JBB : Journal of Bioscience and Bioengineering

            

Journal of Bioscience and Bioengineering vol.121 cover

Journal of Bioscience and Bioengineering – Recent Articles

  • TORC1 activity is partially reduced under nitrogen starvation conditions in sake yeast Kyokai no. 7, Saccharomyces cerevisiae
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Nobushige Nakazawa, Aya Sato, Masahiro Hosaka

    Industrial yeasts are generally unable to sporulate but treatment with the immunosuppressive drug rapamycin restores this ability in a sake yeast strain Kyokai no. 7 (K7), Saccharomyces cerevisiae. This finding suggests that TORC1 is active under sporulation conditions. Here, using a reporter gene assay, Northern and Western blots, we tried to gain insight into how TORC1 function under nitrogen starvation conditions in K7 cells. Similarly to a laboratory strain, RPS26A transcription was repressed and Npr1 was dephosphorylated in K7 cells, indicative of the expected loss of TORC1 function under nitrogen starvation. The expression of nitrogen catabolite repression-sensitive genes, however, was not induced, the level of Cln3 remained constant, and autophagy was more slowly induced than in a laboratory strain, all suggestive of active TORC1. We conclude that TORC1 activity is partially reduced under nitrogen starvation conditions in K7 cells.





  • Biochemical characterization of a bifunctional acetaldehyde-alcohol dehydrogenase purified from a facultative anaerobic bacterium Citrobacter sp. S-77
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Kohsei Tsuji, Ki-Seok Yoon, Seiji Ogo

    Acetaldehyde-alcohol dehydrogenase (ADHE) is a bifunctional enzyme consisting of two domains of an N-terminal acetaldehyde dehydrogenase (ALDH) and a C-terminal alcohol dehydrogenase (ADH). The enzyme is known to be important in the cellular alcohol metabolism. However, the role of coenzyme A-acylating ADHE responsible for ethanol production from acetyl-CoA remains uncertain. Here, we present the purification and biochemical characterization of an ADHE from Citrobacter sp. S-77 (ADHES77). Interestingly, the ADHES77 was unable to be solubilized from membrane with detergents either 1% Triton X-100 or 1% Sulfobetaine 3-12. However, the enzyme was easily dissociated from membrane by high-salt buffers containing either 1.0 M NaCl or (NH4)2SO4 without detergents. The molecular weight of a native protein was estimated as approximately 400 kDa, consisting of four identical subunits of 96.3 kDa. Based on the specific activity and kinetic analysis, the ADHES77 tended to have catalytic reaction towards acetaldehyde elimination rather than acetaldehyde formation. Our experimental observation suggests that the ADHES77 may play a pivotal role in modulating intracellular acetaldehyde concentration.





  • Purification and enzymatic characterization of a novel β-1,6-glucosidase from Aspergillus oryzae
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Akira Watanabe, Moe Suzuki, Seiryu Ujiie, Katsuya Gomi

    In this study, among the 10 genes that encode putative β-glucosidases in the glycoside hydrolase family 3 (GH3) with a signal peptide in the Aspergillus oryzae genome, we found a novel gene (AO090038000425) encoding β-1,6-glucosidase with a substrate specificity for gentiobiose. The transformant harboring AO090038000425, which we named bglH, was overexpressed under the control of the improved glaA gene promoter to form a small clear zone around the colony in a plate assay using 4-methylumbelliferyl β-d-glucopyranoside as the fluorogenic substrate for β-glucosidase. We purified BglH to homogeneity and enzymatically characterize this enzyme. The thermal and pH stabilities of BglH were higher than those of other previously studied A. oryzae β-glucosidases, and BglH was stable over a wide temperature range (4°C–60°C). BglH was inhibited by Hg2+, Zn2+, glucono-δ-lactone, glucose, dimethyl sulfoxide, and ethanol, but not by ethylenediaminetetraacetic acid. Interestingly, BglH preferentially hydrolyzed gentiobiose rather than other oligosaccharides and aryl β-glucosides, thereby demonstrating that this enzyme is a β-1,6-glucosidase. To the best of our knowledge, this is the first report of the purification and characterization of β-1,6-glucosidase from Aspergillus fungi or from other eukaryotes. This study suggests that it may be possible to find a more suitable β-glucosidase such as BglH for reducing the bitter taste of gentiobiose, and thus for controlling the sweetness of starch hydrolysates in the food industry via genome mining.





