Removal of Phenol by Rhodococcus opacus 1CP after Dormancy: Insight into Enzymes' Induction, Specificity, and Cells Viability.

Biodegradation of phenol is an effective method for removing this toxicant from contaminated sites. Phenol is a toxic compound for living cells, so many bacteria degrade phenol in relatively low concentrations, up to 0.75 g L-1. The Rhodococcus opacus strain 1CP is an effective destructor of a wide range of pollutants. In the absence of a carbon source in the medium, cells of the R. opacus 1CP strain easily form cyst-like resting cells (CLC). The purpose of this work was to evaluate the viability of cells during long-term storage and the efficiency of the process of phenol destruction by R. opacus 1CP cells germinating after dormancy. Resting cells were obtained by simple cultivation in a rich medium followed by storage under static conditions. This is a simple approach to obtain a large amount of biomass. Decomposition of phenol proceeded via catechol followed by ortho-cleavage of aromatic ring. The induction of three phenol hydroxylases was detected by RT-PCR in cells germinated in a mineral medium with phenol as the carbon source. The stability of the genome of cells germinating after dormancy is shown by box-PCR. Dormant R. opacus 1CP cells, both suspended and immobilized, can be directly used for the decomposition of phenol after 4-12 months storage. In addition to phenol, after 9 months of storage, immobilized germinating cells easily metabolized 4-chlorophenol and 2,4,6-trichlorophenol. The results demonstrate a potential and simple approach toward achieving long-term storage of cells for further use in bioremediation.

Characterization of a New Pseudomonas Putida Strain Ch2, a Degrader of Toxic Anthropogenic Compounds Epsilon-Caprolactam and Glyphosate.

In this work, a new Ch2 strain was isolated from soils polluted by agrochemical production wastes. This strain has a unique ability to utilize toxic synthetic compounds such as epsilon-caprolactam (CAP) as a sole carbon and energy source and the herbicide glyphosate (GP) as a sole source of phosphorus. Analysis of the nucleotide sequence of the 16S rRNA gene of Ch2 revealed that the strain belongs to the species Pseudomonas putida. This strain grew in the mineral medium containing CAP in a concentration range of 0.5 to 5.0 g/L and utilized 6-aminohexanoic acid and adipic acid, which are the intermediate products of CAP catabolism. The ability of strain Ch2 to degrade CAP is determined by a conjugative megaplasmid that is 550 kb in size. When strain Ch2 is cultured in a mineral medium containing GP (500 mg/L), more intensive utilization of the herbicide occurs in the phase of active growth. In the phase of declining growth, there is an accumulation of aminomethylphosphonic acid, which indicates that the C-N bond is the first site cleaved during GP degradation (glyphosate oxidoreductase pathway). Culture growth in the presence of GP during the early step of its degradation is accompanied by unique substrate-dependent changes in the cytoplasm, including the formation of vesicles of cytoplasmic membrane consisting of specific electron-dense content. There is a debate about whether these membrane formations are analogous to metabolosomes, where the primary degradation of the herbicide can take place. The studied strain is notable for its ability to produce polyhydroxyalkanoates (PHAs) when grown in mineral medium containing GP. At the beginning of the stationary growth phase, it was shown that, the amount and size of PHA inclusions in the cells drastically increased; they filled almost the entire volume of cell cytoplasm. The obtained results show that the strain P. putida Ch2 can be successfully used for the PHAs' production. Moreover, the ability of P. putida Ch2 to degrade CAP and GP determines the prospects of its application for the biological cleanup of CAP production wastes and in situ bioremediation of soil polluted with GP.

Characterization of Soil Bacteria with Potential to Degrade Benzoate and Antagonistic to Fungal and Bacterial Phytopathogens.

The intensive development of agriculture leads to the depletion of land and a decrease in crop yields and in plant resistances to diseases. A large number of fertilizers and pesticides are currently used to solve these problems. Chemicals can enter the soil and penetrate into the groundwater and agricultural plants. Therefore, the primary task is to intensify agricultural production without causing additional damage to the environment. This problem can be partially solved using microorganisms with target properties. Microorganisms that combine several useful traits are especially valuable. The aim of this work was to search for new microbial strains, which are characterized by the ability to increase the bioavailability of nutrients, phytostimulation, the antifungal effect and the decomposition of some xenobiotics. A few isolated strains of the genera Bacillus and Pseudomonas were characterized by high activity against fungal phytopathogens. One of the bacterial strains identified as Priestiaaryabhattai on the basis of the 16S rRNA gene sequence was characterized by an unusual cellular morphology and development cycle, significantly different from all previously described bacteria of this genus. All isolated bacteria are capable of benzoate degradation as a sign of the ability to degrade aromatic compounds. Isolated strains were shown to be prospective agents in biotechnologies.