Ru-an Chi

Isolation of phosphate-solubilizing fungi from phosphate mines and their effect on wheat seedling growth.

Three phosphate-solubilizing fungi, identified as Penicillium expansum, Mucor ramosissimus, and Candida krissii, were isolated from phosphate mines (Hubei, People’s Republic of China) and characterized. All the isolates demonstrated diverse levels of phosphate-solubilizing capability in National Botanical Research Institute’s phosphate growth medium containing rock phosphate as sole phosphate source. Acidification of culture medium seemed to be the main mechanism for rock phosphate solubilization. Indeed, citric acid, oxalic acid, and gluconic acid were shown to be present in the culture medium inoculated with these isolates. Moreover, the isolates produced acid and alkaline phosphatases in culture medium, which may also be helpful for RP solubilization. A strong negative correlation between content of soluble phosphorus and pH (r = – 0.89; p < 0.01) in culture medium was observed in this study. All the isolates promoted growth, soil available phosphorus, phosphorus, and nitrogen uptake of wheat seedling in field soil containing rock phosphate under pot culture conditions, thus demonstrating the capability of these isolates to convert insoluble form of phosphorus into plant available form from rock phosphate, and therefore hold great potential for development as biofertilizers to enhance soil fertility and promote plant growth.

Simultaneous removal of cationic and anionic dyes by the mixed sorbent of magnetic and non-magnetic modified sugarcane bagasse

Magnetic carboxyl groups modified (MMS) and non-magnetic amine groups modified (AMS) sugarcane bagasse were prepared and mixed to remove cationic and anionic dye simultaneously from aqueous solution. For comparison, the adsorption performances of MMS, AMS and the mixed sorbent for basic magenta (cationic dye) and congo red (anionic dye) were investigated in the binary system. Zeta potential analysis showed that MMS was negatively charged and AMS was positively charged in the investigated pH range. The adsorption capacities of MMS for basic magenta and congo red were 1.24 and 0.04mmolg(-1), while those of AMS were 0.04 and 1.55mmolg(-1), respectively. Both of MMS and AMS had high adsorption capacity and affinity toward opposite-charged dye but low adsorption capacity and affinity toward similar-charged dye. Adsorption experiments in the binary system showed that only the mixed sorbent could remove the two dyes simultaneously from aqueous solution (removal efficiencies >90%). The amounts of basic magenta and congo red absorbed on the mixed sorbent both increased linearly with the increase of their initial concentrations in the investigated range. The dye loaded mixed magnetic and non-magnetic sorbents could be separated by a magnet. MMS and AMS could be regenerated by using acid and alkaline eluents, respectively. After regeneration, the MMS and AMS could be mixed again and used repeatedly. The mixed sorbent had great potential in practical dye waste water treatment.

Biosolubilization of Rock Phosphate by Three Stress-Tolerant Fungal Strains

Three stress-tolerant phosphate-solubilizing fungal strains identified as Aspergillus niger, Aspergillus japonicus, and Penicillium simplicissimum were isolated from wheat rhizospheric soil. The strains demonstrated different capabilities of phosphate solubilization in National Botanical Research Institute’s phosphate medium containing rock phosphate (RP) as sole phosphorus (P) source, and the solubilization of RP by P. simplicissimum was the most effective among these strains, followed by A. niger and A. japonicus. All the strains exhibited high levels of stress tolerance like 10∼45°C temperature, 4∼11 pH, 0∼3.5% NaCl, and 0∼35% PEG 10000. The strains also differed in their abilities to survive and release soluble P from RP under different stresses. A. niger showed significantly higher tolerance to temperature and pH over the other two strains. Higher amount of spores and content of soluble P in the medium were observed in the presence of 3.5% NaCl with P. simplicissimum, followed by A. niger and A. japonicus. P. simplicissimum could not solubilize RP in the presence of 35% PEG 10000, which exhibited the lowest tolerance to desiccation stress among the three strains.

Adsorption Behaviors of Puerarin on S-8 Macroporous Resin

Abstract To assess the adsorption properties of puerarin from Pueraria lobata on S-8 resin in the separation procedure and to optimize the column separation parameters, both static and kinetic adsorption of puerarin on S-8 resin were investigated. The results show that static adsorption behavior of puerarin is correlated with Langmuir adsorption isotherm equation, q e = 147.059 c e /(355.206 + c e ), and Freundlich adsorption isotherm equation, q e = 2.544 c e 0.561 . Liquid film diffusion is the control step of adsorption kinetics, and the adsorption kinetics behavior follows the Boyd equation. After purification with S-8 resin, the elution efficiency of puerarin is 84%, and the purity of product reaches 43.75% through detection by high-performance liquid chromatography (HPLC), when the optimum flow rate and concentration of elution are 2.5 mL·min −1 and 80% ethanol at room temperature.

Dynamic microwave-assisted extraction of total ginsenosides from ginseng fibrous roots

A dynamic microwave-assisted extraction (DMAE) method is established for the extraction of total ginsenosides from ginseng fibrous roots. The extraction process has been simulated and its main affection factors (liquid/solid ratio K of solvent to ginseng powders (V/m), irradiation time, irradiation temperature, extracting solution concentration, flow rate of solvent and microwave power) have been optimized by response surface methodology (RSM). The optimum conditions of extraction are the liquid/solid ratio of 270 mL/g, the extraction temperature of 75 °C, the extraction time of 35 min, ethanol concentration of 70% (V/V), the solvent flow rate of 1.3 mL/min, and the microwave power of 500 W. The yield of ginsenosides obtained by the proposed DAME method is (15.0±0.7) %, which is well agreement with the yield predicted by the model. Compared with static microwave-assisted extraction, DMAE has a higher extraction yield and can avoid the degradation of ginsenoside.

Effects of co-ion initial concentration ratio on removal of Pb2+ from aqueous solution by modified sugarcane bagasse

A modified sugarcane bagasse (SCB) fixed bed column was used to remove Pb2+ from aqueous solution. To determine the optimal condition for Pb2+ separation, Ca2+ was chosen as the model interfering ion, and effects of Ca2+ and Pb2+ initial concentration ratio (C0Ca: C0Pb) on the adsorption of Pb2+ were investigated. Results showed that adsorption amount ratio of Ca2+ and Pb2+ (qeCa: qePb) had a good linear relationship with C0Ca: C0Pb. Mass ratio of Pb2+ absorbed on the modified SCB was higher than 95% at C0Ca: C0Pb<1.95, illustrating that Pb2+ could be selectively removed from aqueous solution. To verify that, simulated waste water containing co-ions of K+, Na+, Cd2+ and Ca2+ was treated, and results showed that the equilibrium amount of Pb2+, K+, Na+, Cd2+ and Ca2+ adsorbed was 134.14, 0.083, 0.058, 1.28, and 1.28mg g−1, respectively, demonstrating that the modified SCB could be used to remove Pb2+ from aqueous solution in the investigated range.