Hongli Yuan

Rhizobium huakuii sp. nov. Isolated from the Root Nodules of Astragalus sinicus

Nine bacterial strains isolated from root nodules of Astragalus sinicus were compared with 41 reference strains, including the type strains of the type species of the genera Rhizobium, Bradyrhizobium, and Agrobacterium, by performing a numerical analysis of 200 phenotype features. Representative strains belonging to different clusters were further compared with similar bacteria by using data from gel electrophoresis of whole-cell proteins, DNA G+C content data, and DNA-DNA hybridization data. The rhizobial strains isolated from nodules of A. sinicus constitute a distinct homology group that is quite different from previously described Rhizobium, Bradyrhizobium, and Agrobacterium species and from strains isolated from other Astragalus species. We propose the name Rhizobium huakuii sp. nov. for the strains isolated from A. sinicus. Type strain CCBAU 2609 (= 103) has been deposited in the Culture Collection of Beijing Agricultural University, Beijing, Peoples Republic of China.

PRODUCTION AND CHARACTERIZATION OF AN INTRACELLULAR BIOFLOCCULANT BY CHRYSEOBACTERIUM DAEGUENSE W6 CULTURED IN LOW NUTRITION MEDIUM

A novel intracellular bioflocculant (named MBF-W6) produced by Chryseobacterium daeguense W6 cultured in low nutrition medium was investigated in this study. The effects of carbon source, nitrogen source, C/N ratio, initial pH, inoculum size, culture temperature and shaking speed on MBF-W6 production were studied. Chemical analysis showed that the purified MBF-W6 was mainly composed of 32.4% protein, 13.1% polysaccharide and 6.8% nucleic acid. Fourier-transform infrared (FTIR) spectroscopy indicated the presence of carboxyl, hydroxyl, and methoxyl groups. The elemental analysis of purified MBF-W6 revealed that the mass proportion of C, H, O, N and S was 40.92:6.53:44.01:8.53:1.01 (w/w) correspondingly. MBF-W6 had good flocculating rate in Kaolin suspension without any cation addition. The highest flocculating rate of 96.9% was achieved under the optimal conditions (bioflocculant dosage 1.2 mg l(-1), pH 5.6 and temperature 15 degrees C).

Optimization of the biomass production of oil algae Chlorella minutissima UTEX2341

High production cost is a major obstacle to the extensive use of microalgae biodiesel. To cut the cost and achieve higher biomass productivity, Chlorella minutissima UTEX2341 was cultured under photoheterotrophic conditions. With the carbon, nitrogen and phosphorus concentration of 26.37, 2.61 and 0.03 g L⁻¹ d⁻¹ respectively, a maximum biomass productivity of 1.78 g L⁻¹ d⁻¹ was obtained, which was 59 times more than that cultured under autotrophic condition. The lipid productivity reached 0.29 g L⁻¹ d⁻¹, which was 11.9 times higher than the highest value reported by Oh et al. (2010). The conversion rate of microalgae lipids to FAME was found to be elevated from 45.65% to 62.97% and the FAME productivity increased from 1.16 to 180.68 mg L⁻¹ d⁻¹ after the optimization. 94% of the fatty acid of C. minutissima UTEX2341 was found to be composed of palmitic, oleic, linoleic and γ linoleic and the unsaturated fatty acids were the main parts (79.42%).

Characterization of bioflocculants from biologically aerated filter backwashed sludge and its application in dying wastewater treatment.

In this study, the feasibility of bioflocculant extraction from backwashing sludge to reduce its production costs was investigated. Results showed that ultrasound and base treatment could significantly enhance bioflocculant extraction efficiency, however, flocculating activity was affected. It was observed that bioflocculants extracted from sludge of pH 11.0 had no flocculating activity. In contrast, bioflocculants extracted from sludge of pH 5.0, named as M-1, had good flocculating activity. To further study the flocculating activity of M-1, factors such as bioflocculant dosage, temperature and pH of the reaction solution were tested. The optimal conditions were 6.0mg/l bioflocculant dosage and pH 5.0, at a temperature of 10 degrees C. Under these conditions, the flocculating rate of kaolin clay was 92.67%. The effectiveness of such bioflocculants in the decolorization of synthetically dyed wastewater was then examined. In flocculating methylene blue and fast blue in aqueous solutions, decolorization efficiency levels were 82.9% and 77.8%, respectively.

Lipid production combined with biosorption and bioaccumulation of cadmium, copper, manganese and zinc by oleaginous microalgae Chlorella minutissima UTEX2341.

Algae lipid production combined with heavy metal removal is a cost-effective and environment-friendly method for algae biofuel production and hazardous waste treatment. Chlorella minutissima UTEX 2341 had strong resistance to cadmium, copper, manganese and zinc ions under heterotrophic culture condition and could efficiently remove them through intracellular accumulation and extracellular immobilization. Meanwhile, lipid accumulation was not inhibited by heavy metals. Instead, the algae lipid content significantly increased by 21.07% and 93.90%, respectively with the addition of cadmium and copper. Furthermore, the heavy metal residue in lipid was within μg range and satisfied the commercial standard. This artificial wastewater-algae biofuel-heavy-metal integrated utilization technology offered a new alternative solution to the problems of energy shortage and environmental pollution.

