1株四环素降解菌的分离鉴定及降解特性研究

应用微生物降解四环素具有经济有效和环境友好特点,已成为当前研究的热点。采用选择性培养基,从鸡粪中分离出1株能以四环素作为唯一碳源生长的菌株TC-1,培养7 d降解率为56.2%,初步鉴定为蜡状芽胞杆菌(Bacillus cereus)。从碳氮源组合、培养基初始pH、Na Cl浓度和装液量四方面研究了TC-1降解四环素的特性。结果表明,TC-1在以葡萄糖和酵母粉为碳、氮源生长时效果最优,培养7 d时OD600达2.17;但最优降解率出现在蔗糖和大豆蛋白胨的碳氮源组合中,为46.8%。当培养基初始pH为7时,菌株TC-1生长最好,OD600为0.44,四环素降解率为92.3%。当培养基中Na Cl浓度达15 g/L时,TC-1生长受到抑制,降解率仅为28.6%;培养基装液量为40%时降解率最高,为56.2%。     

The use of solid waste of a nylon-6 plant as a nutrient for bacterial decolourisation of dyes

Three caprolactam-degrading bacterial isolates grew in liquid synthetic medium containing solubilised solid waste of a nylon-6 production plant as the sole source of carbon and nitrogen. Typically, the caprolactam content of solid waste was decreased by 95% in 72 h by Alcaligenes faecalis. A. faecalis was the most potent caprolactam-degrading bacterium out of the three isolates. The biomass of the bacteria obtained by growth in the solubilised solid waste medium had the ability to decolourise some synthetic azo and triphenylmethane dyes. Decolourisation of dyes was obtained in static condition, in synthetic medium which contained only the components of the solid waste as the sole sources of carbon and nitrogen and also in nutritionally rich medium. The supplementation of yeast extract to solid waste medium did not increase the efficiency of decolourisation in case of two of the bacterial cultures. Depending on the dye, medium and bacteria used, decolourisation in the range of 35–94% was achieved in 48–96 h. The decolourisation was not due to the adsorption of the dyes by the bacterial biomass except in case of Procion Blue MR and Black B. Based on these observations, the simultaneous biological treatment of the solid waste of nylon-6 plant and the decolourisation of synthetic dyes present in wastewater or solid waste is envisaged.     

Production of single cell protein using waste capsicum powder produced during capsanthin extraction

Aims: To produce single cell protein (SCP) by using waste capsicum powder produced during capsanthin extraction as a substrate. Methods and results: The extraction [CPM (capsicum powder medium)] from waste capsicum powder was used as culture medium to cultivate four yeast strains. The main composition of CPM was determined. The average concentration of total sugar, total nitrogen and phosphorous of CPM were 16·3, 3·7 g l^?1 and 785·4 mg l^?1, respectively. Four yeast strains were cultured in two CPMs, and the cell mass, protein content of cells and specific growth rate of cells were determined. Addition of corn steep liquor significantly increased the cell mass production. Presence of capsaicin in CPM did not show inhibition of cell growth of yeast tested. Conclusions: CPM contained sufficient nutrients and could be used as a good medium to produce SCP. Candida utilis 1769 was chosen as the biomass producer because of its highest SCP formation (6·8 g l^?1) and higher specific growth rate (0·12 h^?1). The amino acid composition of its protein was well balanced. Significance and Impact of the Study: Utilization of waste capsicum powder can reduce environmental pollution and increase protein supply for animal feed.     

Effect of deprotonation on the conformational state of the tetracycline molecule]

Conformation rearrangements in the tetracycline molecule under the effect of the aqueous medium pH were investigated by circular dichroism and absorption spectrophotometry. Possible causes of the changes in the spectrum after the molecule deprotonation are discussed. An increase in the pH value was accompanied by folding-unfolding of the A-ring of the tetracycline molecule and its transfer within the pH neutral ranges to the conformation close to planar one and after increasing of the aqueous solution polarity to the folded conformation. The BCD chromophore did not change its initial flat conformation during deprotonation. The loss of the proton (4) by the nitrogen atom was accompanied by changes in the A chromophore chirality.     

