Biosorption of Cd(II), Ni(II) and Pb(II) from Aqueous Solution by Dried Biomass of Aspergillus niger: Application of Response Surface Methodology to the Optimization of Process Parameters

In this study, the biosorption of Cd(II), Ni(II) and Pb(II) on Aspergillus niger in a batch system was investigated, and optimal condition determined by means of central composite design (CCD) under response surface methodology (RSM). Biomass inactivated by heat and pretreated by alkali solution was used in the determination of optimal conditions. The effect of initial solution pH, biomass dose and initial ion concentration on the removal efficiency of metal ions by A. niger was optimized using a design of experiment (DOE) method. Experimental results indicated that the optimal conditions for biosorption were 5.22 g/L, 89.93 mg/L and 6.01 for biomass dose, initial ion concentration and solution pH, respectively. Enhancement of metal biosorption capacity of the dried biomass by pretreatment with sodium hydroxide was observed. Maximal removal efficiencies for Cd(II), Ni(III) and Pb(II) ions of 98, 80 and 99% were achieved, respectively. The biosorption capacity of A. niger biomass obtained for Cd(II), Ni(II) and Pb(II) ions was 2.2, 1.6 and 4.7 mg/g, respectively. According to these observations the fungal biomass of A. niger is a suitable biosorbent for the removal of heavy metals from aqueous solutions. Multiple response optimization was applied to the experimental data to discover the optimal conditions for a set of responses, simultaneously, by using a desirability function.     

Effect of Aspergillus niger on weathering of phosphorite rock

Weathering mechanism of phosphorite rock by Aspergillus niger has been studied. Ten strains of phosphate-solubilizing fungi were isolated from rhizosphere soils by using dilute plate method in solid inorganic phosphorus culture. According to the size of soluble phosphate circle in the medium, a strain of stronger phosphate-solubilizing fungus was acquired, which was identified as, Aspergillus niger using identification methods of morphology and ITS sequences comparison in Genbank. In liquid culture, incubation in static state, the weathering of apatite rock with the fungus by contrast method： putting apatite powder （200 mesh） in liquid culture medium of flask, inoculation fungus after autoclave （setting sterile control） for studying direct weathering process; putting dialysis bag with apatite powder （200 mesh） in liquid culture medium of flask, inoculation fungus after autoclave （setting sterile control） for studying indirect weathering process.     

Zeolite and fungi’s flocculability of simulated wastewater containing heavy metal ions or phosphorus

This paper focuses on the flocculability of simulated wastewater containing heavy metal ions (Fe3+, Cd2+) or phosphorus by zeolite, microbial flocculants (MBF) produced by Aspergillus niger and the composite flocculant composed of zeolite and MBF. The main results are presented as follows: zeolite was a good flocculant when the contamination of the three simulated wastewaters was low, but the treated water is of turbidness and the particles in it are hard to precipitate. The MBF have a good flocculability toward Fe3+ wastewater, as well as particulate matter. Significant changes in flocculability occurred after adding the composite flocculant in different simulated wastewaters, the best or least effect respective for Fe3+ and Cd2+ wastewater. The research we have done shows that the method by which the composite flocculant is used to treat the wastewater containing heavy metal ions or phosphorus provides important reference value for practical application.     

细菌和真菌对复合污染模拟废水的处理研究

本文利用胶质芽孢杆菌(Bacillus mucilaginosus)和黑曲霉(Aspergillus niger)处理铜-苯酚(简称铜-酚)和镉-苯酚(简称镉-酚)这类有机-无机复合污染模拟废水,采用胶质芽孢杆菌和黑曲霉分别单独、联合或先后处理等5种方式,探讨了这两类菌体对复合污染模拟废水的处理效果及优化方法。结果表明,微生物对铜-酚废水的处理效果优于对镉-酚废水。对于铜-酚废水的处理表明,当废水中苯酚浓度为50~200 mg/L时,去除率可达80%以上,最高可达94.65%,其中铜的去除率较苯酚低;当模拟废水中铜浓度为30 mg/L时,可达最高去除率(60.02%)。微生物对镉-酚废水的处理表明,当废水中镉离子浓度为4 mg/L时,最高去除率为58.44%,苯酚的去除率一直保持在30%左右。     

Genetic and meristic variation in black and smooth oreos in the New Zealand exclusive economic zone

Meristic and genetic methods were used to determine the stock relationships of black Allocytus niger (James, Inada & Nakamura, 1988) and smooth oreo Pseudocyttus maculatus (Gilchrist, 1906) in the New Zealand Exclusive Economic Zone (EEZ). Samples were collected from four management areas—OEO 1 (south‐west), OEO 3A (Chatham Rise west), OEO 4 (Chatham Rise east), and OEO 6 (subantarctic) during the 1998 October‐December spawning period. Lateral line scale counts and pyloric caeca counts revealed differences between black oreo samples from OEO 6 and the other three OEO management areas. Lateral line scale counts in smooth oreo showed no significant differences between areas. Genetic analyses of four non‐coding regions of nuclear DNA and mitochondrial (mt) DNA haplotypes in black oreo showed no significant differentiation among the four management areas. Likewise for smooth oreo, genetic analyses of five non‐coding regions of nuclear DNA and mtDNA haplotypes showed no overall regional differentiation, although there was weak evidence at one locus for a difference between OEO 3A and OEO 6. The data do not reject the null hypothesis of a single genetic stock in New Zealand waters, and are typical of marine species with long pelagic juvenile stages.     

