不产生胞外多糖的假单胞菌突起菌株E16

在适宜培养条件下,Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ ３１２６０能将木糖转化为酸性胞外多糖（ＥＰＳ）,用甲基磺酸乙酯（ＥＭＳ）诱变处理Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ ３１２６０得到一株完全不产生胞外多糖的突变菌株Ｅ１６。     

不产生胞外多糖的假单胞菌突变菌株E16

在适宜培养条件下,Ｐｓｅｕｄｏｍｏｎａｓｓｐ３１２６０能将木糖转化为酸性胞外多糖（ＥＰＳ）,用甲基磺酸乙醋（ＥＭＳ）诱变处理　Ｐｓｅｕｄｏｍｏｎａｓｓｐ３１２６０得到一株完全不产生胞外多糖的突变菌株Ｅ_１６。     

假单胞菌胞外多糖发酵条件的研究

研究了假单胞菌（Ｐｓｅｕｄｏｍｏｎａｓｓｐ．６）利用木糖产胞外多糖的发酵条件。实验表明ＫＨ２ＰＯ４,Ｏ２和高碳氮比对多糖合成有促进作用,在发酵后期补加木糖有助于多糖产量的提高     

嗜盐隐杆藻胞外多糖的分离、纯化及理化特性

嗜盐隐杆藻（Ａｐｈａｎｏｔｈｅｃｅ ｈａｔｏｐｈｙｔｉｃａ）培养液经离心,浓缩、透析、有机溶剂沉淀得胞外多糖（Ｅｘｏｐｏｌｙｓａｃｃｈａｒｉｄｅｓ,ＥＰＳ）粗品,经ＤＥＡＥ－纤维素二次柱层析纯化得ＥＰＳ精品。葡聚糖Ｇ－２００凝胶过滤表明其为单一组份。对其进行理化测试并对各组分进行定量分析,多糖、已糖醛酸、硫酸根含量分别为４０．９６％２３．２７％和３４．４６％,元素分析你测得Ｃ、Ｈ、Ｎ、Ｓ含量分别为     

紫云英根瘤菌107菌株酸性胞外多糖的分离纯化及结构分析

用化学沉淀法和柱层析法,分离纯化了紫云英根瘤菌野生型１０７菌株,胞外多糖合成缺陷型变种ＮＡ０２及其回复子ＮＡ０２（Ｒ‘－１１）产生的酸性胞外多糖（ＥＰＳ）。结构组成分析表明：菌株１０７与ＮＡ０２（Ｒ’－１１）产生的ＥＰＳ糖组分均由葡萄糖、半乳糖、核糖和葡萄糖醛酸构成,而变种ＮＡ０２产生的ＥＰＳ只含葡萄糖、半乳糖和葡萄糖醛酸,与野生型显著不同。３个菌株的ＥＰＳ均有乙酰基取代,而无其它形式的取代基。Ｅ     

紫云英根瘤菌菌株107exo基因簇的遗传互补分析

紫云英根瘤菌菌株１０７经Ｔｎ５插入诱变,得到１２株胞外多糖缺陷型变种,以质粒ｐＭＮ２为载体,从其中７株ＥＰＳ＾－变种内分别构建了７个Ｒ－ｐｒｉｍｅ质粒（ｅｘｏＲ）大部分变种的ＥＰＳ＾－表型可被ｅｘｏＰ互补,恢复野生型表型（ＥＰＳ＾＋）。互补表明,１２株ＥＰＳ＾－变种可分为６个不同的互补群,其中５个在遗传上连锁,ｅｘｏＰ酶切分析,除ｅｘｏＲ－０２,ｅｘｏＲ－０４外,其余５只的外源片段均整合于ｐＭＮ２     

