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A new, highly efficient xanthan-producing strain, Xanthomonas campestris M 28, was obtained. It produces up to 28 g/L of the polysaccharide on a molasses medium, which is almost two times higher than the productivity of the NRRL B-1459 strain. Whole-genome sequencing of the strain was performed with the Illumina method and nanopore sequencing. The genome of X. campestris M 28 contained one chromosome of 5 102 828 nucleotides with an average G + C content of 65.03%. The structure and physicochemical and rheological properties of the obtained xanthan were studied. It was found that the addition of xanthan to the bentonite dispersion led to the formation of primary clay particles (70 nm) and aggregates of ~190 nm without the formation of a precipitate. This indicated the interaction of macromolecules with particles and aggregates with the formation of polymer-clay bridging structures. This ensures the stability of clay dispersions and makes it possible to achieve the required rheological properties of drilling fluids based on xanthan obtained in a molasses medium, thereby reducing its cost. [ABSTRACT FROM AUTHOR]

Mutant strains of the halotolerant type-I methanotroph Methylotuvimicrobium alcaliphilum 20Z with an inactivated sps gene, which encodes sucrose phosphate synthase, and the deletion of a gene cluster for the synthesis and degradation of glycogen were obtained. Blockage of the synthesis of sucrose and glycogen increased the protein content in cells but slightly reduced the growth rate of the methanotroph grown on methane. It is shown that relatively stable methanotroph growth is possible without synthesis of the storage carbon compounds. [ABSTRACT FROM AUTHOR]

The review examines the microbiological aspects of the biological phosphorus removal from wastewater. The history of the development of biotechnology and the discovery of the physiological group of phosphate-accumulating organisms (PAOs), which biologically remove phosphorus via the phosphate uptake and storage in the form of intracellular polyphosphates, is briefly described. PAOs are characterized by a cyclic type of metabolism that occurs when the anaerobic/aerobic conditions cyclically change. Under anaerobic conditions, PAOs uptake and store organic compounds through the energy of degradation of intracellular polyphosphates. When anaerobic conditions change to aerobic or an alternative electron acceptor appears, PAOs uptake phosphates and synthesize intracellular polyphosphates using the intracellular polymeric sources of carbon and energy accumulated under anaerobic conditions. The main representatives of the PAOs, their metabolic models, and physiological characteristics are described. The basic principles of the implementation of biotechnology used in the practice of wastewater treatment for phosphorus and other nutrients are considered. [ABSTRACT FROM AUTHOR]

Mathematical modeling of the biotechnology for the removal of ammonium nitrogen from wastewater based on the anammox process was performed with the specialized BioWin software suite (EnviroSim Associates Ltd., Canada). Nitrogen removal by means of the transformation of ammonium nitrogen to molecular nitrogen was conducted in a continuous stirred bioreactor carrying both suspended and immobilized activated sludge. Both basic values of the kinetic and stoichiometric coefficients are incorporated in the BioWin software, and those that changed based on the results of the experimental studies were used for the calculations. The optimal temperature and dissolved oxygen concentration revealed by mathematical modeling were 35°C and 0.14 mg/L. The results obtained from calculations were similar to those obtained in the experiments. The calculated and experimental concentrations of ammonium, nitrites, and nitrates in the treated water were similar and comprised 10.7 and 11.7% of the initial concentration entering the bioreactor, respectively. The selected mathematical model possessed a high predictive ability for the calculation of biotechnologies based on the anammox process [ABSTRACT FROM AUTHOR]