Enhanced removal efficiency of malodorous gases in a pilot-scale peat biofilter inoculated with Thiobacillus thioparus DW44

A newly isolated autotrophic bacterium, Thiobacillus thioparus DW44, which is capable of degrading sulfur-containing gases, was inoculated into a pilot-scale peat biofilter to treat the exhaust gas from a night soil treatment plant. Hydrogen sulfide (H₂S), methanethiol (MT), dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the exhaust gas were efficiently removed for six months. Average removal ratios were 99.8% for H₂S, 99.0% for MT, 89.5% for DMS and 98.1% for DMDS at a space velocity of 46 h⁻¹ during the period of operation. No acclimation period was needed to reach such a high efficiency in the removal of the gases, indicating that the ability of this bacterium to remove these gases was occurred immediately after its inoculation to the peat. Ammonia (NH₃) in the exhaust gas was neutralized with SO₄²⁻, which is the final product of the oxidation of H₂S, MT, DMS and DMDS by the bacterium. No remarkable decline of pH, which often causes a deterioration in bacterial activity, was observed, mainly because of the reaction of SO₄²⁻ with NH₃. This study is the first report on the application of an isolated microorganism to a practical deodorizing system. The inoculation of T. thioparus DW44 into the pilot-scale peat biofilter could overcome such disadvantages of the conventional peat biofilter as a long acclimation period to reach a constant gas removability and the low removability of DMS, and resulted in enhanced removal efficiency of malodorous gases.     

Enzymes of Intermediary Carbohydrate Metabolism in the Obligate Autotrophs Thiobacillus thioparus and Thiobacillus neapolitanus

Levels of enzymes operative in the Embden-Meyerhof-Parnas (glycolytic) pathway, pentose phosphate cycle, citric acid cycle, and certain other phases of intermediary carbohydrate metabolism have been compared in Thiobacillus thioparus and T. neapolitanus. All enzymes of the glycolytic pathway except phosphofructokinase were demonstrated in both organisms. There were some striking quantitative differences between the two organisms with respect to the activities of the individual enzymes of the glycolytic pathway and the citric acid cycle. Qualitative differences were also found: the isocitrate dehydrogenase activity of T. thioparus is strictly nicotinamide adenine dinucleotide phosphate (NADP)-dependent, whereas that of T. neapolitanus is primarily nicotinamide adenine dinucleotide-dependent, activity with NADP being low; the glucose-6-phosphate dehydrogenase of T. thioparus is particulate, whereas that of T. neapolitanus is partly soluble and partly particulate; the 6-phosphogluconate dehydrogenase of T. thioparus is soluble, that of T. neapolitanus is partly soluble and partly particulate. All enzymes which function in the carbon reduction cycle were present at very high levels. In contrast, enzymes which operate exclusively in cycles other than the carbon reduction cycle were present at low levels. Of the enzymes not operative in the carbon reduction cycle that were examined, isocitric dehydrogenase had the highest specific activity. Both organisms possessed reduced nicotinamide adenine dinucleotide dehydrogenase activity. The qualitative and quantitative aspects of the data are discussed in relation to possible biochemical explanations of obligate autotrophy.     

Active transport of amino acids in Thiobacillus thioparus is a low-affinity process.

A method for the isolation of amino acid auxotrophs of Thiobacillus thioparus is described. Characterization of a leucine auxotroph indicated that leucine biosynthesis in T. thioparus was not different from that of heterotrophic bacteria. T. thioparus cells accumulated amino acids via an active mechanism. Kt values of amino acid transport were between 15 and 330 microM, and Vmax values were 200 to 350 pmol min-1 mg of protein-1. Amino acid transport was carried out by a limited number of systems, each responsible for the uptake of several amino acids. Amino acid auxotrophs of T. thioparus exhibited transport and growth properties similar to those of transport-deficient mutants of heterotrophs which lost the high-affinity, but retained the low-affinity, amino acid transport systems.     

Performance and macrokinetic analysis of biofiltration of toluene and p-xylene mixtures in a conventional biofilter packed with inert material

Interactions of toluene and p-xylene in air treatment biofilters packed with an inert filter media were studied. The effect of the inlet load of toluene, p-xylene and mixtures of both compounds on the biodegradation rate was analyzed in three lab-scale biofilters. A maximum elimination capacity (EC) of 26.5 and 40.3 g C m⁻³ h⁻¹ for an inlet load (IL) of 65.6 and 57.8 g C m⁻³ h⁻¹ was obtained for p-xylene and toluene biofilters, respectively. Inhibition of p-xylene biodegradation by the presence of toluene took place when the mixture was treated, whereas the presence of p-xylene had an enhancing effect on the toluene removal efficiency. Specific growth rates (μ) from 0.019 to 0.068 h⁻¹ were calculated in the mixed biofilter, where the highest values were similar to mixtures with lower p-xylene levels (IL_p-Xyl 8.84 ± 0.29 g C m⁻³ h⁻¹). Michaelis-Menten and Haldane type models were fitted to experimental EC for p-xylene and toluene biofilters, respectively.     

