Degradation of hydrogen sulfide by Xanthomonas sp. strain DY44 isolated from peat.

Xanthomonas sp. strain DY44, capable of degrading H2S, was isolated from dimethyl disulfide-acclimated peat. This bacterium removed H2S either as a single gas or in the presence of the sulfur-containing compounds methanethiol, dimethyl sulfide, and dimethyl disulfide. The maximum specific H2S removal rate, obtained in the late stationary phase, was 3.92 mmol g of dry cells-1 h-1 (6.7 x 10(-16) mol cell-1 h-1) at pH 7 and 30 degrees C through a batch experiment in a basal mineral medium. Since Xanthomonas sp. strain DY44 exhibited no autotrophic growth with H2S, the H2S removal was judged not to be a consequence of chemolithotrophic activity. By using X-ray photoelectron spectroscopy, the metabolic product of H2S oxidation was determined to be polysulfide, which has properties very similar to those of elemental sulfur. Autoclaved cells (120 degrees C, 20 min) did not show H2S degradation, but cells killed by gamma-irradiation and cell extracts both oxidized H2S, suggesting the existence of a heat-labile intracellular enzymatic system for H2S oxidation. When Xanthomonas sp. strain DY44 was inoculated into fibrous peat, this strain degraded H2S without lag time, suggesting that it will be a good candidate for maintaining high H2S removability in the treatment of exhaust gases.     

Degradation of hydrogen sulfide by Xanthomonas sp. strain DY44 isolated from peat.

Xanthomonas sp. strain DY44, capable of degrading H2S, was isolated from dimethyl disulfide-acclimated peat. This bacterium removed H2S either as a single gas or in the presence of the sulfur-containing compounds methanethiol, dimethyl sulfide, and dimethyl disulfide. The maximum specific H2S removal rate, obtained in the late stationary phase, was 3.92 mmol g of dry cells-1 h-1 (6.7 x 10(-16) mol cell-1 h-1) at pH 7 and 30 degrees C through a batch experiment in a basal mineral medium. Since Xanthomonas sp. strain DY44 exhibited no autotrophic growth with H2S, the H2S removal was judged not to be a consequence of chemolithotrophic activity. By using X-ray photoelectron spectroscopy, the metabolic product of H2S oxidation was determined to be polysulfide, which has properties very similar to those of elemental sulfur. Autoclaved cells (120 degrees C, 20 min) did not show H2S degradation, but cells killed by gamma-irradiation and cell extracts both oxidized H2S, suggesting the existence of a heat-labile intracellular enzymatic system for H2S oxidation. When Xanthomonas sp. strain DY44 was inoculated into fibrous peat, this strain degraded H2S without lag time, suggesting that it will be a good candidate for maintaining high H2S removability in the treatment of exhaust gases.     

Biochemical characterization of a fructokinase mutant of Rhizobium meliloti.

A double mutant strain (UR3) of Rhizobium meliloti L5-30 was isolated from a phosphoglucose isomerase mutant (UR1) on the basis of its resistance to fructose inhibition when grown on fructose-rich medium. UR3 lacked both phosphoglucose isomerase and fructokinase activity. A mutant strain (UR4) lacking only the fructokinase activity was derived from UR3; it grew on the same carbon sources as the parent strain, but not on fructose, mannitol, or sorbitol. A spontaneous revertant (UR5) of normal growth phenotype contained fructokinase activity. A fructose transport system was found in L5-30, UR4, and UR5 grown in arabinose-fructose minimal medium. No fructose uptake activity was detected when L5-30 and UR5 were grown on arabinose minimal medium, but this activity was present in strain UR4. Free fructose was concentrated intracellularly by UR4 > 200-fold above the external level. A partial transformation of fructose into mannitol and sorbitol was detected by enzymatic analysis of the uptake products. Polyol dehydrogenase activity was detected in UR4 grown in arabinose-fructose minimal medium. The induction pattern of polyol dehydrogenase activities in this strain might be due to slight intracellular fructose accumulation.     