废弃活性污泥中产聚羟基脂肪酸酯菌株Bacillus sp. PB-3的发酵条件优化

通过尼罗红染色法结合荧光显微镜镜检,从废弃活性污泥中分离得到1株高产聚羟基脂肪酸酯(PHAs)的菌株Bacillus sp.PB-3,经气相色谱法鉴定该菌株胞内产物为聚β-羟基丁酸酯(PHB)。对培养基成分及发酵条件优化后,获得最佳培养方案:12 g/L的葡萄糖为C源,2 g/L的牛肉膏为N源,初始pH 7.5,培养基装液量80 mL,转速为200 r/min,37℃培养48 h,PHB质量分数可达菌体干质量的32.09%,比优化前提高30%。     

Enzymatic hydrolysis of mycelial waste from the production of tetracycline

The process of enzymatic hydrolysis of the mycelial waste from the manufacture of tetracycline with using Streptomyces aureofaciens was studied. For the enzymatic hydrolysis, neutral and alkaline proteinases were used. It was shown that alkaline proteinase (protosubtilin G10X) provided the most efficient hydrolysis. Optimal conditions for the hydrolysis were determined: a temperature of 42 degrees C, hydrolysis time of 4 to 6 hours and enzyme concentrations of 1.25 to 2.20 mg/ml at a mycecial waste concentration of 12.5 mg/ml. The time course of changes in amino acid and amine nitrogen levels during enzymatic hydrolysis was investigated. It was demonstrated that the hydrolysis efficiency depended on the mode of enzyme addition. The highest efficiency was observed with fractional feeding of the enzyme.     

Active accumulation of tetracycline by Escherichia coli

1. At low concentrations of tetracycline (10mug/ml) net accumulation of the drug by Escherichia coli cells ceased after 7-10min. 2. At higher concentrations of tetracycline (>30mug/ml) the period of net accumulation of the drug was significantly extended. 3. The efflux of tetracycline from E. coli cells transferred from medium containing 10mug of tetracycline/ml to drug-free medium was a rapid temperature-dependent process and was accelerated by 2,4-dinitrophenol. 4. As the concentration of tetracycline in the preloading phase was increased, the rate of subsequent efflux of the drug progressively declined. The efflux of drug from cells preloaded in medium containing 200mug of tetracycline/ml was negligible, although efflux was readily provoked by 2,4-dinitrophenol, by N-ethylmaleimide or by omission of glucose from the medium. 5. The initial rate of uptake of tetracycline by E. coli cells was linearly proportional to the concentration of tetracycline in the medium up to the maximum concentration of drug obtainable under the experimental conditions used (400mug/ml, 0.83mm). 6. Although N-ethylmaleimide strongly inhibited the accumulation of tetracycline by E. coli, no evidence was obtained for the direct involvement of thiol groups in the transport process. It was concluded that N-ethylmaleimide inhibited accumulation by interruption of the energy supply of the cells. 7. Osmotic shock of E. coli cells did not significantly affect the influx of tetracycline, but promoted both efflux of tetracycline and cell lysis in cells treated with a high concentration of tetracycline. 8. A study of the distribution of tetracycline among the subcellular fractions of penicillin-induced spheroplasts preincubated with various concentrations of tetracycline indicated that 60-70% of the accumulated tetracycline was in the high-speed supernatant fraction. Sephadex chromatography showed that the tetracycline of this fraction was present as the free drug. Sephadex chromatography of a detergent extract of the membrane fraction, however, indicated that a significant proportion of the tetracycline radioactivity of this fraction was apparently bound to some macromolecular component. 9. Cellulose phosphate paper chromatography of cold-acid extracts of spheroplasts preloaded with tetracycline indicated that the accumulated drug was chemically unchanged. 10. Membrane preparations isolated from osmotically lysed penicillin-induced spheroplasts showed a temperature-dependent binding of tetracycline that was not energy-dependent and was not inhibited by N-ethylmaleimide. The binding process was stimulated by omitting Mg(2+) from the medium, but conversely was profoundly inhibited by EDTA. 11. The relevance of these findings to the probable mechanism of active tetracycline accumulation by E. coli is discussed.     

