Polysaccharide differences between planktonic and biofilm-associated EPS from Pseudomonas fluorescens B52

The polysaccharides associated with free (planktonic) and surface-attached (biofilm) cells from cultures of Pseudomonas fluorescens strain B52 were compared. Variations in the attached matrix due to surface material (glass or stainless steel) were also analyzed. Two digestion methods were used to optimize the recoveries of sugars, uronic acids and acidic substituents. The yield of analyzable material after digestion reached 90% for the material associated to the biofilms, though only 20–30% for that bound to planktonic cells. The polysaccharide(s) in the biofilm had glucuronic and guluronic acids as main components, besides rhamnose, glucose and glucosamine. The proportion of glucuronic to guluronic acid was higher in the polysaccharide(s) found in biofilms formed on stainless steel than in those on glass.     

Effect of environmental factors and carbohydrate on gellan gum production

Submerged culture fermentation studies were carried out in batch mode for optimizing the environmental parameters and carbon source requirement by Pseudomonas elodea for the production of gellan gum. The maximum production of gellan gum was obtained with 16-h-old culture and 8% inoculum at 30°C and pH 7.0 after 52 h of incubation (6.0 g/L). Of the various carbon sources tested, 2% sucrose, glucose, and soluble starch yielded considerably high amounts of gellan. Studies on the concentration of various carbohydrates on gellan gum production indicated that the optimum concentration of glucose and starch was 3%, whereas for sucrose it was 4%. The addition of glucose in the medium above 3% had a detrimental effect on gellan yield. The investigation of intermediate two-step addition of glucose under identical conditions of fermentation showed an enhanced production of gellan (8.12 g/L) as compared with the control (6.0 g/L). To optimize the recovery of gellan from fermented broth, different solvents were tested for precipitation of gellan gum. Among the various solvents tested, tetrahydrofuran gave better recovery of gellan (82%) as compared with the conventional solvent isopropanol (49%).     

Comparative study of biosurfactant produced by microorganisms isolated from formation water of petroleum reservoir

Biosurfactant produced by Pseudomonas aeruginosa, Bacillus subtilis and Rhodococcus erythropolis that isolated from the formation water of Chinese petroleum reservoir has been compared in surface abilities and oil recovery. Maximum biosurfactant production reached to about 2.66 g/l and the surface tension of liquid decreased from 71.2 to 22.56 mN/m using P. aeruginosa. Three strains exhibited a good ability to emulsify the crude oil, and biosurfactant of P. aeruginosa attained an emulsion index of 80% for crude oil which was greater than other strains. Stability studies were carried out under the extreme environmental conditions, such as high temperature, pH, salinity and metal ions. Results showed an excellent resistance of all biosurfactants to retain their surface-active properties at extreme conditions. It was found that the biosurfactants from three isolated bacteria showed a good stability above pH of 5, but at lower pH (from 1 to 5) they will harmfully be affected. They were able to support the condition up to 20 g/l salinity. P. aeruginosa biosurfactant was even stable at the higher salinity. Regarding temperature, all produced biosurfactants demonstrated a good stability in the temperature up to 120 °C. But stability of three biosurfactants was affected by monovalent and trivalent ions. Oil recovery experiments in physical simulation showed 7.2-14.3% recovery of residual oil after water flooding when the biosurfactant of three strains was added. These results suggest that biosurfactants of these indigenous isolated strains are appropriate candidates for enhanced oil recovery with a preference to biosurfactant of P. aeruginosa.     

Increasing the antibacterial activity of gallium(III) against Pseudomonas aeruginosa upon coordination to pyridine-derived thiosemicarbazones

Reaction of N(4)-phenyl-2-formylpyridine thiosemicarbazone (H2Fo4Ph), N(4)-phenyl-2-acetylpyridine thiosemicarbazone (H2Ac4Ph) and N(4)-phenyl-2-benzoylpyridine thiosemicarbazone (H2Bz4Ph) with gallium nitrate gave [Ga(H2Fo4Ph)₂](NO₃)₃ (1), [Ga(2Ac4Ph)₂]NO₃ (2) and [Ga(2Bz4Ph)₂]NO₃ (3). In all complexes coordination of the thiosemicarbazone via the N_py–N–S chelating system occurs. In 1 the thiosemicarbazone acts as a neutral ligand while in 2 and 3 the ligand is anionic. Upon slow diffusion of 2 in DMSO [Ga(2Ac4Ph)₂]NO₃·DMSO (2a) was formed. The crystal structure of 2a was determined. Upon coordination the antibacterial activity of both gallium and thiosemicarbazones against Pseudomonas aeruginosa significantly increases.     

