Studies of Mycofungicid,a Preparation Based on Trichoderma viride,for Plant Infection Control

A technology was designed for manufacturing a preparation based on Trichoderma viride Pers ex S.F. Gray that strongly suppresses the development of causative agents of certain plant diseases and displays a growth-stimulating activity. Cultivation of the strain in a liquid medium for 18–24 h produced up to 60 g dry biomass per liter nutrient medium. A marketable form created in this work conserves the activity of the mycelial preparation for six months. The preparation is compatible with insecticides (carbofos, vismetrin, talstar, and applaud) and certain fungicides (such as baitan). Tests performed with the liquid form of Mycofungicid (seeds were treated with this preparation at a dose of 20–30 g per metric ton before sowing) showed its high efficiency in protecting cereal crops from plant pathogens. The incidence of plant diseases decreased by 65%, and crop yields increased by 15–20%.     

Development and Testing of the Biosorbent Ekosorb Prepared from an Association of Oil-Oxidizing Bacteria for Cleaning Oil-Polluted Soils

A biosorbent containing an association of oil-oxidizing bacteria as the main constituent was developed, in which Lessorb, a product of moss and wood thermal processing, was used as a carrier. Xeroprotectors preserving the cell viability and oil-oxidizing activity in the biosorbent on drying and after long-term storage were selected. The use of this biosorbent for cleaning oil-polluted sod-podzol soils showed a two- to threefold cleanup rate acceleration at different pollution levels (8 and 24 l/m²), especially in the presence of a nitrogen–phosphate fertilizer. The biosorbent increased the populations of certain groups of soil microorganisms and the total soil biological activity.     

Chemicomicrobiological Diagnostics of Stress Corrosion Cracking of Trunk Pipelines

Samples of soil, subsoil, electrolyte, corrosion products, and protective coating were taken after excavating pipelines. The depth of stress corrosion cracking of the pipe steel was mostly related to counts of sulfate-reducing and denitrifying bacteria. In certain types of soil, crack depth correlated with the number of acid-producing microorganisms and aerobic chemoorganotrophs (saprophytes). A correlation was found between the extent of stress corrosion cracking of pipelines and the contents of mobile reduced iron, sulfides, organic carbon, and a number of other parameters of the surrounding soil.     

Studies of Initial Stages of Biocorrosion of Steel

Initial stages of corrosion of mild steel induced by Klebsiela rhinoscleromatis BO2 were studied in various media. The effect of the microorganism was detected 8–10 h after inoculation. The number of viable cells was virtually unchanged over one month in all media, but the corrosive activity of the strain decreased. The corrosive activity of microorganisms can be determined by spectrophotometry even after incubation for only 24 h. At a low level of organic substrate, even strong colonization with microorganisms does not inevitably result in significant damage to metals.     

Development of Biological Methods for Controlling the Aerobic Microorganism–Induced Corrosion of Carbon Steel

Cocultivation of destructor microorganisms and their antagonists decreases the corrosion loss of carbon steel by 20 to 80%. It was found that a microorganism can either accelerate or inhibit corrosion, depending on the nutrient. The magnitude of the effect on corrosion depends on the ability of the microorganism to respond to changes in the nutrient medium composition by releasing acidic or alkaline metabolites.     

Use of Biocides as Agents against Microorganism-Induced Corrosion Increases Ecological Safety

Five synergistic combinations of biocides have been identified, of which kathon plus copper sulfate is the most efficient against Serratia marcescens. Depending on the ratio of the biocides, the active concentrations needed to maintain the synergistic effect can be decreased 4- to 20-fold. Combinations of biocides with salts promoting steel passivation (such as carbonates and phosphates) have been developed, which are more potent in decreasing corrosion-induced losses of mild steel than biocides and salts taken in isolation. Biocides should be introduced into systems susceptible to biocorrosion at the start of their exploitation, otherwise higher concentrations or synergistic compositions have to be used.     

Direct Quantitative Evaluation of the Effects of Biocides on Pseudomonas fluorescens in Various Nutrient Media

A method for quantitative evaluation of the effects of biocides is presented. The method was tested in experiments with Pseudomonas fluorescens grown on various agar nutrient media. The effective concentrations of biocides that decreased the maximum specific rate of the colony biomass growth ("_m) were called S (suppressing) concentrations, and concentrations that decreased the number of colony-forming units (CFU) were taken as L (sublethal) concentrations. The efficiency of the reported approach was demonstrated in experiments with three biocides tested in four nutrient media. It was found that the biocide sensitivity of Pseudomonas fluorescens varied by a factor of 30, depending on the amount and type of the nutrient substrate.