响应面模型分析高温蛋白酶菌株增殖和产酶关系

【目的】【方法】采用Box-Behnken法设计三因素三水平响应面实验,对比分析了高温蛋白酶高产菌株枯草芽孢杆菌BY25发酵过程中细菌生长与产酶之间的关系。【结果】实验表明,细菌生长与产酶的关系在各因素交互影响下变化显著。在中低水平的有机氮源添加条件下,细菌的大量繁殖显著抑制了蛋白酶产量,而在高水平的有机氮源添加条件下,细菌量的增长对产酶的作用由抑制转为促进。【结论】该结果表明,产酶诱导物有机氮源豆制品废渣的添加很可能显著提高了枯草芽孢杆菌群体中产酶菌的比率,而在没有合适诱导物的情况下通过增加细菌量并不能有效提高蛋白酶产量。     

两株四环素降解菌的分离鉴定及降解条件优化

为发掘四环素高效降解菌株,本研究从以四环素为唯一生长碳源的养鸡场粪便堆肥样品中分离筛选到2株四环素降解菌TC-04和TC-09,并通过形态特征、生理生化特征和16SrRNA基因序列分析,对其进行鉴定.采用单因素试验分别探究不同碳源、氮源、微量元素这3个培养基成分和培养时间、接种量和装液量这3个培养条件对两株菌降解四环素...     

不同规模餐馆食物浪费及其氮足迹——以北京市为例

餐饮食物浪费的普遍性和严重性已得到了社会各界的关注。通过实证研究的方法对餐饮消费中食物浪费问题进行了研究,并从食物全供应链的视角,对比分析了不同规模餐馆食物浪费的氮足迹及其环境影响。研究表明:北京市餐饮食物浪费人均浪费量为74.39g/人次,其含氮量为1.24g/人次,约占总浪费量的2%。北京市餐饮食物浪费所引起总的氮排放量为16.37 g/人次,其中有1.24g/人次的氮排放来自于食物的直接浪费,其余15.13g/人次氮排放来自于食物生产过程。北京市餐饮食物浪费的氮足迹为0.22g N/g,即每浪费1g的食物,就会有0.22 g的氮排放到环境中。对比不同规模餐馆的食物浪费情况可知,大型餐馆的人均浪费量最高,有99.38g/人次,其氮排放量也相应最大,为22.53g/人次;中型餐馆和小型餐馆的食物浪费人均量及N排放量依次减少,而快餐的最低,仅为北京市整体平均水平的1/3。     

Effect of osmotic shock on tetracycline resistance in Escherichia coli bearing an R-factor

1. Escherichia coli with an R-factor conferring resistance to tetracycline was induced to high-degree resistance by pre-exposure to the antibiotic. The degree of resistance was drastically lowered by subjecting the cells to osmotic shock. 2. Resistance to tetracycline was rapidly restored by incubating the shocked cells in a glucose-salts medium containing shock proteins prepared from tetracycline-sensitive and -resistant cells. Resistance was also restored by incubating the cells in a complex medium without shock protein. 3. The initial recovery of resistance was followed by a secondary fall in resistance when the cells were cultured in complex medium; this secondary fall was largely prevented by the addition of a low concentration (10mug/ml) of tetracycline to cells. The secondary fall was significantly less in shocked E. coli cells harbouring a mutant R-factor in which tetracycline resistance is largely constitutive. 4. Tetracycline resistance was also transiently depressed by treating R-factor-bearing cells with EDTA in tris buffer. 5. The significance of these results in relation to the mechanism of tetracycline resistance in R-factor-bearing cells is discussed.     