水稻内生联合固氮细菌的筛选,鉴定及其分布特性

利用乙炔还原法和固定１５Ｎ２ 活性测定法对分离自水稻（ Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）“越富”种子、根、茎和叶的内生细菌进行了筛选,获得２９ 株具有体外固氮能力的水稻内生联合固氮细菌。鉴定结果表明它们分属于根癌土壤杆菌（ Ａｇｒｏｂａｃｔｅｒｉｕｍ ｔｕｍｅｆａｃｉｅｎｓ （Ｓｍｉｔｈ ｅｔ Ｔｏｗｎｓｅｎｄ） Ｃｏｎｎ） ,放射土壤杆菌（ Ａ． ｒａｄｉｏｂａｃｔｅｒ （Ｂｅｉｊｅｒｉｎｃｋ ｅｔ ｖａｎ Ｄｅｌｄｅｎ） Ｃｏｎｎ） ;阴沟肠杆菌（ Ｅｎｔｅｒｏｂａｃｔｅｒ ｃｌｏａｃａｅ （Ｊｏｒｄａｎ） Ｈｏｒｍａｅｃｈｅ ｅｔ Ｅｄｗａｒｄｓ） ,成团肠杆菌（ Ｅ． ａｇｇｌｏｍｅｒａｎｓ （Ｂｅｉｊｅｒｉｎｃｋ） Ｅｗｉｎｇ ｅｔ Ｆｉｆｅ） ,坂崎肠杆菌（ Ｅ． ｓａｋａｚａｋｉｉ Ｆａｍｅｒ ｅｔ ａｌ．） ;皮氏产碱菌（ Ａｌｃａｌｉｇｅｎｅｓ ｐｉｅｃｈａｕｄｉｉ Ｋｉｒｅｄｊｉａｎ ｅｔ ａｌ．） ,反硝化产碱菌（ Ａ． ｄｅｎｉｔｒｉｆｉｃａｎｓ （Ｌｅｉｆｓｏｎ ｅｔ Ｈｕｇｈ） Ｒｕｇｅｒ ｅｔ Ｔａｎ） ;类产碱假单胞菌（ Ｐｓｅｕｄｏｍｏｎａｓ ｐｓｅｕｄｏａｌｃａｌｉｇｅｎｅｓ Ｓｔａｎｉｅｒ） ,产碱假单胞菌（ Ｐ． ａｌｃａｌ     

从感染TMV的番茄叶纯化胞外β-N-乙酰氨基己糖苷酶

番茄系统感染ＴＭＶ（ｔｏｂａｃｃｏ ｍ ｏｓａｉｃｖｉｒｕｓ）诱导叶β－Ｎ－乙酰氨基己糖苷酶活性升高。番茄叶胞外提取液经冰冻干燥浓缩、－ ２０℃丙酮沉淀、ＣＭ－Ｓｅｐｈａｄｅｘ Ｃ－２５ 离子交换层析,ＰＢＥ ９４（Ｐｏｌｙｂｕｆｆｅｒ Ｅｘｃｈａｎｇｅｒ ９４, Ｓｉｇｍ ａ）聚焦层析和Ｓｅｐｈａｄｅｘ Ｇ－１５０ 凝胶层析纯化,获得纯化的β－Ｎ－乙酰氨基己糖苷酶。凝胶层析测得该酶的分子量为１４５ ｋＤ,ＳＤＳ－ＰＡＧＥ测得该酶的分子量为７５ ｋＤ,证明该酶由两个亚基构成。该酶能水解ｐ－硝基苯基－Ｎ－乙酰－β－Ｄ－氨基葡萄糖苷（ｐＮＰ－β－Ｄ－ＧｌｃＮＡｃ）和Ｐ－硝基苯基－Ｎ－乙酰－β－Ｄ－氨基半乳糖苷（ｐＮＰ－β－Ｄ－ＧａｌＮＡｃ）两种底物,能被过碘酸氧化,Ｓｃｈｉｆｆ试剂染色。在感染ＴＭＶ 的番茄叶片中,β－Ｎ－乙酰氨基己糖苷酶活性大部分位于胞外     

信号肽疏水性的提高促进青霉素G酰化酶分泌

设计和合成了一段具有连续１０仆亮氨酸强疏水核心的信号肽（ａｒｔｉｆｉｃｉａｌ ｓｉｇｎａｌ ｐｅｐｔｉｄｅ,ＡＳＰ）,由ＥｃｏＲＩ－ＫｐｎＩ位点融合到青霉素Ｇ酰化酶（ｐｅｎｉｃｉｌｌｉｎ Ｇａｃｙｌａｓｅ,ＰＡＣ）信号肽（ｗｉｌｄ ｔｙｐｅｓｉｇｎａｌ ｐｅｐｔｉｄｅ,ＷＴＳＰ）的－４Ｐｒｏ位点,分别构建了ＰＡＣ表达质粒：ｐＫＫｐａｃ△ＳＰ,ｐＫＫｐａｃＷＴＳＰ,ｐＫＫｐａｃＡＳＰ,ｐＥＴｐａｃ     

