Inorganic polyphosphates, linear polymers of orthophosphoric acid, are not only reserve phospho rus compounds of microorganisms but are also impor tant regulators involved in the switching of genetic programs and stress adaptation in bacteria [1][2][3]. Bio degradation of exogenous compounds requires signif icant restructuring of the bacterium metabolism, with a large group of genes being expressed. It has been shown that, in degrading polychlorinated biphenyl, the Pseudomonas sp. strain B4 accumulates large elec tron-dense granules mainly consisting of phosphates, according to the data of X ray microanalysis [4]. An increase in the content of polyphosphates was proven by an enzymatic method. It is believed that a parallel increase in the content of the GroEl stress protein and reactive oxygen species is evidence of the involvement of polyphosphates in the adaptation of bacteria to the consumption of polychlorinated biphenyl, which serve not only as a carbon source but also as chemical stress factors [4].P. putida KT2440 mutants deficient in polyphos phate kinase, the main enzyme synthesizing polyphos phates in bacteria, differed not only by the decreased content of polyphosphates (down to 15% of the con trol); they were also more sensitive to ultraviolet, p lac tam antibiotics, and Cd 2+ , and Cu 2+ [5]. P. putida KT2440 contained the pWWO plasmid for toluene bio degradation, which provides for the degradation of m xylene. In cultivation with this substrate, the strain mutant in the polyphosphate kinase gene had a longer lag phase as compared to the parent strain [5].These data suggest that the interrelation between the polyphosphate metabolism and biodegradation of for eign compounds by bacteria provides for cell adaptation to the assimilation of hard to reach and toxic sources of carbon. Thus, it is reasonable to reveal the features of phosphate consumption by bacteria from the media and those of the accumulation of inorganic polyphosphates during the biodegradation of such compounds.The purpose of the study is to investigate the effect of phosphate in the culture medium on the growth of P. putida BS 3701 cells and the characteristics of poly phosphate accumulation during naphthalene degra dation.
METHODSThe P. putida BS 3701 strain, which is capable of degradation of polycyclic aromatic hydrocarbons, was used in the study. The strain was obtained from the collection of the Laboratory of Plasmid Biology of the Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences (SIBPM, RAS).To cultivate the bacteria, Evans (E) mineral medium was used with a pH of 7.0-7.2 and the follow ing composition (mM): K 2 HPO 4 , 50; NH 4 C1, 5; Na 2 SO 4 , 0.1; MgCl 2 , 0.062 (μM); CaC1 2 , 1.0; and (NH 4 ) 6 Mo 7 O 24 ⋅ 4H 2 O, 0.005 [6]. The medium was Abstract-The effect of phosphate concentration in the culture medium on the growth and naphthalene deg radation by Pseudomonas putida BS 3701 was studied. The limiting concentration of phosphate was 0.4 mM and 0.1 mM under cultivation i...