Cadmium(II) Removal by a Hyperaccumulator Fungus <Emphasis Type="Italic">Phoma</Emphasis> sp. F2 Isolated from Blende Soil

A cadmium(II)-resistant fungus, strain F2, isolated from blende soil was identified as Phoma sp. by morphological study and internal transcribed spacer sequencing. This strain could accumulate 280 mg of Cd(II)/g dry weight mycelium. In liquid medium containing 163.8 mg Cd(II)/L, 96% of Cd(II) was removed by the actively growing mycelium. In addition, both oven-dried and lyophilized mycelium could effectively adsorb Cd(II). There were removed 91% and 46.2% of Cd(II) from 51.6 mg Cd(II)/L solution by lyophilized biomass and oven-dried biomass respectively. Transmission electron microscopy and energy-dispersive X-ray analysis showed the accumulation of Cd(II) in the mycelium cell walls. Our results demonstrated that Phoma sp. F2 was a hyperaccumulator for the removal of Cd(II) from contaminated soil and water.     

Isolation of a cadmium-releasing bacterium and characterization of its novel protease

Microorganisms were screened for their ability to release cadmium from scallop hepatopancreas, which is the main residue after removing of the edible parts of scallop. The isolated strain, 23-0-11, identified as Arthrobacter nicotinovorans, secreted a protease which released cadmium from scallop hepatopancreas into the liquid medium. The molecular mass of the enzyme was estimated to be 27 kDa. The sequence of the 15 N-terminal amino acids of the protease showed no close similarity with any other protein. Compared with a commercial enzyme, the purified protease had greater ability to release cadmium. The enzyme activity was greatest at 50 degrees C and pH 7.0, and was enhanced in the presence of Ca(2+), Mg(2+) and Mn(2+), while being strongly inhibited by Co(2+). The inhibition profile by the serine protease inhibitor, phenylmethylsulphonyl fluoride (PMSF), confirmed that the protease belonged to the serine protease family.     

Cadmium removal by a new strain of Pseudomonas aeruginosa in aerobic culture.

A fluorescent pseudomonad (strain CW-96-1) isolated from a deep-sea vent sample grew at 30 degrees C under aerobic conditions in an artificial seawater medium and tolerated cadmium concentrations up to 5 mM. After 140 h, strain CW-96-1 removed > 99% of the cadmium from solution. Energy dispersive microanalysis revealed that the cadmium was removed by precipitation on the cell wall; sulfide production was confirmed by growth on Kligler's agar. Based on 16S ribosomal DNA sequencing and fatty acid analysis, the microorganism is closely related to Pseudomonas aeruginosa.     

Isolation and application of Gordonia sp. JC11 for removal of boat lubricants

Boat lubricants are continuously released into the marine environment and thereby cause chronic oil pollution. This study aims to isolate lubricant-degrading microorganisms from Thai coastal areas as well as to apply a selected strain for removal of boat lubricants. Ten microorganisms in the genera of Gordonia, Microbacterium, Acinetobacter, Pseudomonas, Brucella, Enterococcus and Candida were initially isolated by crude oil enrichment culture techniques. The lubricant-removal activity of these isolates was investigated with mineral-based lubricants that had been manufactured for the 4-stroke diesel engines of fishing boats. Gordonia sp. JC11, the most effective strain was able to degrade 25-55% of 1,000 mg L(-1) total hydrocarbons in six tested lubricants, while only 0-15% of the lubricants was abiotically removed. The bacterium had many characteristics that promoted lubricant degradation such as hydrocarbon utilization ability, emulsification activity and cell surface hydrophobicity. For bioaugmentation treatment of lubricant contaminated seawater, the inoculum of Gordonia sp. JC11 was prepared by immobilizing the bacterium on polyurethane foam (PUF). PUF-immobilized Gordonia sp. JC11 was able to remove 42-56% of 100-1,000 mg L(-1) waste lubricant No. 2 within 5 days. This lubricant removal efficiency was higher than those of free cells and PUF without bacterial cells. The bioaugmentation treatment significantly increased the number of lubricant-degrading microorganisms in the fishery port seawater microcosm and resulted in rapid removal of waste lubricant No. 2.     

Heavy metal accumulation by immobilized cells of a Citrobacter sp.