黑曲霉对含钾矿物的解钾作用与机理分析

通过测定黑曲霉(Aspergillus niger)对含钾矿粉的解钾量、黑曲霉作用含钾矿粉后的代谢产物(多糖、蛋白质、小分子分泌物)以及微环境中的pH值等,比较静置培养和震荡培养条件下黑曲霉对含钾矿粉的作用效果,并分析震荡培养下黑曲霉对含钾矿粉的风化作用机理。结果显示,震荡培养下黑曲霉对含钾矿粉的转化作用显著大于静置培养,震荡培养下黑曲霉作用含钾矿粉与否导致培养液中的代谢产物以及真菌-矿物聚集体微环境中pH值有显著改变。分析表明,黑曲霉生长形成的真菌-矿物聚集体、黑曲霉菌丝生长及其代谢产物、酸性微环境在含钾矿粉转化过程中发挥重要作用;黑曲霉对含钾矿粉的解钾作用应该是多种因素协同作用导致的综合效果。研究结果对完善真菌风化含钾矿物的作用机理,有效利用微生物转化低品位矿物钾技术提供了参考。     

Age and life histories of black and smooth oreos inferred using bomb radiocarbon dating and stable isotope analysis

Black oreo (Allocyttus niger) and smooth oreo (Pseudocyttus maculatus) are commercially exploited deepwater fishes in New Zealand. They are considered to be long-lived with unvalidated maximum otolith growth zone counts of 153 years and 86 years, respectively. Bomb radiocarbon dating results supported the otolith age estimates for A. niger, but those for P. maculatus provided only partial support. Oxygen isotope (δ¹⁸O) results for A. niger otoliths suggested that juveniles were in near-surface waters and adults in depths of 700–1300 m. In contrast, P. maculatus otoliths suggested a variable depth history (500 to at least 1500 m) throughout life. Carbon isotope (δ¹³C) results showed a steady enrichment from core values to c. 20 years for both species, owing to changes in diet and metabolic rate from the juvenile to the adult fish, associated with a depth increase. Von Bertalanffy growth parameters are provided for both species.     

Weathering of phosphorus-bearing mineral powder and calcium phosphate by Aspergillus niger

The weathering of phosphorus-bearing mineral powder(PBMP) and calcium phosphate(CP) by Aspergillus niger was compared,and the mechanism involved was analyzed for the comprehensive utilization of PBMP.The concentration of water-soluble phosphorus(WSP),Mg2+,and Ca2+at different culture times,microstructures of particles,and mineral compositions was examined by ultraviolet-visible spectrometer(UV),atomic absorption spectrometry(AAS),scanning electron microscopy(SEM),and X-ray diffraction(XRD).Results showed that the change in the concentrations of WSP,Mg2+,and Ca2+were related to the growth of A.niger and the different mineral compositions.Compared with CP,PBMP was weathered harder by fungi.Traces of the weathered mineral were found through SEM.CP not only showed traces of erosion damage but also appeared as a rhombohedron-like substance.The XRD test indicated that the weathering minerals can form water calcium oxalate.Further analysis revealed that the mechanism of PBMP and CP weathering by A.niger was the collaborative result of mycelium biomechanical effects and the acid-soluble role of acidic metabolites.The phosphorus dissolution rate of PBMP after 20 d was 46.83%,whereas that of CP after 12 d was 91.01%.The findings of this study are significant to the effective use of waste PBMP and to the exploitation of low-grade phosphate rock resources.     

细菌与真菌对黑云母的风化作用比较:以胶质芽孢杆菌和黑曲霉为例

以胶质芽孢杆菌(Bacillus mucilaginosus)与黑曲霉(Aspergillus niger)为例,比较了细菌与真菌对黑云母风化作用的异同点,为研究微生物风化矿物的作用机制提供了实验依据。分别采用有氮培养基和察氏培养基作为胶质芽孢杆菌和黑曲霉的实验培养基,并以黑云母矿粉为钾源,培养5天后利用ICP-OES、SEM及酶活测定等方法,对发酵液中各种离子浓度、矿物表面形貌以及发酵液中碳酸酐酶(CA)活性进行检测。胶质芽孢杆菌与矿物通过多糖等黏性物质紧紧黏附在一起形成细菌-矿物复合体,而黑曲霉与矿物相互作用则形成了真菌-矿物聚集体。黑曲霉培养液中离子溶出量总体高于胶质芽孢杆菌培养液,其中Al 3+、Fe3+和K+含量分别高出约17、30和3mg/L;分泌的酸性物质的量和CA活性都明显高于胶质芽孢杆菌,表明黑曲霉拥有对矿物更强的风化能力。