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Yu X.,Kunming University of Science and Technology | Zhao P.,Kunming University of Science and Technology | He C.,Kunming University of Science and Technology | Huang Z.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment
Bioresource Technology | Year: 2012

A novel green microalgae strain from Lake Fuxian has been isolated and identified as a potential feedstock for biodiesel production. The novel strain was named Monoraphidium sp. FXY-10 based on its morphological and genomic characterization. The lipid productivities, fatty acid profiles, and microalgae recovery efficiency (ηa) of FXY-10 were investigated and compared under autotrophic and heterotrophic conditions. FXY-10 under autotrophic conditions exhibited a higher cellular lipid content (56.8%) than those under heterotrophic conditions (37.56%). However, FXY-10 growing under heterotrophic conditions exhibited more than 20-fold increase in lipid productivity compared with that under autotrophic conditions (148.74mgL-1d-1 versus 6.88mgL-1d-1). Moreover, higher saturated and monounsaturated fatty acids (77.5%) of FXY-10 was obtained under heterotrophic culture conditions, suggesting its potential as a biodiesel feedstock. Gravity sedimentation was proposed as the harvesting biomass method based on the 97.9% microalgae recovery efficiency of heterotrophic cells after settling for 24h. © 2012 Elsevier Ltd. Source

Xie Z.,Yunnan Normal University | Zhang X.,Yunnan Normal University | Ding J.,Yunnan Normal University | Ding J.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment | And 6 more authors.
Applied Mechanics and Materials | Year: 2013

A lipase gene from sequencing genomic DNA of Bacillus subtilis strain I4 (I4-2) was cloned and expressed in E. coli. The deduced amino acid (aa) sequences for the lipase I4-2 was composed of 31-amino-acid signal sequence and a 181-amino-acid mature part, corresponding to a molecular mass (Mr) of 19.33 kDa. Based on the Mr and the protein sequence, the lipase I4-2 was belong to the lipase family1.4. The activity of the purified recombinant lipase I4-2 was apparently optimal at 45 °C and pH 7.0. The enzyme was stable at 25 °C, and more than 56% of the initial activity after incubation in buffer pH 7.0 for 120 min at 37 °C. In addition, lipase I4-2 was mixed with methanol (50, v/v) for 30 min and residual activity was 45%. lipase I4-2 can catalyzed biodiesel production from soybean oil at methanol: soybean (molar ratio of methanol to oil = 3:1), 10% n-hexane, 3.5% water. The results of GC-MS analysis demonstrated that a 3-stepwise process resulted in a 98% conversion yield after 8 h of reaction at 37 °C. © (2013) Trans Tech Publications, Switzerland. Source

Zhou J.,Yunnan Normal University | Zhou J.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment | Dong Y.,Liaocheng Vocational and Technical College | Li J.,Yunnan Normal University | And 12 more authors.
Journal of Microbiology and Biotechnology | Year: 2012

The α-galactosidase-coding gene agaAJB13 was cloned from Sphingomonas sp. JB13 showing 16S rDNA (1,343 bp) identities of ≤97.2% with other identified Sphingomonas strains. agaAJB13 (2,217 bp; 64.9% GC content) encodes a 738-residue polypeptide (AgaAJB13) with a calculated mass of 82.3 kDa. AgaAJB13 showed the highest identity of 61.4% with the putative glycosyl hydrolase family 36 α-galactosidase from Granulicella mallensis MP5ACTX8 (EFI56085). AgaAJB13 also showed <37% identities with reported protease-resistant or Sphingomonas α-galactosidases. A sequence analysis revealed different catalytic motifs between reported Sphingomonas α-galactosidases (KXD and RXXXD) and AgaAJB13 (KWD and SDXXDXXXR). Recombinant AgaAJB13 (rAgaAJB13) was expressed in Escherichia coli BL21 (DE3). The purified rAgaAJB13 was characterized using p-nitrophenyl-α-D-galactopyranoside as the substrate and showed an apparent optimum at pH 5.0 and 60°C and strong resistance to trypsin and proteinase K digestion. Compared with reported protease-resistant α-galactosidases showing thermolability at 50°C or 60°C and specific activities of <71 U/mg with or without protease treatments, rAgaAJB13 exhibited a better thermal stability (half-life of >60 min at 60°C) and higher specific activities (225.0-256.5U/mg). These sequence and enzymatic properties suggest AgaAJB13 is the first identified and characterized Sphingomonas α-galactosidase, and shows novel protease resistance with a potential value for basic research and industrial applications. © The Korean Society for Microbiology and Biotechnology. Source