Measurement of attachment force of microbial cells

A parallel-plate flow chamber consisting of two transparent electro-conductive glass plates was constructed. The two glass plates were set parallel to each other and connected to a potentiostat apparatus to regulate the strength of the electric field between the plates. A microbial cell suspension was flowed through the chamber. This system enabled the application of an electrostatic force to suspend charged particles, e.g. microbial cells, existing between the two plates. The time course of the cell attachment of Pseudomonas syringae pv. atropurpurea NIAES 1309 suspended in 10 mM phosphate buffer solution (pH 7.0) to the glass plate was investigated at various electric field strengths ranging from −4.2 to +4.1 V cm⁻¹. The attachment rate and the maximum number of attached cells increased linearly with the increase in the strength of the positive electric field. In contrast, the rate and the number of cells decreased linearly with the decrease in the strength of the negative electric field. These linear relations gave a specific value for the strength of the electric field (−5.9 ± 0.7 V cm⁻¹) where the electrostatic repulsion and the microbial attachment force were thought to be equal, resulting in no cell attachment. From this value, the electrostatic repulsion, i.e. the microbial attachment force, was calculated to be 5.0 × 10⁻¹¹ N cell⁻¹ for cells of average size.     

Copper(II) complex of 3-cinnamalideneacetylacetone: Synthesis and characterisation

A bidentate ligand derived from cinnamaldehyde and acetylacetone and its copper(II) complex have been synthesized and characterized by elemental analysis, UV-Vis, IR, ESR and magnetic susceptibility measurements. Magnetic susceptibility measurements, ESR and electronic spectral data indicate the presence of six coordinated Cu(II) ion. The ligand and complex are tested for antibacterial activity againstPseudomonas aeroginosa. They are found to show the antibacterial activity.     

Formation of Polyhydroxyalkanoate Blends by Pseudomonas pseudoalcaligenes M1-2 from Various Carbon Sources

ＩｎｔｒｏｄｕｃｔｉｏｎＰｏｌｙｈｙｄｒｏｘｙａｌｋａｎｏａｔｅｓ (ＰＨＡｓ)ａｒｅａｆａｍｉｌｙｏｆｉｎｔｒａｃｅｌｌｕｌａｒｂｉｏｐｏｌｙｍｅｒｓｓｙｎｔｈｅｓｉｚｅｄｂｙｍａｎｙｂａｃｔｅｒｉａａｓｉｎｔｒａｃｅｌｌｕｌａｒｃａｒｂｏｎａｎｄｅｎｅｒｇｙｓｔｏｒａｇｅｃｏｍｐｏｕｎｄｓ[1] .ＰＨＡｓｈａｖｅａｗｉｄｅｒａｎｇｅｏｆｐｈｙｓｉｃａｌｐｒｏｐｅｒｔｉｅｓｒａｎｇｉｎｇｆｒｏｍｂｒｉｔｔｌｅｔｏｆｌｅｘｉｂｌｅｔｏｅｌａｓｔｉｃ ,ｄｅｐｅｎｄｉｎｇｏｎｔｈｅｉｒｍｏｎｏｍｅｒｓｔｒ…     

D4S—6菌的生物学特性及种的鉴定

Ｄ４Ｓ－６菌根据常规的一些生物学特性，确定其为假单胞菌属；按照假单胞菌属分节检索表的要求，我们最终鉴定Ｄ４Ｓ－６ 菌为泡囊假单胞菌，它能有效地分解虾塘的有机污染物．     

碱性脂肪酶产生菌的筛选与产酶条件及酶学性质研究

作者从泸州油脂厂附近的土壤中,筛选到一株产碱性脂肪酶活性较高的细菌,经初步鉴定为假单胞菌(Pseudomonassp.).经对该菌株进行产酶条件和酶学性质研究发现,该菌株的最适产酶发酵培养基为(%):酵母浸出汁1.5,黄豆粉1,NaCl0.2,K2HPO40.2,NaH2PO40.2,MgSO4·7H2O0.01,初始pH8.5.100mL三角瓶装液10mL,30℃,150r/min摇床培养48h,酶活最高可达19.1U/mL.酶的最适反应温度40℃,最适pH8.5,该酶具有较好的热稳定性.