Removal of nitrogen by heterotrophic nitrification–aerobic denitrification of a phosphate accumulating bacterium Pseudomonas stutzeri YG-24

Phosphate accumulating bacterium Pseudomonas stutzeri YG-24 exhibited efficient heterotrophic nitrification and aerobic denitrification ability. Single factor experiments showed that both heterotrophic nitrification and aerobic denitrification occurred with sodium citrate as carbon source and lower C/N ratio of 8. High average NH4(+)-N, NO2(-)-N and NO3(-)-N removal rates of 8.75, 7.51 and 7.73 mg L(-1)h(-1) were achieved. The application of strain YG-24 in wastewater samples resulted in TN, NH4(+)-N, NO2(-)-N, NO3(-)-N and P removal efficiencies of 85.28%, 88.13%, 86.15%, 70.83% and 51.21%. Sequencing and quantitative amplification by real-time PCR of napA, nirS and ppk showed that nitrogen removal pathway of strain YG-24 was achieved through heterotrophic ammonium nitrification coupled with fast nitrite denitrification (NH4(+)-N to NO2(-)-N and then to gaseous nitrogen) directly. These results demonstrated the strain as a suitable candidate to simultaneously remove both nitrogen and phosphate in wastewater treatment.

Significance evaluation of the effects of environmental factors on the lipid accumulation of Chlorella minutissima UTEX 2341 under low-nutrition heterotrophic condition.

The effects of a variety of environmental factors on lipid accumulation of Chlorella minutissima UTEX 2341 under low-nutrition conditions were investigated. The growth of UTEX 2341 reached the exponential phase on the 1st day in low-nutrition medium. And the highest biomass productivity of 3.07 g L(-1) d(-1) was achieved on the 2nd day. The optimum pH and temperature for lipid accumulation were 6 and 20 °C respectively. 43.69 g L(-1) of NaCl and 0.11 mmol L(-1) of Fe(III) resulted in higher lipid content, analyzed by Design-Expert. And then under nitrogen starvation stress, the lipid content reached 22.84%. Meanwhile, the lipid yield was 2.5 g L(-1). The yield coefficient against carbon was 0.36 g g(-1), which was 4.68 times as much as that in OM medium. With the high proportion of C16 and C18 in the lipids, C. minutissima UTEX 2341 was proved to be a potential option for renewable biodiesel production.

Lacibacter cauensis gen. nov., sp. nov., a novel member of the phylum Bacteroidetes isolated from sediment of a eutrophic lake

A novel strain, NJ-8(T), was isolated from sediment of the eutrophic Taihu Lake (China) and was subjected to a taxonomic study by using a polyphasic approach. The novel strain was aerobic and formed orange-pigmented colonies on R2A agar. Cells were Gram-negative single rods that were motile by means of gliding. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain NJ-8(T) belonged to the phylum Bacteroidetes, with Niastella yeongjuensis DSM 17621(T) (92.3 % gene sequence similarity) and Niastella koreensis DSM 17620(T) (92.0 % similarity) as its closest relatives. The major fatty acids (>5 % of the total) were iso-C(15 : 0) (27.8 %), iso-C(15 : 1) G (15.4 %), iso-C(17 : 0) 3-OH (14.5 %) and summed feature 3 (comprising C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH; 13.9 %). The genomic DNA G+C content was 46.6 mol%. Based on molecular and phenotypic data, strain NJ-8(T) is considered to represent a novel species of a new genus, for which the name Lacibacter cauensis gen. nov., sp. nov. is proposed. The type strain of the type species of the genus, Lacibacter cauensis, is NJ-8(T) (=CGMCC 1.7271(T)=NBRC 104930(T)).

Flavobacterium cauense sp. nov., isolated from sediment of a eutrophic lake

A Gram-negative, rod-shaped, yellow-pigmented bacterium, designated strain R2A-7(T), was isolated from sediment of the eutrophic Taihu Lake in Jiangsu Province, China. The isolate was subjected to a taxonomic study using a polyphasic approach. Phylogenetic analysis based on the 16S rRNA gene sequences placed strain R2A-7(T) within the genus Flavobacterium in the family Flavobacteriaceae. The highest sequence similarity was found with Flavobacterium saliperosum (98.3 %), followed by other Flavobacterium species with similarities <96.0 %. The major fatty acids (>5 %) were 15 : 0 iso, 17 : 1 iso omega9c, 17 : 0 iso 3-OH, 15 : 1 iso G and 15 : 0 iso 3-OH. The G+C content of the genomic DNA of strain R2A-7(T) was 37.7 mol%. The DNA-DNA relatedness value with F. saliperosum CGMCC 1.3801(T) was 40.6 %. Molecular and phenotypic data suggest that strain R2A-7(T) represents a novel species within the genus Flavobacterium, for which the name Flavobacterium cauense is proposed. The type strain is R2A-7(T) (=CGMCC 1.7270(T)=NBRC 104929(T)).

Degradation/solubilization of Chinese lignite by Penicillium sp. P6.

Penicillium sp. P6, isolated from coal mine soil at the Qiantong colliery, Liaoning Province, Northwest China, can degrade Chinese lignite in 36 h on a plate colony and in 48 h, using a four-day cultured cell-free filtrate. Results of elemental analysis and IR spectrometry indicated that solubilized products exhibited some alterations in comparison to the original lignite. The amount of fulvic acid extracted from the biodegraded lignite was high, and the molecular distribution of humic acids from biodegraded lignite changed distinctively in comparison to that extracted from control lignite, possibly due to the depolymerization associated with fungal biodegradation.