  • Improved conversion of cinnamaldehyde derivatives to diol compounds via a pyruvate decarboxylase-dependent mechanism in budding yeast
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Shunichi Miyakoshi, Yukari Negishi, Yusuke Sekiya, Satoshi Nakajima

    Cinnamaldehyde is stereospecifically converted to (2S,3R) 5-phenylpent-4-ene-2,3-diol, an important starting material for the synthesis of biologically active compounds, by the budding yeast Saccharomyces cerevisiae. Immobilization of the yeast in calcium alginate capsules suppressed the formation of by-products and increased accumulation of the diol compounds. The mechanism of cinnamaldehyde conversion was investigated by using recombinant strains of Escherichia coli and S. cerevisiae carrying the pyruvate decarboxylase gene PDC1. As a result, condensation of the substrate with acetaldehyde was enhanced by PDC and flow to the diol product was altered.





  • Glycerol acts as alternative electron sink during syngas fermentation by thermophilic anaerobe Moorella thermoacetica
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Zen-ichiro Kimura, Akihisa Kita, Yuki Iwasaki, Yutaka Nakashimada, Tamotsu Hoshino, Katsuji Murakami

    Moorella thermoacetica is an anaerobic thermophilic acetogen that is capable of fermenting sugars, H2/CO2 and syngas (H2/CO). For this reason, this bacterium is potentially useful for biotechnology applications, particularly the production of biofuel from CO2. A soil isolate of M. thermoacetica, strain Y72, produces both ethanol and acetate from H2/CO2; however, the maximum concentrations of these two products are too low to enable commercialization of the syngas fermentation process. In the present study, glycerol was identified as a novel electron sink among the fermentation products of strain Y72. Notably, a 1.5-fold increase in the production of ethanol (1.4 mM) was observed in cultures supplemented with glycerol during syngas fermentation. This discovery is expected to aid in the development of novel methods that allow for the regulation of metabolic pathways to direct and increase the production of desirable fermentative compounds.





  • Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry reveals the correlation between chemical compounds in Japanese sake and its organoleptic properties
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Kei Takahashi, Fumie Kabashima, Fumihiko Tsuchiya

    Japanese sake is a traditional alcoholic beverage composed of a wide variety of metabolites, which give it many types of tastes and flavors. Previously, we have reported that medium-chain fatty acids contribute to a fatty odor in sake (Takahashi, K., et al., J. Agric. Food Chem., 62, 8478–8485, 2014). In this study, we have reanalyzed the data obtained using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry. The relationship between the chemical components in sake and specific organoleptic properties such as off-flavor and quality has been explored. This led to the identification of the type of chemical compounds present and an assessment of the numerous candidate compounds that correlate with such organoleptic properties in sake. This research provides important fundamental knowledge for the sake-brewing industry.





  • Formation of ethyl ferulate from feruloylated oligosaccharide by transesterification of rice koji enzyme under sake mash conditions
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Nobukazu Suzuki, Toshihiko Ito, Kai Hiroshima, Tetsuo Tokiwano, Katsumi Hashizume

    Formation of ethyl ferulate (EF) and ferulic acid (FA) under sake mash conditions was studied using feruloylated oligosaccharide (FO), prepared from rice grains, as the substrate for rice koji enzyme. EF and FA were produced from FO over six times faster than from alkyl ferulates however, under the same ethanol concentration, only small differences were observed between the EF/FA ratios when either FO or methyl ferulate were used as substrates. Esterification and hydrolysis of FO or methyl ferulate showed similar pH dependencies and similar EF/FA ratios for each substrate in all of the pH ranges tested. Ethanol concentration clearly affected the EF/FA ratio; the ratio increased as ethanol concentration increased. Formation of EF and FA in the sake mash simulated rice digest was accelerated by addition of exogenous FO. These results indicated that supply of FO to sake mash is a crucial step for EF and FA formation, and ethanol is an influencing factor in the EF/FA ratio. The rice koji enzyme reaction suggested that EF and FA are formed through a common feruloylated enzyme intermediate complex by transesterification or hydrolysis, and these reactions occur competitively.