Retention of nutrients by the different wastes produced by the kaolin mining industry in Cornwall

Summary The chemical composition and leaching loss of applied fertilizers were measured from four waste materials derived from china clay extraction. Two waste materials, overburden and mica, had a higher nitrogen and calcium concentration, and were more efficient than sand wastes for the retention of these elements when applied as fertilizers. The possibility of using overburden and mica wastes as amendments for sand waste reclamation is briefly discussed.     

Use of an industrial grade medium and medium enhancing effects on high cell density CO fermentation by Eubacterium limosum KIST612

Studies were made on the composition of the growth medium to increase the cell concentration in a cell-recycled continuous culture (Eubacterium limosum KIST612) with carbon monoxide as a sole energy source using phosphate-buffered basal medium (PBBM) and modified PBBM. One of major limiting factors in PBBM might be nitrogen during the high cell density culture. This limitation could be overcome by increasing of inorganic nitrogen or yeast extract concentration in the medium. Anaerobic digester fluid, which could replace the organic nitrogen in PBBM, was used to develop an industrial grade medium for conversion of CO to multi-carbon compound.     

Neutral protease expression and optimized conditions for the degradation of blood cells using recombinant Pichia pastoris

Significant amount of blood waste is generated by the livestock industry. However, the poor utilizability of blood cells limited the application of blood. In our experiment, to degrade blood cells effectively, a recombinant Pichia pastoris strain with the Aspergillus oryzae neutral protease gene was generated using genetic engineering methods. The recombinant strains were screened for high protease activity on agar plates and blood cells fermentation medium using blood cells as the nitrogen source. Single-factor experiments and response surface methodology (RSM) were applied to predicted the degree of hydrolysis (DH) of blood cells and the predicted maximal DH appeared at the region where the pH, time, and temperature were 8.1, 116.6 h, and 33.9 °C, respectively. Under the proposed optimized conditions, the experimental DH value for recombinant pGAPZαA-NpI-GS115 was 49.05%. Therefore, the efficient degradation of blood cells by this recombinant stain may offer an environmental-friendly solution for the degradation of blood waste and other organic matter of similar molecular composition and more meaningfully may supply a high-quality and low-cost protein source for feed industry.     

Toxicity degradation of waste soil from a chlor-alkali factory byAzolla pinnata Lam

Cultures ofAzolla pinnata Lam., grown in various mixtures of soil plus industrial waste from a chlor-alkali factory for 30 to 60 days, resulted in the addition of significant amounts of nitrogen and organic carbon to the growing medium. A considerable decrease in the alkaline pH of the waste/soil was also recorded. On transplantation of rice seedlings into the waste/soil mixtures, after 60 days of Azolla culture it was observed that the rice survived and continued to grow in mixtures containing 30% waste whereas, in control conditions, seedlings failed to survive in above 15% waste/soil combinations.     

EFFECT OF NITROGEN SOURCE ON PLATYMONAS (CHLOROPHYTA) CELL COMPOSITION AND AMINO ACID UPTAKE RATES1

The effect of nitrogen source (nitrate, ammonia and/or amino acids) on cell composition and amino acid uptake rates was examined. Substantial levels of free amino acids accumulated intracellularly with all nitrogen sources used. Ammonia accumulated only when provided in the medium. The presence of ammonia in the medium decreased the intracellular accumulation of free amino acids, especially arginine. Amino acid uptake rates were suppressed by the presence of excess nitrogen, especially ammonia. However, the suppression of uptake did not show any particular relation to the nitrogenous cell composition.     

Changes in the composition of intracellular lipids and hydrocarbons in Candida tropicalis in the absence of growth]

The fatty acid composition of lipids and the composition of hydrocarbons were studied in Candida tropicalis cultivated on a medium with propionic acid and incubated in the conditions of starvation and on a medium containing glucose-1-6-14C but no nitrogen. Intracellular fatty acids with an odd number of carbon atoms were found to be easily metabolized by yeast cells. The content and composition of intracellular hydrocarbons were very labile and underwent intensive transformation caused by changes in the metabolism of the yeast cell.     

