Pilot Testing of a Microbiological Method for Disposal of Spent Hydrocarbon Oils

Pilot testing of a microbiological method for disposal of spent hydrocarbon oils (HO) by a previously developed consortium of hydrocarbon oxidizing microorganisms (HOM): Aquamicrobium lusatiense strain 854/1 (AM884147); Pseudomonas aeruginosa strain HNYM10 (JN 999888), Paracoccus aminophilus strain ATCC 7061 (NR_043242), Gordonia hydrophobica strain DSM44015 (NR_926254), Bacillus pumilus strain ATCC 7061 (NR_043242). When cultivated under flow conditions in liquid mineral medium with spent oil, their population increased from 1,5–2·104 CFU/ml to 5–6·109 CFU/ml, which was accompanied by a significant increase in their enzymatic activity. The effectiveness of biodegradation of oil at its initial concentration of 25 and 50 wt. % was 93–94 % during 60 days. All hydrocarbons in the composition of the oil to some extent underwent microbiological oxidation, and, depending on the structure, the degree of their disposal was 82–100 %.

Influence of Photochemical Reactions on the Content and Transformation of Mineral Nitrogen in Sod-Podzol Soil

The article discusses the photochemical effects of sunlight on the soil. Under the influence of light energy the amount of mineral and easy hydrolysable nitrogen, as well as labile humus substances increased in the soil. The photochemical destruction of humus substances was accompanied by an increase in their mobility and loss of colour. The article shows that the process of mineral nitrogen formation in the soil during the photochemical destruction of humus substances has two stages. The first stage includes photochemical reactions with the formation of ammonium nitrogen. The second stage is the microbiological oxidation of ammonium nitrogen to the nitrate nitrogen.

Microbiological Oxidation of High Viscosity Bitumen in Soil

This paper presents the results of an investigation of microbiological oxidation in the model soil system of high viscosity bitumen from the Bayan-Erkhet deposit (Mongolia) with a high content of heteroelements. It is shown that bitumen, being a mixture of high molecular weight components, has no inhibitory effect on the indigenous soil microflora. Its active growth in the presence of oil products starts without adaptation and lasts for a good part of experiment resulting in 15‒30 fold excess of microorganisms over its reference number. The enzymatic activity of the contaminated soil increases by a factor of 1.5‒2.0, which indicates an assimilation of various hydrocarbon compounds. The weight analysis revealed that the biodegradation of oil products after 180 days of the experiment was 50% of the initial contamination at initial waste oil concentration 50 g/kg (5%). The analysis by IR spectroscopy revealed an accumulation of oxygen-containing compounds which are intermediate products of bio-oxidation of bitumen components. The method of chromatography-mass spectrometry (GC-MS) revealed the ability of aboriginal soil microflora to mineralize virtually all hydrocarbons contained in the bitumen under study. Their biodegradation ranges from 18 to 97%. It was shown by the GC-MS method that high-molecular heteroatomic components of bitumen (resins and asphaltenes) also undergo a microbial degradation, since their molecular structure changed after the destruction. Thus, the number of structural units in a hypothetical molecule and that of heteroatoms increased due to the high content of oxygen-containing structures. In addition, the ratio of hydrocarbons (oils), resins, and asphaltenes contained in the sample is also changed.

Microbiological Oxidation of Antimony(III) with Oxygen or Nitrate by Bacteria Isolated from Contaminated Mine Sediments

ABSTRACTBacterial oxidation of arsenite [As(III)] is a well-studied and important biogeochemical pathway that directly influences the mobility and toxicity of arsenic in the environment. In contrast, little is known about microbiological oxidation of the chemically similar anion antimonite [Sb(III)]. In this study, two bacterial strains, designated IDSBO-1 and IDSBO-4, which grow on tartrate compounds and oxidize Sb(III) using either oxygen or nitrate, respectively, as a terminal electron acceptor, were isolated from contaminated mine sediments. Both isolates belonged to theComamonadaceaefamily and were 99% similar to previously described species. We identify these novel strains asHydrogenophagataeniospiralisstrain IDSBO-1 andVariovorax paradoxusstrain IDSBO-4. Both strains possess a gene with homology to theaioAgene, which encodes an As(III)-oxidase, and both oxidize As(III) aerobically, but only IDSBO-4 oxidized Sb(III) in the presence of air, while strain IDSBO-1 could achieve this via nitrate respiration. Our results suggest that expression ofaioAis not induced by Sb(III) but may be involved in Sb(III) oxidation along with an Sb(III)-specific pathway. Phylogenetic analysis of proteins encoded by theaioAgenes revealed a close sequence similarity (90%) among the two isolates and other known As(III)-oxidizing bacteria, particularlyAcidovoraxsp. strain NO1. Both isolates were capable of chemolithoautotrophic growth using As(III) as a primary electron donor, and strain IDSBO-4 exhibited incorporation of radiolabeled [14C]bicarbonate while oxidizing Sb(III) from Sb(III)-tartrate, suggesting possible Sb(III)-dependent autotrophy. Enrichment cultures produced the Sb(V) oxide mineral mopungite and lesser amounts of Sb(III)-bearing senarmontite as precipitates.

Sulfur in agriculture

Sulfur (S) deficiency in soils is becoming increasingly common in many areas of the world as a result of agronomic practices, high biomass exportation and reduced S emissions to the atmosphere. In this review, the incidence and commercial exploitation of S pools in nature are discussed, as well as the importance of S for plants and the organic and inorganic S forms in soil and their transformations, especially the process of microbiological oxidation of elemental sulfur (S0) as an alternative to the replenishment of S levels in the soil. The diversity of S0-oxidizing microorganisms in soils, in particular the genus Thiobacillus, and the biochemical mechanisms of S0 oxidation in bacteria were also addressed. Finally, the main methods to measure the S0 oxidation rate in soils and the variables that influence this process were revised.