  • Bacterial community structure and predicted alginate metabolic pathway in an alginate-degrading bacterial consortium
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Akihisa Kita, Toyokazu Miura, Satoshi Kawata, Takeshi Yamaguchi, Yoshiko Okamura, Tsunehiro Aki, Yukihiko Matsumura, Takahisa Tajima, Junichi Kato, Naomichi Nishio, Yutaka Nakashimada

    Methane fermentation is one of the effective approaches for utilization of brown algae; however, this process is limited by the microbial capability to degrade alginate, a main polysaccharide found in these algae. Despite its potential, little is known about anaerobic microbial degradation of alginate. Here we constructed a bacterial consortium able to anaerobically degrade alginate. Taxonomic classification of 16S rRNA gene, based on high-throughput sequencing data, revealed that this consortium included two dominant strains, designated HUA-1 and HUA-2; these strains were related to Clostridiaceae bacterium SK082 (99%) and Dysgonomonas capnocytophagoides (95%), respectively. Alginate lyase activity and metagenomic analyses, based on high-throughput sequencing data, revealed that this bacterial consortium possessed putative genes related to a predicted alginate metabolic pathway. However, HUA-1 and 2 did not grow on agar medium with alginate by using roll-tube method, suggesting the existence of bacterial interactions like symbiosis for anaerobic alginate degradation.





  • Enhanced volatile fatty acids production of waste activated sludge under salinity conditions: Performance and mechanisms
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Gaoqiang Su, Shuying Wang, Zhiguo Yuan, Yongzhen Peng

    Volatile fatty acids (VFAs) are essential for removing biological nitrogen and phosphorus in wastewater treatment plants. The purpose of this work was to investigate whether and how the addition of NaCl could improve the production of VFAs from waste activated sludge (WAS). Sludge solubilization was efficiently improved by the addition of NaCl. Both protein and carbohydrate in the fermentation liquid increased with the dosage of NaCl, and it provided a larger amount of organic compounds for the production of the VFAs. NaCl had inhibitory effects on the production of methane and a high dosage of NaCl could severely suppress the growth of methanogens, which decreased the consumption of the VFAs. Consequently, the production of VFAs was significantly enhanced by the addition of NaCl. The maximum production of VFAs was achieved with the highest dosage of NaCl (3316 mg (COD)/L at the NaCl dosage 0.5 mol/L; 783 mg (COD)/L without the addition of NaCl). Therefore, this study indicates that using NaCl could be an efficient method for improving the production of VFAs from WAS.





  • Utilization of biodiesel by-products for mosquito control
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Megha Pant, Satyawati Sharma, Saurabh Dubey, Satya Narayan Naik, Phool Kumar Patanjali

    The current paper has elaborated the efficient utilization of non-edible oil seed cakes (NEOC), by-products of the bio-diesel extraction process to develop a herbal and novel mosquitocidal composition against the Aedes aegypti larvae. The composition consisted of botanical active ingredients, inerts, burning agents and preservatives; where the botanical active ingredients were karanja (Pongamia glabra) cake powder and jatropha (Jatropha curcas) cake powder, products left after the extraction of oil from karanja and jatropha seed. The percentage mortality value recorded for the combination with concentration, karanja cake powder (20%) and jatropha cake powder (20%), 1:1 was 96%. The coil formulations developed from these biodiesel by-products are of low cost, environmentally friendly and are less toxic than the synthetic active ingredients.