紫云英根瘤菌菌株107exo基因簇的遗传互补分析

紫云英根瘤菌菌株１０７经Ｔｎ５插入诱变,得到１２株胞外多糖缺陷型变种,以质粒ｐＭＮ２为载体,从其中７株ＥＰＳ－变种内分别构建了７个Ｒ－Ｐｒｉｍｅ质粒（ｅｘｏＲ＇）,大部分变种的ＥＰＳ－表型可被ｅｘｏＲ＇互补,恢复野生型表型（ＥＰＳ＋）。互补表明,１２株ＥＰＳ－变种可分为６个不同的互补群,其中５个在遗传上连锁。ｅｘｏＲ＇酶切分析,除ｅｘｏＲ＇－０２,ｅｘｏＲ＇－０４外,其余５只的外源片段均整合于ＰＭＮ２的两同向重复序列ＩＳ２１之间。     

IR study of self-assembly of capsular exopolymers from Pseudomonas sp. NCIMB 2021 on hydrophilic and hydrophobic surfaces

Capsular exopolymers (EPS) of the bacterium Pseudomonas sp. NCIMB 2021 are allowed to self-assemble on hydrophilic and hydrophobic gold surfaces. Tapping mode atomic force microscopy confirms the differences in the surface topography between EPS adsorbed on both surfaces. Fourier-transform IR spectroscopy indicates that the EPS surface coverage is much greater on the hydrophobic surface. Furthermore, an increased contribution is observed from hydrophobic (i.e., methyl and tyrosyl residues) and electrostatic (i.e., carboxylate residues) groups at the hydrophobic surface, but there is relatively less neutral polymer compared to the hydrophilic surface. The behavior of this EPS is in agreement with the behavior of cells of Pseudomonas sp. NCIMB 2021 at hydrophilic and hydrophobic surfaces.     

Extracellular polysaccharides produced by cooling water tower biofilm bacteria and their possible degradation

The extracellular polymers (EPS) of biofilm bacteria that can cause heat and mass transfer problems in cooling water towers in the petrochemical industry were investigated. In addition, these microorganisms were screened for their ability to grow and degrade their own EPS and the EPS of other species. Twelve bacteria producing the most EPS were isolated from cooling water towers and characterized biochemically by classic and commercial systems. These were species of Pseudomonas, Burkholderia, Aeromonas, Pasteurella, Pantoea, Alcaligenes and Sphingomonas. EPS of these species were obtained by propan-2-ol precipitation and centrifugation from bacterial cultures in media enriched with glucose, sucrose or galactose. EPS yields were of 1.68-4.95 g l(-1). These EPS materials were characterized for total sugar and protein contents. Their total sugar content ranged from 24 to 56% (g sugar g(-1) EPS), and their total protein content ranged from 10 to 28% (g protein g(-1) EPS). The monosaccharide compositions of EPS were determined by HPLC. Generally, these compositions were enriched in galactose and glucose, with lesser amounts of mannose, rhamnose, fructose and arabinose. All bacteria were investigated in terms of EPS degradation. Eight of the bacteria were able to utilize EPS from Burkholderia cepacia, seven of the bacteria were able to utilize EPS from Pseudomonas sp. and Sphingomonas paucimobilis. The greatest viscosity reduction of B. cepacia was obtained with Pseudomonas sp. The results show that the bacteria in this study are able to degrade EPS from biofilms in cooling towers.     

Role of beta 1-4 linked polymers in the biofilm structure of marine Pseudomonas sp. CE-2 on 304 stainless steel coupons

Pseudomonas sp CE-2 cells attach and form biofilms on 304-stainless steel (SS) coupons. A series of experiments were carried out in order to understand the role of exopolysaccharides (EPS) in the formation and maintenance of CE-2 biofilms on SS coupons. The biofilm density and EPS concentration increased over the period of incubation and the highest values for both were recorded after 72 h. Calcofluor and the lectin concanavalin A (Con A) showed a positive interaction with 72-h old biofilms, indicating the presence of beta 1-4 linked polymers, and alpha-d-glucose and alpha-d-mannose in the biofilm matrix of CE-2. When the CE-2 cells were grown in the presence of calcofluor (200 microg ml(-1)), biofilm formation was significantly reduced (approximately 85%). Conversely, the lectins Con A or WGA did not influence the CE-2 biofilms on the SS coupons. Furthermore, treatment with cellulase, an enzyme specific for the degradation of beta 1-4 linked polymers, removed substantial amounts of CE-2 biofilm from SS coupons. These results strongly suggest the involvement of beta 1-4 linked polymers in the formation and maintenance of Pseudomonas sp. CE-2 biofilms on SS coupons.     