Design of a biofilter packed with crab shell and operation of the biofilter fed with leaf mold solution as a nutrient

After measuring toluene adsorption (15.7 mg-toluene/g-material), water holding capacity (18.5%), organic content (53.8%), specific surface area (18.1 m²/g-material), and microbial attachment, crab shells were chosen as the main packing material for a biofilter design. The crab shells, cheap and abundant in the Gangneung area, also have relatively rigid structure, low density, and ability to neutralize acids generated during mineralization of toluene. Since towel scraps have water holding capacity as high as 301.2%, 10% of the total packing was supplemented with them to compensate for low water holding capacity of the crab shells. The biofilter fed with defined chemical medium under 0.8∼1.3 mg/L of inlet toluene concentration and 18 seconds of residence time showed satisfactory removal efficiency of over 97% and 72.8 g/h·m³ of removal capacity. For the purpose of deceasing operation costs, leaf mold solution was tried as an alternative nutrient instead of a defined chemical medium. The removal efficiency and removal capacity were 85% and 56.3 g/h·m³, respectively, using the same inlet toluene concentration and residence time. This research shows the possibility of recycling crab shell waste as packing material for biofilter. In addition, leaf mold was able to serve as an alternative nutrient, which remarkably decreased the operating cost of the biofilter.     

Emission of carbonyl sulfide by Thiobacillus thioparus grown with thiocyanate in pure and mixed cultures

Abstract The biological activity of the heat-stable enterotoxin of Vibrio cholerae non-O1 (NAG-ST) was found to be predominantly associated with the periplasmic extract (about four-fold higher than the culture supernatant) of a recombinant E. coli (JM109) strain carrying the NAG-St toxin gene. Four molecular species of NAG-ST, two each from the periplasmic extract and culture supernatant of JM109, were purified. Amino acid sequence analysis of the four NAG-ST peptides isolated by HPLC revealed that they all differed from that of the mature 17-amino acid residue NAG-ST released by V. cholerae non-O1. The M _r-values of the peptides obtained from the periplasmic extract were 4331 and 2785, while those recovered from the culture supernatant were 3154 and 2785. It thus appears that V. cholerae NAG-ST is synthesized as larger molecules in the recombinant E. coli strain. The differences in sizes of the exported NAG-ST molecule could relate to difference in the enzyme cleavage system between E. coli and V. cholerea .     

Leakage of cellular material from Thiobacillus ferrooxidans in the presence of organic acids.

Thiobacillus ferroodixans cells released varying amounts of iron, phosphate, sugar, ribonucleic acid, deoxyribonucleic acid, and substances that absorbed light at both 260 and 280 nm, when exposed to 10(-2) to 10(-1) M concentrations of these organic acids: propionic, butyric, valeric, hexanoic, and oxalacetic. These acids also retarded iron oxidation by the cells. Electron microscope observation of cells after exposure to the organic acids showed varying degrees of cell envelope disruption, suggesting that the mode of inhibition of autotrophic iron oxidation in the cell involves interference with the function of the cell envelope, possibly the cell membrane.     

Optimization of nutrient supply in a downflow gas-phase biofilter packed with an inert carrier

Several methodologies were tested to supply nutrients to a downflow biofilter packed with perlite and used to treat toluene-polluted air. Despite the presence of an inorganic carrier, elimination capacities of up to around 60 g/m³ per hour could be maintained when a basal medium, containing nitrogen, phosphorus and potassium, was supplied once every fortnight or even once a month rather than once a week. Experimental results also indicated that the addition of vitamins or trace minerals to the basal aqueous medium hardly improved biofilter performance. Furthermore, the nutrient supply could be combined with a biomass control strategy, using air sparging, without any adverse effect on biofilter performance compared to supplying nutrients alone, and limiting the accumulation of excess biomass on the packing material. The performance of the biofilter was not significantly affected by temperature fluctuations between 25 and 33 °C. Electronic Publication     

Characterization of Thiobacillus thioparus LV43 and its distribution in a chemoautotrophically based groundwater ecosystem.