Organic nitrogen of tomato waste hydrolysate enhances glucose uptake and lipid accumulation in Cunninghamella echinulata

Aims: To investigate the effect of organic nitrogen on lipogenesis during growth of Cunninghamella echinulata on tomato waste hydrolysate (TWH) media. Methods and Results: Cunninghamella echinulata grown on a TWH medium rapidly took up glucose and produced large amounts of lipids. However, when some quantities of the organic nitrogen were removed from TWH (by acid followed by alkaline precipitation of proteins) the uptake of glucose was dramatically reduced and large quantities of fungal biomass having low lipid content were produced. Nevertheless, when glycerol was used as carbon source instead of glucose, the uptake rate as well as the biomass production and the lipid accumulation processes were unaffected by the TWH organic nitrogen removal. Finally, when the fungus was grown on a glucose supplemented TWH medium that contained no assimilable organic nitrogen (after further precipitation of proteins with methanol), the produced biomass contained non-negligible quantities of lipids, although glucose uptake remained low. Lipid analysis showed that the produced lipids comprised mainly of neutral lipids, which were preferentially consumed during lipid turnover. Lipid production on the original TWH medium having glucose as carbon source was 0·48 g of lipid per gram of dry biomass, corresponding to 8·7 g of lipid per litre of growth medium. The produced lipids contained 11·7%γ-linolenic acid (GLA), hence the GLA yield was more than 1 g l⁻¹. Conclusions: Organic nitrogen compounds found in TWH favour glucose (but not glycerol) uptake and lipid accumulation in C. echinulata. Significance and Impact of the Study: Agro-industrial wastes containing organic nitrogen, such as tomato waste, are produced in vast amounts causing severe environmental problems. These wastes could be used as fermentation feedstock to produce microbial lipids.     

Bacteria of the genus Acinetobacter. Methods for their isolation and primary identification

A liquid accumulation medium and a solid isolation medium for primary identification of bacteria of the genus Acinetobacter have been proposed. Both media have identical composition and contain ethanol as the only source of carbon and energy and sodium ammonium phosphate as the source of nitrogen. Besides, the modification of Baumann's medium with sodium acetate as the source of carbon and potassium nitrate as the source of nitrogen has been developed. This modified medium has simplified composition and is not inferior to the above-mentioned media in selectivity, though its use gives less satisfactory results. The two proposed media, both liquid and solid, are recommended for wide use.     

The Physiology of Encystment of Hartmannella castellanii*

SYNOPSIS. Some aspects of the physiology of encystment of the soil amoeba Hartmannella castellanii in a replacement encystment medium consisting of 5 × 10^-2 M MgCl₂ have been investigated. It is suggested that measurement of the cellulose produced during encystment in the synthesis of the cyst wall is a more reliable measure of the process than other methods tried. The degree of encystment was dependent on the physiologic state of the amoebae and the composition of the growth medium, but the initial pH of the encystment medium (C. 4.0-8.5) had little effect on the process. The requirement for Mg during encystment was probably not due to its deficiency during growth. Encystment was inhibited to varying extents by inhibitors of protein synthesis, tetracycline and chloramphenicol and also by arsenate, arsenite and iodoacetate; sodium fluoride, malonate and 2, 4-dinitrophenol were without marked effect. Addition of glucose and α-ketoglutarate to the replacement medium led to improvement in the encystment response. The presence of glutamate and histidine during encystment led to cell death. Other carbon and nitrogen sources had no effect. During encystment there was an increase in the metabolic activity of the amoebae, as measured by their oxygen consumption. This was accompanied by a decrease of about 40% in cellular dry weight and protein content. Of the other chemical components, there were marked initial increases in the levels of total carbohydrates and pentose which were followed by their depletion during cellulose synthesis. Encystment was completed after about 64 hr when the synthesis of cellulose was complete and the oxygen uptake of the amoebae fell to an immeasurable level.