Zhou J.,Yunnan Normal University | Zhou J.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment | Wu Q.,Yunnan Normal University | Wu Q.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment | And 14 more authors.
Folia Microbiologica | Year: 2014

A glycosyl hydrolase family 10 endoxylanase from Bacillus sp. HJ14 was grouped in a separated cluster with another six Bacillus endoxylanases which have not been characterized. These Bacillus endoxylanases showed less than 52 % amino acid sequence identity with other endoxylanases and far distance with endoxylanases from most microorganisms. Signal peptide was not detected in the endoxylanase. The endoxylanase was expressed in Escherichia coli BL21 (DE3), and the purified recombinant enzyme (rXynAHJ14) was characterized. rXynAHJ14 was apparent optimal at 62.5 °C and pH 6.5 and retained more than 55 % of the maximum activity when assayed at 40-75 °C, 23 % at 20 °C, 16 % at 85 °C, and even 8 % at 0 °C. Half-lives of the enzyme were more than 60 min, approximately 25 and 4 min at 70, 75, and 80 °C, respectively. The enzyme exhibited more than 62 % xylanase activity and stability at the concentration of 3-30 % (w/v) NaCl. No xylanase activity was lost after incubation of the purified rXynAHJ14 with trypsin and proteinase K at 37 °C for 60 min. Different components of oligosaccharides were detected in the time-course hydrolysis of beechwood xylan by the enzyme. During the simulated intestinal digestion phase in vitro, 11.5-19.0, 15.3-19.0, 21.9-27.7, and 28.2-31.2 μmol/mL reducing sugar were released by the purified rXynAHJ14 from soybean meal, wheat bran, beechwood xylan, and rapeseed meal, respectively. The endoxylanase might be an alternative for potential applications in the processing of sea food and saline food and in aquaculture as agastric fish feed additive. © 2014 Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i. Source

Zhou J.,Yunnan Normal University | Zhou J.,Key Laboratory of Yunnan for Biomass Energy and Biotechnology of Environment | Gao Y.,Yunnan Normal University | Dong Y.,Yunnan Normal University | And 10 more authors.
Journal of Industrial Microbiology and Biotechnology | Year: 2012

A xylanase-coding gene (xynAHJ3, 1,104 bp) was cloned from Lechevalieria sp. HJ3 harbored in a saline soil sampled from Heijing town, aka the "town of salt", on the famous "Silk Route of the South". The gene encodes a 367-residue polypeptide (XynAHJ3) with the highest identity of 74.0 % with the endoxylanase from Streptomyces thermocarboxydus HY-15. The coding sequence of the mature protein (without the predicted signal peptide from M1 to S22) of xynAHJ3 was expressed in Escherichia coli BL21 (DE3). The activity of the purified recombinant XynAHJ3 (rXynAHJ3) was apparently optimal at 70 °C and pH 6.0, retained greater than 55 % xylanase activity at a concentration of 0.2-2.0 M Na+ and 26 % at 4.0 M Na+ (pH 7.5 20 °C), and showed 110.2 and 44.2 % xylanase activities in the presence of 100 mM SDS (pH 6.0 37 °C) and 10 % ethanol (pH 5.0 37 °C), respectively. rXynAHJ3 activity was stable at 50 °C and pH 4.0-11.0 for more than 60 min, in trypsin or proteinase K at 20 °C for 24 h (pH 7.5), in 10 % ethanol (v/v) (pH 5.0) at 30 or 37 °C for 72 h, in 80 % ethanol (v/v) for 1 h, and in 0.6 or 3 M NaCl (20 °C, pH 7.5) for 72 h. Compared with the majority of xylanases with tolerance to ethanol, salt, SDS, or protease (Km values of 1.42-15.1 mg ml-1), rXynAHJ3 showed a low Km value (0.8 mg ml-1) and showed only limited amino acid sequence identity with those other xylanases (less than 47 %). © Society for Industrial Microbiology and Biotechnology 2012. Source

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