Bacterial strain LV43 was previously isolated from a floating microbial mat located in Movile Cave, the access point to a chemoautotrophically based groundwater ecosystem in southern Romania. This gram-negative, rod-shaped organism grows autotrophically through the oxidation of thiosulfate and sulfide, but it does not grow heterotrophically. Strain LV43 grows over a pH range of 5.0 to 9.0, with an optimum near 7.5 at 28 degrees C. The pH of the medium decreased from 7.5 to 6.5 during growth on thiosulfate. Carbon isotope fractionation values for strain LV43 were within the previously reported range of fractionation values for the overall floating microbial mat in Movile Cave and were similar to values reported for chemoautotrophic sulfur-oxidizing strains of Thiobacillus neapolitanus and Thiomicrospira sp. The 16S rRNA gene sequence of strain LV43 was determined, and phylogenetic analysis indicated that strain LV43 was most closely related to Thiobacillus thioparus and the uncultured bacterial strain Strip2, which is represented by a 16S rRNA clone obtained by direct PCR from the Stripa research mine in Sweden. This identification of strain LV43 is supported by its G+C content of 62%, which is within the range reported for strains of T. thioparus. Fluorescently labeled polyclonal antibodies specific for strain LV43 were used to locate and enumerate this strain at different locations in Movile Cave and in nearby surface-water and groundwater sources. Strain LV43 was found only at aerobic, neutral-pH sites within the cave. Strain LV43 was also found outside Movile Cave in surface waters and in groundwater believed to intercept the same sulfurous aquifer as Movile Cave.     

Ammonia emissions and biodegradation of organic carbon during sewage sludge composting with different extra carbon sources

Ammonia emissions during composting result in the reduced value of agronomic production and can also pollute the air. To evaluate the influence of various carbon sources on ammonia emissions, six composting experiments were carried out with different amendments of carbon sources (glucose, sucrose and straw powder). The cumulative ammonia volatilizations were reduced from 3.11 g/kg (R6) to 2.46 g/kg (R1), 2.17 g/kg (R2), 2.23 g/kg (R4) and 1.93 g/kg (R5). Compared to the control, no significant difference of ammonia emissions and carbon degradation was observed for the mixture of R3 (3.15 g/kg), which was amended with straw powder alone. The co-addition of sucrose and straw powder led to the lowest ammonia emissions. According to these results, a higher C/N ratio did not necessarily indicate an effective solution for reducing ammonia emissions, and not all readily available carbon compounds were helpful in reducing ammonia emissions. The addition of sucrose promoted the decomposition of organic carbon during the intensive stage of ammonia emissions, and the combination of straw and sucrose prolonged this promotion. Thus, the co-addition of sucrose and straw powder made it possible to reduce ammonia emissions drastically by nitrogen immobilization.     

Effect of biomass adaptation to biodegradation of dissolved organic carbon in water

In the present study the time of adaptation of fixed biomass for biodegradation of natural organic matter was investigated. The experiments were done in columns that are usually used for rapid determination of biodegradable dissolved organic carbon (BDOC). The biomass was adapted to samples with different concentrations of organic substances before measurements by pumping water to be investigated through the columns for several days. The time of adaptation was dependent on the initial concentration of the organic matter in the water sample. The adaptation time increased from 6 to 24 h with increase of concentration of acetate solution from 2 to 10 mg/l, thus adaptation rate decreased simultaneously from 0.28 to 0.11 min⁻¹. In natural water samples with the initial concentration in the range from 4.61–10.82 mg/l of dissolved organic carbon (DOC) the maximal adaptation time was less than 24 h. During the adaptation period the increase in reproducibility and decrease in the standard deviation was observed. The study showed that adaptation of column to the different concentration of organic matter in water sample is necessary in order to decrease the bias in BDOC measurements when using columns tests.     

不同肥力棕壤溶解性有机碳、氮生物降解特性

溶解性有机碳、氮在土壤全碳、全氮含量中所占的比例很小,但却是土壤有机质中最为重要和活跃的部分。研究利用土壤溶解性有机碳、氮生物降解的测定方法,分别选取沈阳农业大学试验站不同肥力及与定位试验地紧密相连的自然林地棕壤为研究对象,开展棕壤溶解性有机碳、氮的生物降解特性的研究,为了解溶解性有机碳、氮在土壤生态系统碳、氮循环中的作用,探讨棕壤溶解性有机碳、氮与土壤肥力的关系提供理论依据。研究结果表明,棕壤林地溶解性有机碳、氮的含量最高,高肥处理次之,低肥处理含量最低。棕壤溶解性有机碳、氮与全碳、全氮和微生物量碳、氮的相关性达到极显著水平,与土壤肥力紧密相关,可以作为指示土壤肥力的重要指标。不同肥力棕壤溶解性有机碳、氮的降解速率在培养初期较快,而后逐渐减慢,降解数据符合双指数衰变模型。棕壤溶解性有机碳分别由降解速率不同的两个库组成：周转时间在1d的易分解部分和周转时间大约为400d的难分解部分。棕壤溶解性有机氮是由周转速率大约为2d的易降解部分和周转速率在99～105d左右的难分解部分组成． 经过42d的培养,浸提液中剩余溶解性有机质碳氮比值较培养前有所增加。     