Summary Immobilized cells of a strain of a Citrobacter sp. were effective in the removal of cadmium, lead and copper from single and mixed metal flows, and from synthetic effluents. About 80% of the presented metal was removed, and this was increased to nearly 100% by the incorporation of additional immobilized cell column units.     

Polyhydroxyalkanoate (PHA) production using waste vegetable oil by Pseudomonas sp. strain DR2

To produce polyhydroxyalkanoate (PHA) from inexpensive substrates by bacteria, vegetable-oil-degrading bacteria were isolated from a rice field using enrichment cultivation. The isolated Pseudomonas sp. strain DR2 showed clear orange or red spots of accumulated PHA granules when grown on phosphate and nitrogen limited medium containing vegetable oil as the sole carbon source and stained with Nile blue A. Up to 37.34% (w/w) of intracellular PHA was produced from corn oil, which consisted of three major 3-hydroxyalkanoates; octanoic (C8:0, 37.75% of the total 3-hydroxyalkanoate content of PHA), decanoic (C10:0, 36.74%), and dodecanoic (C12:0, 11.36%). Pseudomonas sp. strain DR2 accumulated up to 23.52% (w/w) of PHAMCL from waste vegetable oil. The proportion of 3- hydroxyalkanoate of the waste vegetable-oil-derived PHA [hexanoic (5.86%), octanoic (45.67%), decanoic (34.88%), tetradecanoic (8.35%), and hexadecanoic (5.24%)] showed a composition ratio different from that of the corn-oil-derived PHA. Strain DR2 used three major fatty acids in the same ratio, and linoleic acid was the major source of PHA production. Interestingly, the production of PHA in Pseudomonas sp. strain DR2 could not occur in either acetate- or butyrate-amended media. Pseudomonas sp. strain DR2 accumulated a greater amount of PHA than other well-studied strains (Chromobacterium violaceum and Ralstonia eutropha H16) when grown on vegetable oil. The data showed that Pseudomonas sp. strain DR2 was capable of producing PHA from waste vegetable oil.     

Metabolism of glyphosate in Pseudomonas sp. strain LBr

Metabolism of glyphosate (N-phosphonomethylglycine) by Pseudomonas sp. strain LBr, a bacterium isolated from a glyphosate process waste stream, was examined by a combination of solid-state 13C nuclear magnetic resonance experiments and analysis of the phosphonate composition of the growth medium. Pseudomonas sp. strain LBr was capable of eliminating 20 mM glyphosate from the growth medium, an amount approximately 20-fold greater than that reported for any other microorganism to date. The bacterium degraded high levels of glyphosate, primarily by converting it to aminomethylphosphonate, followed by release into the growth medium. Only a small amount of aminomethylphosphonate (about 0.5 to 0.7 mM), which is needed to supply phosphorus for growth, could be metabolized by the microorganism. Solid-state 13C nuclear magnetic resonance analysis of strain LBr grown on 1 mM [2-13C,15N]glyphosate showed that about 5% of the glyphosate was degraded by a separate pathway involving breakdown of glyphosate to glycine, a pathway first observed in Pseudomonas sp. strain PG2982. Thus, Pseudomonas sp. strain LBr appears to possess two distinct routes for glyphosate detoxification.     

Metabolism of glyphosate in Pseudomonas sp. strain LBr.

Metabolism of glyphosate (N-phosphonomethylglycine) by Pseudomonas sp. strain LBr, a bacterium isolated from a glyphosate process waste stream, was examined by a combination of solid-state 13C nuclear magnetic resonance experiments and analysis of the phosphonate composition of the growth medium. Pseudomonas sp. strain LBr was capable of eliminating 20 mM glyphosate from the growth medium, an amount approximately 20-fold greater than that reported for any other microorganism to date. The bacterium degraded high levels of glyphosate, primarily by converting it to aminomethylphosphonate, followed by release into the growth medium. Only a small amount of aminomethylphosphonate (about 0.5 to 0.7 mM), which is needed to supply phosphorus for growth, could be metabolized by the microorganism. Solid-state 13C nuclear magnetic resonance analysis of strain LBr grown on 1 mM [2-13C,15N]glyphosate showed that about 5% of the glyphosate was degraded by a separate pathway involving breakdown of glyphosate to glycine, a pathway first observed in Pseudomonas sp. strain PG2982. Thus, Pseudomonas sp. strain LBr appears to possess two distinct routes for glyphosate detoxification.     

