RESUMO
The mechanism of chromium accumulation and microstructure transformation of the fused yeast were studied in this paper.The result showed that the process of Cr6+ reduction and adsorption was accom-panied by the H+ consumption.The main adsorptive groups on the strain surface included amino,hydroxyl,phosphate group and amide,among which phosphate group played vital role in the chromium accumulation.The removal rate of chromium and reduction rate of hexavalent chromium declined 70% and 46%,respec-tively,when phosphate group was masked.During the adsorption process the chromium ions complexed on the surface of fused yeast was transported into the cell wall and combined with inclusion to form steady spe-cies and this took 90 min to reach the equilibrium.The biosorption and reduction of Cr on the cell surface would alter microstructure of cell surface,reduce cell membrane potential and increase cell membrane per-meability.
RESUMO
A new experiment curriculum system of environmental microbiology was established centering on applied microbiology in environmental protection field and emphasizing on design and research experi- ments to motivate the students’ interests for the course, which helped them to improve their ability of think- ing independently and creatively as well as their practicing ability.
RESUMO
The stability of microbial flocculant (MBF) produced by Aspergillus sojae and its application to municipal thickened sludge dewatering were studied. The results showed that the MBF had high heat and acid-base endurance with high flocculating activity in a wide range of pH from 1.5 to 12. The MBF retained 96% of flocculating activity after 35 days preservation at 4℃, but in different pH the flocculating activity difference was very apparent after 35 days store at room temperature. The experimental results also demon- strated that the MBF was better than PAM and PAC in reducing specific resistance filtration. The optimal dose of MBF used for intensifying thickened sludge dewatering is 7%(volume fraction). And the more the volume of sludge is treated, the less the cost of MBF for unit volume sludge treatment.
RESUMO
A biosurfactant-producing strain(S_6)was isolated from oil-containing wastewater in oxidation ditch and identified as Pseudomonas aeruginosa based on physiological and biochemical experiments and 16S rDNA sequence analysis.Infrared spectrum analysis revealed that S_6 produced glucolipid in the process of metabolism.It was observed that S_6 decreased the surface tension of water from 72 mN/m to 33.9 mN/m with the critical micelle concentration(CMC)of 50mg/L.The measurement of oil displacement and surface tension demonstrated that the fermented liquid had stable surface activity at varying range of salinity,pH,amount of dissolved oxygen.The optimal culture condition was obtained through orthogonal experiment:glucose 10g/L,urea 5g/L,KH_2PO_4 1g/L,liquor of microelement 2mL,pH 8.0,water 1000mL;and the biosurfactant production under optimal culture condition was 0.173g/L.
RESUMO
Effects of Cr 6+ concentration and culture time on four heavy metal removing strains,stability of these four strains removing Cr 6+,configuration changes inside or outside their cells,effects of Cr 6+ on soluble reductive sugar inside their cells,and effect of several factors on these strains had been studied,and the Cr 6+ resistance mechanisms of these strains have been discussed elementarily. The results showed that the Lethality of these strains caused by Cr 6+ was similar with one another, namely, increasing at first, then decreasing, and finally increasing again as culture time passed. Acclimatization of Candida sp. was better than Sporobolomycetaceae sp.,and the Cr 6+ resistance of Sporobolomycetaceae sp. 7-3 was the best of the four. The research also demonstrated that the metabolic activity of these strains had been influenced by Cr 6+ in a certain extent. Scanning electron microscopy,transmission electron microscopy,and atomic force microscopy observations approved that removal of Cr 6+ by Candida sp. was depended on both surface adsorption and intracellular accumulation. Effects of Cr 6+ concentration, pH, culture time, nitrogen source, carbon source and adsorption time on these strains are not the same.