Isolation and biochemical characterization of extracellular polymeric secretions (EPS) from modern soft marine stromatolites (Bahamas) and its inhibitory effect on CaCO3 precipitation

Bahamian soft marine stromatolites consist of cyanobacterial biofilms and carbonate sand grains (ooids) embedded in their extracellular polymeric secretions (EPS). EPS were isolated from natural marine stromatolites and the laboratory cultured stromatolite forming cyanobacterium isolate Schizothix sp. Laboratory investigations were conducted to examine biochemical characteristics and the role of EPS in the inhibition of CaCO3 precipitation. EPS consisted of acid polysaccharides and proteins. SDS-PAGE and amino acid analysis suggested that EPS from both soft marine stromatolite and Schizothrix sp. mat contained small proteins (38 kD and 45 kD) enriched in aspartic acid and glutamic acid. Also, immuno blotting suggested that natural EPS contain high molecular weight acid polysaccharide (500 k) which may represent cross-linked products of laboratory cultured Schizothrix sp. acid polysaccharide (300 k). EPS from both soft marine stromatolite and laboratory cultured Schizothrix sp. inhibited CaCO3 precipitation in vitro, as determined using pH drift assays examining pH decrease which occur in response to CaCO3 precipitation. PH drift assays of enzymatically and chemically modified EPS isolated from soft marine stromatolite and laboratory cultured Schizothrix sp. indicated that both uronic acids and protein fractions may be involved in the inhibition of CaCO3 precipitation.     

Starvation-specific formation of a peripheral exopolysaccharide by a marine Pseudomonas sp., strain S9.

The marine bacterium Pseudomonas sp. strain S9 produces exopolysaccharides (EPS) during both growth and total energy source and nutrient starvation. Transmission electron microscopy of immunogold-labeled cells demonstrated that the EPS is closely associated with the cell surface during growth (integral EPS), while both the integral form and a loosely associated extracellular (peripheral) form were observed during starvation. Formation and release of the latter rendered the starvation medium viscous. In addition, after 3 h of starvation in static conditions, less than 5% of the cells were motile, compared with 100% at the onset of starvation and approximately 80% subsequent to release of the peripheral EPS at 27 h of starvation. Inhibition of protein synthesis with chloramphenicol added before 3 h of starvation caused no increase in viscosity. However, addition of chloramphenicol at 3 h did not prevent the subsequent increase in viscosity displayed by S9 cells. The amount of integral EPS increased for both nontreated and chloramphenicol-treated S9 cells during the first hour of starvation, with a subsequent equal decrease. The chloramphenicol-treated cells, as well as cells of a transposon-generated mutant strain deficient in peripheral EPS formation, remained adhesive to a hydrophobic inanimate surface during the initial 5 h of starvation, whereas nontreated wild-type cells had progressively decreased adhesion capacity. During the initial 5 h of starvation, most of the nontreated cells but only a small fraction of the chloramphenicol-treated and mutant cells detached from the hydrophobic substratum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Starvation-specific formation of a peripheral exopolysaccharide by a marine Pseudomonas sp., strain S9

The marine bacterium Pseudomonas sp. strain S9 produces exopolysaccharides (EPS) during both growth and total energy source and nutrient starvation. Transmission electron microscopy of immunogold-labeled cells demonstrated that the EPS is closely associated with the cell surface during growth (integral EPS), while both the integral form and a loosely associated extracellular (peripheral) form were observed during starvation. Formation and release of the latter rendered the starvation medium viscous. In addition, after 3 h of starvation in static conditions, less than 5% of the cells were motile, compared with 100% at the onset of starvation and approximately 80% subsequent to release of the peripheral EPS at 27 h of starvation. Inhibition of protein synthesis with chloramphenicol added before 3 h of starvation caused no increase in viscosity. However, addition of chloramphenicol at 3 h did not prevent the subsequent increase in viscosity displayed by S9 cells. The amount of integral EPS increased for both nontreated and chloramphenicol-treated S9 cells during the first hour of starvation, with a subsequent equal decrease. The chloramphenicol-treated cells, as well as cells of a transposon-generated mutant strain deficient in peripheral EPS formation, remained adhesive to a hydrophobic inanimate surface during the initial 5 h of starvation, whereas nontreated wild-type cells had progressively decreased adhesion capacity. During the initial 5 h of starvation, most of the nontreated cells but only a small fraction of the chloramphenicol-treated and mutant cells detached from the hydrophobic substratum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of chromium(VI) removal behaviour by two isolates of Synechocystis sp. in terms of exopolysaccharide (EPS) production and monomer composition

