Biotechnologia Acta

15-29

Authors: О. V. Kyrychenko

The purpose of the work was to evaluate the symbiotic productivity of soybean‒rhizobium and wheat‒azotobacter phyto-bacterial systems under the action of N-acetyl-D-glucosamine (0.01 M; 0.1 M) in vitro on the cultures of nitrogen-fixing microorganisms Bradyrhizobium japonicum 634b and Azotobacter chroococcum Т79. We have used such indicators as plants biological and seed productivity, rhizobia nodulation ability and nitrogenase activity of soybean symbioses as well as wheat rhizosphere microbiota. It was shown that the biological activity of N-acetyl-D-glucosamine during incubation with soybean nodule bacteria had a higher level of realization of the rhizobia nodulation ability: plants were more actively infected (by 12%), a greater number of nodules were formed (1.2‒2.3 times) with their greater total mass per plant (1.4‒2.1 times) and the mass of each root nodule (1.2 times), as well as the nitrogen-fixing activity of the symbiosis (1.7 times) and the functional capacity of each morpho-structural symbiotic unit (1.4 times). It provided higher (by 14‒29%) seed productivity of this system as compared with the symbiosis formed by the rhizobia monoculture. Activation of basic physiological processes in wheat such as nitrogen fixation (the activity of the rhizosphere microbiota was increased by 1.1‒1.4 times) and photosynthesis (the content of chlorophylls in leaves was increased by 1.1‒1.2 times) with N-acetyl-D-glucosamine-modified azotobacter provided a higher level of realization of the productive potential of this system in comparison with both non-infected plants (by 15%) and the variant of seed inoculation with bacteria only (by 7%). While inoculants bacteria + glucosamine had positive effect on seed productivity of the symbiotic and associative systems, it was shown no significant change in the biological productivity of soybean and wheat plants. So, the use of N-acetyl-D-glucosamine as an additional agent of carbohydrate nature in inoculants with soybean nodule bacteria and soil diazotrophs of Azotobacter genus led to a more complete realization of the symbiotic and productive potential of phyto-bacterial symbiosis and association when compared to using a diazotrophs only. Our results indicated the possibility of practical use of acetylated glucose-containing aminosaccharide in the creation of complex inoculants based on nitrogen-fixing bacteria.

38-44

Authors: D. A. Ivanchenko

The work was aimed to study the synergy of the antimicrobial activity of the prodigiosin pigment with antibiotics against bacteria of the genera Bacillus, Staphylococcus and Streptococcus. The serial dilution method was used to evaluate antimicrobial compositions, which included inhibitors of cell wall synthesis: ampicillin, benzylpenicillin, vancomycin, cefazolin, and metronidazole (nitroimidazole derivatives) in combination with the pigment prodigiosin isolated from Serratia marcescens. Each combination was tested against the studied strains. The fractional inhibitory concentration index (FICI) for each combination was calculated to determine synergy, and the results were interpreted as follows: FICI ≤0.5 ‒ synergism; FICI > 4.0 ‒ antagonism; and FICI > 0.5-4 ‒ neutralism. It was shown that the ethanol extract of prodigiosin in combination with benzylpenicillin, vancomycin, cefazolin, and metronidazole interacted differently synergistically depending on the type of microorganism. The combinations of prodigiosin and metronidazole showed a synergistic effect against Bacillus subtilis, vancomycin and cefazolin against Staphylococcus aureus and benzylpenicillin against Streptococcus pyogenes. Other combinations of prodigiosin and antibiotics showed a neutral effect, and in the case of cefazolin against Str. pyogenes, even an antagonistic effect. Thus, the study showed the synergism of prodigiosin with antibiotics depending on the type of microorganism, contributed to a several-fold decrease in the minimum inhibitory and bactericidal concentrations of each component separately, and the results indicated that prodigiosin acted separately more efficiently against gram-positive non-spore-forming bacteria. This synergistic combination of antimicrobial agents had great potency to prevent bacterial resistance.

56-63

Authors: L. Sablii, M. Korenchuk

The aim of the work is to determine the rational parameters of the malt plant wastewater treatment from ferric compounds in a flow-through experimental bioreactor with the use of duckweed. The main tasks of the study were as follows: to determine the effect of the initial concentration of the ferrum, the amount of biomass introduced and the duration of the purification process to reduce the content of ferric compounds in the wastewater. The studies were carried out on existing sewage treatment plants. They used a semi-production unit incorporated into the technology before the decontamination step. The results show that the logarithmic nature of the biological process was detected in the concentration range from 0.2 to 1.3 mg/dm3. Under these conditions, the rational values of the duration of the purification process is found to be 3-8 h with the Lemna minor biomass value not exceeding 12 g/dm3. It has been first demonstrated that the effect of sewage treatment from ferric ions in the bioreactor with Lemna minor was up to 40% and depended on the initial concentration of the ferrum compounds in water at the existing wastewater treatment plants at a semi-production unit for biological treatment of wastewater from ferric compounds.