  • Extracellular production of Pseudozyma (Candida) antarctica lipase B with genuine primary sequence in recombinant Escherichia coli
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Ayana Ujiie, Hideo Nakano, Yugo Iwasaki

    An Escherichia coli expression system was established to produce recombinant extracellular Pseudozyma (Candida) antarctica lipase B (CALB). With the aim of producing the genuine CALB without additional amino acid residues, the mature portion of the CALB gene was fused seamlessly to a pelB signal sequence and expressed in E. coli BL21(DE3) using the pET system. Inducing gene expression at low temperature (20°C) was crucial for the production of active CALB; higher temperatures caused inclusion body formation. Prolonged induction for 48 h at 20°C allowed for the enzyme to be released into the culture medium, with more than half of the activity detected in the culture supernatant. A catalytically inactive CALB mutant (S105A) protein was similarly released, suggesting that the lipid-hydrolyzing activity of the enzyme was not the reason for the release. The CALB production level was further improved by optimizing the culture medium. Under the optimized conditions, the CALB in the culture supernatant amounted to 550 mg/L. The recombinant CALB was purified from the culture supernatant, yielding 5.67 mg of purified CALB from 50 mL of culture. N-terminal sequencing and ESI-MS analyses showed proper removal of the pelB signal sequence and the correct molecular weight of the protein, respectively, confirming the structural integrity of the recombinant CALB. The kinetic parameters towards p-nitrophenylbutyrate and the enantiomeric selectivity on rac-1-phenylethylacetate of the recombinant CALB were consistent with those of the authentic CALB. This is the first example of E. coli-based extracellular production of a CALB enzyme without extra amino acid residues.





  • Investigating the role of co-substrate–substrate ratio and filter media on the performance of anammox hybrid reactor treating nitrogen rich wastewater
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Swati Tomar, Sunil Kumar Gupta

    This study explored the feasibility of using the anammox hybrid reactor (AHR), which combines suspended and attached growth media, for the biodegradation of ammonical nitrogen in wastewater. The study was performed in four laboratory-scale AHRs, inoculated with mixed seed culture (1:1). The anammox process was established by feeding the AHR with synthetic wastewater, containing NH4–N and NO2–N (1:1), at hydraulic retention time (HRT) of 1 day. The reactors were gradually acclimated to a higher ammonium concentration (1200 mg/l) until the pseudo-steady state was attained. Subsequently, the reactors were operated at various HRTs (0.25–3.0 days) to optimize the HRT and nitrogen loading rate (NLR). The study demonstrated that HRT of 1 day, corresponding to 95.1% of nitrogen removal was optimal. Pearson correlation analysis indicated the strong and positive correlation of HRT and sludge retention time (SRT), whereas the NLR and biomass yield correlated negatively with the nitrogen removal efficiency (NRE). The mass balance of nitrogen showed that a major fraction (79.1%) of the input nitrogen was converted into N2 gas, and 11.25% was utilized in synthesizing the biomass. The filter media in the AHR contributed to an additional 15.4% of ammonium removal and a reduction of 29% in the sludge washout rate. The nitrogen removal kinetics in the AHR followed the modified Stover–Kincannon model, whereas the Lawrence–McCarty model best described the bacterial growth kinetics. The study concludes that the hybrid configuration of the reactor demonstrated promising results and could be suitably applied for industrial applications.





  • Characteristics of human cell line, F2N78, for the production of recombinant antibody in fed-batch and perfusion cultures
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Joon Serk Seo, Byung Sub Min, Young-Bum Kwon, Soo-Young Lee, Jong-Moon Cho, Keun-Hee Park, Yae Ji Yang, Ki Eun Maeng, Shin-Jae Chang, Dong-Il Kim

    A human hybrid cell line, F2N78, was developed by somatic fusion of HEK293 and Namalwa cells for the production recombinant biopharmaceutical proteins. In this study, we performed perfusion culture to verify its potential in culture process used for human cell expression platform. Cell viability could be maintained over 90% and high viable cell density was obtained at higher than 1.0 × 107 cells/mL by bleeding process in perfusion culture. The cells were adapted well in both culture modes, but there were apparent differences in protein quality. Compared to fed-batch culture, degalactosylated forms such as G0F and G0 as well as Man5 showed no significant increases in perfusion culture. In terms of charge variants, acidic peaks increased, whereas main peaks constantly decreased according to the length of culture period in both methods.