红假单胞菌去除养鱼废水三态氮及COD的研究

利用红假单胞菌(Rhodopseudomonas sp.)wps对鲫鱼养殖废水三态氮及COD进行处理.菌株wps对水体亚硝氮的去除率随菌浓的降低而降低,当添加菌液量降到0.4 mL(终浓度约为5×10⁴cell·mL^-1)时,其对亚硝氮的去除效果已不明显,但同时投加400μg碳源明显提高其亚硝氮去除率,高出对照20.06%;菌株wps对氨氮也有一定去除效果,但碳源的添加对氨氮的去除影响更大;同时施加0.4 mL wps菌液和40μg碳源对硝氮和COD的去除率分别比对照提高20.51%和22.03%.光照与否对其处理养鱼废水的效果影响不大.PCR-DGGE结果分析显示,菌株wps在与土著光合细菌的竞争中处于劣势.     

阿特拉津降解菌株的分离和鉴定

从农药厂废水中分离到6株能以除草剂阿特拉津为唯一氮源生长的细菌,即假单胞菌（Pseudomonas spp,.)AD1,AD2和AD6,土壤杆菌（Agrobacterium sp.)AD4,黄单胞菌（Xanthomonas sp.)AD5,欧氏菌（Erwinia sp.)AD7,AD1菌株能使无机盐培养基中的0．3g/L阿特拉津在72h内降解99．9％,当以AD1,AD2,AD4,AD5,AD6和AD7菌株的总DNA为模板进行PCR扩增时,除AD2菌株以外,均得到了与献报道的假单胞菌ADP菌株的阿特拉津氯水解酶基因（atzA)同源的PCR产物。     

Historical and recent achievements in the field of microbial degradation of natural and synthetic rubber

This review intends to provide an overview of historical and recent achievements in studies of microbial degradation of natural and synthetic rubber. The main scientific focus is on the key enzymes latex-clearing protein (Lcp) from the Gram-positive Streptomyces sp. strain K30 and rubber oxygenase A (RoxA) from the Gram-negative Xanthomonas sp. strain 35Y, which has been hitherto the only known rubber-degrading bacterium that does not belong to the actinomycetes. We also emphasize the importance of knowledge of biodegradation in industrial and environmental biotechnology for waste natural rubber disposal.     

一株聚氨酯降解菌的分离及其降解特性解析

利用微生物对聚氨酯 (Polyurethane,PUR) 类污染物进行生物降解是目前的研究热点之一。寻找能高效降解聚氨酯的微生物是该类研究的重要前提。文中从塑料垃圾填埋场中分离培养了1株PUR高效降解菌株P10。基于菌落形态观察和16S rDNA系统发育分析,鉴定其为短芽孢杆菌属Brevibacillus的细菌。通过PUR的模式底物水性聚氨酯 (Impranil DLN) 比浊法,确定了该菌株能在6 d内降解71.4%的Impranil DLN。此外,菌株P10能够利用商业聚氨酯海绵作为唯一碳源进行生长;通过降解条件的优化,在5% (V/V) LB作为额外碳源的辅助下实现了6 d内对50 mg PUR泡沫的降解。以上结果表明Brevibacillus sp. P10在聚氨酯废弃物的生物降解过程中具有一定的应用潜力。     

Cadmium accumulation by a Citrobacter sp

Cadmium accumulation by a Citrobacter sp. growing in the presence of the metal occurred as a sharp peak during the mid-exponential phase of growth, but cultures showed considerable inhibition of growth compared to cadmium-free controls. This problem was overcome by pregrowing the cells in cadmium-free medium and subsequently exposing them to the metal in the resting state, under which conditions higher concentrations of cadmium were tolerated and metal uptake was enhanced. This ability was retained when the cells were immobilized and then challenged with a flow containing Cd2+; 65% of the metal presented was removed from solution. The influence on uptake of the composition of the exposure buffer and of various cell treatments were investigated and the results are discussed with respect to the anticipated speciation of the cadmium presented to the cells and also with respect to the probable mechanism of metal uptake. This is thought to occur through the activity of a cell-bound phosphatase, induced during pre-growth by the provision of glycerol 2-phosphate as sole phosphorus source. Continued enzyme function in resting cells would then precipitate the metal as cell-bound cadmium phosphate.     