Role of intermolecular disulfide bonds of the organic solvent-stable PST-01 protease in its organic solvent stability

The PST-01 protease is secreted by the organic solvent-tolerant microorganism Pseudomonas aeruginosa PST-01 and is stable in the presence of various organic solvents. Therefore, the PST-01 strain and the PST-01 protease are very useful for fermentation and reactions in the presence of organic solvents, respectively. The organic solvent-stable PST-01 protease has two disulfide bonds (between Cys-30 and Cys-58 and between Cys-270 and Cys-297) in its molecule. Mutant PST-01 proteases in which one or both of the disulfide bonds were deleted were constructed by site-directed mutagenesis, and the effect of the disulfide bonds on the activity and the various stabilities was investigated. The disulfide bond between Cys-270 and Cys-297 in the PST-01 protease was found to be essential for its activity. The disulfide bond between Cys-30 and Cys-58 played an important role in the organic solvent stability of the PST-01 protease.     

Assessing the influence of the carbon oxidation-reduction state on organic pollutant biodegradation in algal-bacterial photobioreactors

The influence of the carbon oxidation–reduction state (CORS) of organic pollutants on their biodegradation in enclosed algal–bacterial photobioreactors was evaluated using a consortium of enriched wild-type methanotrophic bacteria and microalgae. Methane, methanol and glucose (with CORS −4, −2 and 0, respectively) were chosen as model organic pollutants. In the absence of external oxygen supply, microalgal photosynthesis was not capable of supporting a significant methane and methanol biodegradation due to their high oxygen demands per carbon unit, while glucose was fully oxidized by photosynthetic oxygenation. When bicarbonate was added, removal efficiencies of 37 ± 4% (20 days), 65 ± 4% (11 days) and 100% (2 days) were recorded for CH_4, CH₃OH and C₆H₁₂O₆, respectively due to the additional oxygen generated from photosynthetic bicarbonate assimilation. The use of NO₃⁻ instead of NH₄⁺ as nitrogen source (N oxidation–reduction state of +5 vs. −3) resulted in an increase in CH₄ degradation from 0 to 33 ± 3% in the absence of bicarbonate and from 37 ± 4% to 100% in the presence of bicarbonate, likely due to a decrease in the stoichiometric oxygen requirements and the higher photosynthetic oxygen production. Hypothetically, the CORS of the substrates might affect the CORS of the microalgal biomass composition (higher lipid content). However, the total lipid content of the algal–bacterial biomass was 19 ± 7% in the absence and 16 ± 2% in the presence of bicarbonate.     

Effects of dissolved organic carbon and second substrates on the biodegradation of organic compounds at low concentrations

Pseudomonas acidovorans and Pseudomonas sp. strain ANL but not Salmonella typhimurium grew in an inorganic salts solution. The growth of P. acidovorans in this solution was not enhanced by the addition of 2.0 micrograms of phenol per liter, but the phenol was mineralized. Mineralization of 2.0 micrograms of phenol per liter by P. acidovorans was delayed 16 h by 70 micrograms of acetate per liter, and the delay was lengthened by increasing acetate concentrations, whereas phenol and acetate were utilized simultaneously at concentrations of 2.0 and 13 micrograms/liter, respectively. Growth of Pseudomonas sp. in the inorganic salts solution was not affected by the addition of 3.0 micrograms each of glucose and aniline per liter, nor was mineralization of the two compounds detected during the initial period of growth. However, mineralization of both substrates by this organism occurred simultaneously during the latter phases of growth and after growth had ended at the expense of the uncharacterized dissolved organic compounds in the salts solution. In contrast, when Pseudomonas sp. was grown in the salts solution supplemented with 300 micrograms each of glucose and aniline, the sugar was mineralized first, and aniline was mineralized only after much of the glucose carbon was converted to CO2. S. typhimurium failed to multiply in the salts solution with 1.0 micrograms of glucose per liter. It grew slightly but mineralized little of the sugar at 5.0 micrograms/liter, but its population density rose at 10 micrograms of glucose per liter or higher. The hexose could be mineralized at 0.5 micrograms/liter, however, if the solution contained 5.0 mg of arabinose per liter.(ABSTRACT TRUNCATED AT 250 WORDS)