Chromium(VI) removal and its association with exopolysaccharide (EPS) production in cyanobacteria were investigated. Synechocystis sp. BASO670 produced higher EPS (548 mg L⁻¹) than Synechocystis sp. BASO672 (356 mg L⁻¹). While the EC₅₀ of the Cr(VI) for Synechocystis sp. BASO670 and Synechocystis sp. BASO672 were determined as 11.5 mg L⁻¹, and 2.0 mg L⁻¹, respectively, there was no relation between Cr(VI) removal and EPS production. Synechocystis sp. BASO672, which has higher EPS value, removed (33%) more Cr(VI) than Synechocystis sp. BASO670. Monomer compositions of EPS of each of the isolates were determined differently. Synechocystis sp. BASO672 which removed higher Cr(VI), had higher values of uronic acid and glucuronic acid (192 μg/mg and 89%, respectively). Our results showed that EPS might play a role in Cr(VI) tolerance. Monomer composition, especially uronic acid and glucuronic acid content of EPS may have enhanced Cr(VI) removal.     

Exopolysaccharide: a novel important factor in the microbial dissolution of tricalcium phosphate

Four strains (Enterobacter sp. EnHy-401, Arthrobacter sp.ArHy-505, Azotobacter sp.AzHy-510 and Enterobacter sp.EnHy-402) which have the ability to solubilize tricalcium phosphate (TCP) were used to study the mechanism of P-solubilization. It was found that three phosphate solubilizing bacteria (EnHy-401, ArHy-505 and AzHy-510) producing exopolysaccharide (EPS) have a stronger ability for P-solubilization than isolate EnHy-402 without EPS production, of those, the strain EnHy-401 with the highest EPS production and efficient organic acids on P-solubilization had a stronger capacity for P-solubilization than the others. Further studies demonstrated that addition of EPS into medium could increase the amount of phosphorus solubilized by organic acid, but failed to release phosphorus from TCP alone. The synergistic effects of EPS and organic acid on TCP solubilization varied with the origin and the concentration of EPS in medium. EPS produced by EnHy-401 was most effective in promoting phosphorus release at an optimal concentration in medium. The increase of P-solubilization brought by EPS attributed to the participation of EPS led to the change in homeostasis of P-solubilization, pushing it towards P dissolved by holding free phosphorus in the medium, consequently resulting in greater phosphorus released from insoluble phosphate. We therefore suggest that EPS with ability of phosphorus-holding may be a novel important factor in the microbial dissolution of TCP except for organic acid.     

Responses of unsaturated Pseudomonas putida CZ1 biofilms to environmental stresses in relation to the EPS composition and surface morphology

The extracellular polymeric substance (EPS) and surface properties of unsaturated biofilms of a heavy metal-resistant rhizobacterium Pseudomonas putida CZ1, in response to aging, pH, temperature and osmotic stress, were studied by quantitative analysis of EPS and atomic force microscope. It was found that EPS production increased approximately linearly with culture time, cells in the air-biofilm interface enhanced EPS production and decreased cell volume to cope with nutrient depletion during aging. Low pH, high temperature and certain osmotic stress (120 mM NaCl) distinctly stimulated EPS production, and the main component enhanced was extracellular protein. In addition to the enhancement of EPS production in response to high osmotic (328 mM NaCl) stress, cells in the biofilm adhere tightly together to maintain a particular microenvironment. These results indicated the variation of EPS composition and the cooperation of cells in the biofilms is important for the survival of Pseudomonas putida CZ1 from environmental stresses in the unsaturated environments such as rhizosphere.     

Biochemical characterization of cyanobacterial extracellular polymers (EPS) from modern marine stromatolites (Bahamas)

A range of biochemical characterizations were used to examine the extracellular polymeric secretions (EPS) of two cyanobacteria, Synechocystis sp. and Oscillatoria sp., isolated from marine stromatolites, Bahamas. Two-dimensional gel electrophoresis was successfully used to fractionate proteins in EPS. The results suggest that cyanobacterial EPS is composed of a network of macromolecules having different biochemical properties, which may contribute to extracellular functions.