediate is gluconate which is then converted to 2-ketogluconate. 2-ketogluconate is then converted to gluconate-6-phosphate. It should be noted that in some cases, gluconate-6-phosphate can be produced directly via phosphorylation of gluconate. The gluconate-6-phosphate is converted to 2-Keto-3-deoxy-gluconate-6-phosphate (KDGP). Finally, KDGP is converted to triosephosphate and pyruvate. Interestingly, P. putida has many alternative pathways that it can utilize to produce energy, yet it does not use them and mainly relies on the Entner-Doudoroff pathway outlined above.