  • Oriented growth and transdifferentiation of mesenchymal stem cells towards a Schwann cell fate on micropatterned substrates
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Anup D. Sharma, Svitlana Zbarska, Emma M. Petersen, Mustafa E. Marti, Surya K. Mallapragada, Donald S. Sakaguchi

    While Schwann cells (SCs) have a significant role in peripheral nerve regeneration, their use in treatments has been limited because of lack of a readily available source. To address this issue, this study focused on the effect of guidance cues by employing micropatterned polymeric films to influence the alignment, morphology and transdifferentiation of bone marrow-derived rat mesenchymal stem cells (MSCs) towards a Schwann cell-like fate. Two different types of polymers, biocompatible polystyrene (PS) and biodegradable poly(lactic acid) (PLA) were used to fabricate patterned films. Percentages of transdifferentiated MSCs (tMSCs) immunolabeled with SC markers (α-S100β and α-p75NTR) were found to be similar on patterned versus smooth PS and PLA substrates. However, patterning had a significant effect on the alignment and elongation of the tMSCs. More than 80% of the tMSCs were oriented in the direction of microgrooves (0°–20°), while cells on the smooth substrates were randomly oriented. The aspect ratio [AR, ratio of length (in direction of microgrooves) and breadth (in direction perpendicular to microgrooves)] of the tMSCs on patterned substrates had a value of approximately five, as compared to cells on smooth substrates where the AR was one. Understanding responses to these cues in vitro helps us in understanding the behavior and interaction of the cells with the 3D environment of the scaffolds, facilitating the application of these concepts to designing effective nerve guidance conduits for peripheral nerve regeneration.





  • Vascular-like network prepared using hollow hydrogel microfibers
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Takayuki Takei, Zyunpei Kitazono, Yoshihiro Ozuno, Takuma Yoshinaga, Hiroto Nishimata, Masahiro Yoshida

    One major challenge in the field of tissue engineering was the creation of volumetric tissues and organs in vitro. To achieve this goal, the development of a three-dimensional vascular-like network that extended throughout the tissue-engineered construct was essential to supply sufficient oxygen and nutrients to all of the cells in the constructs. For sufficient oxygenation and nutrition of the tissue-engineered constructs, the distance between each microvessel-like channel in the network should ideally be within 100–200 μm. In addition, the medium or blood should be perfused through the microchannels as soon as possible after the seeding of cells into the templates (scaffolds) of the constructs. In the present study, we proposed a novel technique for fabricating an engineered vascular-like network that satisfied these two requirements. The network comprised assembled hollow alginate hydrogel microfibers with mammalian cells enclosed in the gel portions. We controlled the distance between each flow microchannel (hollow core portions and interspace of the microfibers) to be within 150 μm by using microfibers with a gel thickness of approximately 50 μm. Furthermore, we confirmed that medium could be perfused into the flow channels quickly (within 10 min) after immobilization of the cells in the assembly. A human hepatoblastoma cell line (HepG2) proliferated in the gel portions of the microfibers and maintained their specific function during perfusion culture for 7 days. These results showed that the novel vascular-like networks fabricated here had the potential to allow the creation of volumetric tissues in vitro.





  • Cytotoxicity of gold nanoparticles in human neural precursor cells and rat cerebral cortex
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Uhn Lee, Chan-Jong Yoo, Yong-Jung Kim, Young-Mi Yoo

    Nanoparticles are promising tools for the advancement of drug delivery, medical imaging, and as diagnostic sensor. Medical nanodevices should develop miniaturization, because it would be injected into a human body. Gold nanoparticles (GNPs) with different sizes and shapes have therapeutic potential as a result of their small size, robust nature, excellent biocompatibility and optical properties. However, the application of GNPs as medical nanodevices it is necessary to know the biodegradation, biocompatibility, and development of surface coating which avoid the accumulation of nanoparticles. In this study, we carry out an in vitro toxicity and in vivo gene expression study using two kinds of GNPs. We found that GNPs toxicity is dependent on the dose or size administrated after the injected GNPs into the brain, and small particle size GNPs appeared more nestin expression compared to large particle size at short term implantation. These findings of toxicity of GNPs may play an important role in development of in vivo tools for the safety of GNPs.