Aerobic sulfide production and cadmium precipitation by Escherichia coli expressing the Treponema denticola cysteine desulfhydrase gene

The cysteine desulfhydrase gene of Treponema denticola was over-expressed in Escherichia coli to produce sulfide under aerobic conditions and to precipitate metal sulfide complexes on the cell wall. When grown in a defined salts medium supplemented with cadmium and cysteine, E. coli producing cysteine desulfhydrase secreted sulfide and removed nearly all of the cadmium from solution after 48 h. A control strain produced significantly less sulfide and removed significantly less cadmium. Measurement of acid-labile sulfide and energy dispersive X-ray spectroscopy indicated that cadmium was precipitated as cadmium sulfide. Without supplemental cysteine, both the E. coli producing cysteine desulfhydrase and the control E. coli demonstrated minimal cadmium removal.     

Removal of copper ion by Pseudomonas spp.

Copper-resistant Pseudomonas sp. 41Y, Pseudomonas pseudomallei 13-1 and Pseudomonas aeruginosa 7 were used in the present study. When the latter two organisms were added to copper-containing 1/3 strength Tryptic Soy Broth, more than 99.5% of the copper ion was removed from the medium within 24 h. If copper solution was added to hog waste slurry, a reduction in the copper ion concentration could be detected only when the added bacteria started to grow in it, whereas in a mineral medium supplemented with glycerol-2-phosphate, both bacteria could remove about 50% of the copper ion from the medium within 24 h. When cell suspension of Pseudomonas sp. 41Y was autoclaved, no copper ion removal was observed. Different incubation temperatures, including 30 degrees C, 37 degrees C and 45 degrees C, had no effect on the percent of copper ion removed by both Pseudomonas sp. 41Y and P. pseudomallei 13-1. On the other hand, if the pH value of the solution was lowered from 8.2 to 6.0, there was a drastic decrease in copper removal. A similar reduction of copper ion removal ability was also observed with the addition of lead ion. When cells of Pseudomonas sp. 41Y were embedded in sodium alginate, there was a decrease in its ability to remove copper ion as compared to the free-living cells.     

Microplate Technique for Determining Accumulation of Metals by Algae

A microplate technique was developed to determine the conditions under which pure cultures of algae removed heavy metals from aqueous solutions. Variables investigated included algal species and strain, culture age (11 and 44 days), metal (mercury, lead, cadmium, and zinc), pH, effects of different buffer solutions, and time of exposure. Plastic, U-bottomed microtiter plates were used in conjunction with heavy metal radionuclides to determine concentration factors for metal-alga combinations. The technique developed was rapid, statistically reliable, and economical of materials and cells. Results (expressed as concentration factors) were in reasonably good agreement with literature values. All species of algae studied removed mercury from solution. Green algae proved better at accumulating cadmium than did blue-green algae. No alga studied removed zinc, perhaps because cells were maintained in the dark during the labeling period. Chlamydomonas sp. proved superior in ability to remove lead from solution.     

An interstrain difference in cholesterol synthesis in vitro in mice, dependent upon a difference in endogenous NADPH-generating capacity

Earlier experiments have shown that significantly more endogenously generated NADPH is available for reduction of corticosterone in liver homogenates from C57BL/10 male mice than in those from the DBA/2 strain. To test the effect of this interstrain difference upon a representative NADPH-requiring biosynthetic pathway in vitro, the biosynthesis of cholesterol from mevalonic acid was studied in homogenates of livers from the two strains of mice, with and without addition of an NADPH-generating system. The incorporation of mevalonic acid into cholesterol in homogenates from the C57BL/10 strain is little affected by omission of the NADPH-generating system, but in the DBA/2 strain, addition of an NADPH-generating system is necessary to elevate the level of cholesterol synthesis to that of the C57BL/10 strain. Without this addition, the DBA/2 homogenate mainly produces lanosterol and other precursors of cholesterol which require NADPH for their further metabolism.