  • Isolation and analysis of polysaccharide showing high hyaluronidase inhibitory activity in Nostochopsis lobatus MAC0804NAN
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Yuji Yamaguchi, Mamoru Koketsu

    An active substance with high hyaluronidase inhibitory effect was isolated from the edible cyanobacterium Nostochopsis lobatus MAC0804NAN strain and characterized. The active component in the hot water extract was purified by anion exchange and gel filtration chromatography and was found to be a polysaccharide. The IC50 against hyaluronidase of the purified polysaccharide was 7.18 μg/ml whose inhibitory activity is 14.5 times stronger than that of disodium cromoglycate (DSCG), an anti-allergy medication. The carbohydrate composition which was analyzed by GC–MS and NMR was found to be composed mainly of glucose, glucuronic acid, fucose, 2-O-methylfucose, mannose, galactose and xylose.





  • Extra-facile chiral separation of amino acid enantiomers by LC-TOFMS analysis
    Publication date: March 2016
    Source:Journal of Bioscience and Bioengineering, Volume 121, Issue 3

    Author(s): Yutaka Konya, Takeshi Bamba, Eiichiro Fukusaki

    An extra-facile chiral liquid chromatography-time of flight mass spectrometry (LC-TOFMS) analytical method of amino acid enantiomers has been developed without a derivatization process. The enantioseparation of eighteen proteinogenic amino acids (except for proline) was simultaneously performed using a combination of a chiral column (CROWNPAK CR-I(+)) and a TOFMS within 15 min. An isocratic condition of a simple mobile phase comprising acetonitrile/water/trifluoroacetic acid (96/4/0.5) gave baseline separation of all underivatized amino acid enantiomers on the chiral column.





  • Random Sample Consensus combined with Partial Least Squares regression (RANSAC-PLS) for microbial metabolomics data mining and phenotype improvement
    Publication date: Available online 6 February 2016
    Source:Journal of Bioscience and Bioengineering

    Author(s): Shao Thing Teoh, Miki Kitamura, Yasumune Nakayama, Sastia Putri, Yukio Mukai, Eiichiro Fukusaki

    In recent years, the advent of high-throughput omics technology has made possible a new class of strain engineering approaches, based on identification of possible gene targets for phenotype improvement from omic-level comparison of different strains or growth conditions. Metabolomics, with its focus on the omic level closest to the phenotype, lends itself naturally to this semi-rational methodology. When a quantitative phenotype such as growth rate under stress is considered, regression modeling using multivariate techniques such as partial least squares (PLS) is often used to identify metabolites correlated with the target phenotype. However, linear modeling techniques such as PLS require a consistent metabolite-phenotype trend across the samples, which may not be the case when outliers or multiple conflicting trends are present in the data. To address this, we proposed a data-mining strategy that utilizes random sample consensus (RANSAC) to select subsets of samples with consistent trends for construction of better regression models. By applying a combination of RANSAC and PLS (RANSAC-PLS) to a dataset from a previous study (gas chromatography/mass spectrometry metabolomics data and 1-butanol tolerance of 19 yeast mutant strains), new metabolites were indicated to be correlated with tolerance within certain subsets of the samples. The relevance of these metabolites to 1-butanol tolerance were then validated from single-deletion strains of corresponding metabolic genes. The results showed that RANSAC-PLS is a promising strategy to identify unique metabolites that provide additional hints for phenotype improvement, which could not be detected by traditional PLS modeling using the entire dataset.





  • Isolation and characterization of wound-induced compounds from the leaves of Citrus hassaku
    Publication date: Available online 4 February 2016
    Source:Journal of Bioscience and Bioengineering

    Author(s): Tomonori Asai, Tetsuya Matsukawa, Atsushi Ishihara, Shin'ichiro Kajiyama

    Citrus plants are world widely cultivated as horticultural tree crops, and nowadays their pharmacological activities have been well studied. Since research of defense responses in citrus plants have been mainly focused on the post-harvested fruits because of their commercial importance, defense mechanisms during their developmental stages have not been well understood. In the present study, two wound-induced compounds were isolated from leaves of Citrus hassaku, and their structures were elucidated by high-resolution electron spray ionization mass spectra (HRESIMS) and nuclear magnetic resonance (NMR) analyses. One of these compounds was identified as a known flavanone, hesperetin. The other was characterized as a novel furofuran lignan, and was named ‘biscitrusnin-A’. Their antimicrobial activities were also evaluated.