M. Moo-young - Academia.edu (original) (raw)

Papers by M. Moo-young

Pure and Applied Chemistry, 1994

Lee (Republic of Korea); P. Adlercreutz (Sweden); 0. Yenigun (Turkey); P. N. Campbell (UK). ?The ... more Lee (Republic of Korea); P. Adlercreutz (Sweden); 0. Yenigun (Turkey); P. N. Campbell (UK). ?The Commission has chosen this series with a view to intensify the interrelations of chemistry and biotechnology. By improving the knowledge of chemists in the field of biotechnology it is hoped to initiate more ideas for applying biological methods in chemistry, inspire more use of chemical knowledge in the biological sciences and help scientists in both fields to work closer together. In the articles in the series, to be published in this journal, outstanding experts in their respective fields will give (a) an overview on topics related to the practical use of biotechnological methods in organic chemistry, (b) an outlook on upcoming research topics, their impact on existing areas and their potential for future developments. The Commission solicits comments as well as suggestions for future topics, and will aim to help in providing answers to any questions in this field. Names of countries given after Members' names are in accordance with the ZUPAC Handbook 1991-93; changes will be effected in the 1994-95 edition. Republication of this report is permitted without the need for formal IUPAC permission on condition that an acknowledgement, with full reference together with IUPAC copyright symbol (0 1994 IUPAC), is printed. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization.

Bioprocess Engineering, 1998

Recovery of the intracellular bioplastic poly(b-hydroxybutyric acid) or PHB from fed-batch cultur... more Recovery of the intracellular bioplastic poly(b-hydroxybutyric acid) or PHB from fed-batch cultured Alcaligenes latus, ATCC 29713, was examined using combinations of chemical and mechanical treatments to disrupt the cells. Chemical pretreatments used sodium chloride and sodium hydroxide. For salt pretreatment the cells were exposed to NaCl (8 kg m A3) and heat (60°C, 1 h), cooled to 4°C, and mechanically disrupted. For alkaline treatments, the cells were exposed to sodium hydroxide (0.025±0.8 kg NaOH per kg biomass) and mechanically disrupted at ambient temperature. A combined treatment with sodium chloride (8 kg m A3), heat (60°C, 1 h), and alkaline pH shock (pH 11.5, 1 min) was also tested. Mechanical disruption employed a continuous¯ow bead mill (2,800 rpm agitation speed, 90 ml min A1 slurry¯ow rate, 512 lm mean bead diameter, bead loadings of 80% or 85% of chamber volume). Disruption was quanti®ed by protein release. Over most of the disruption period, the release of PHB was approximately proportional to protein release. Regardless of the pretreatment or bead load, the disruption obeyed ®rst order kinetics; hence, the rate of protein release was directly proportional to the amount of unreleased protein. Relative to untreated biomass, pretreatment always produced earlier protein release during milling. Pretreatment with a minimum of 0.12 kg NaOH per kg biomass was necessary to enable complete disruption within three passes (85% bead load). Untreated biomass required more than twice as many passes. Irrespective of the chemical pretreatment, the bead loading strongly in¯uenced the disruption rate which was higher at the higher loading. Alkaline hydrolysis associated PHB loss was observed, but it could be limited to insigni®cant levels by immediate neutralization of disrupted homogenates.

Biotechnology Progress, 2000

The dependence of filamentous fungal protease secretion on morphology was investigated by employi... more The dependence of filamentous fungal protease secretion on morphology was investigated by employing the recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP] which contains a gene for the glucoamylase-GFP (green fluorescence protein) fusion protein. Different inoculum levels were used to obtain different sizes of pellet or free mycelia. The extracellular protease activity of the cultures varied with the pellet size and decreased dramatically when the morphology was changed from free mycelia to pellets. The culture with an optimal pellet size of 1.6 mm was obtained from an inoculum of 4 × 10 6 spores/mL. It resulted in a specific protease activity of 158 units/ L, only one-third of that in free mycelial growth, and a maximum specific GFP yield of 0.98 mg/g (cell mass) compared to 0.29 mg/g for free mycelial growth with an inoculum of 10 7 spores/mL. The results indicate that this bioprocessing strategy can be effectively used to inhibit protease activity in filamentous fungal fermentation and thereby to enhance heterologous protein production.

Bioprocess Engineering, 1997

l 1Ymax h À1 maximum speci®c growth rate for glucose fermentation l 2Ymax h À1 maximum speci®c gr... more l 1Ymax h À1 maximum speci®c growth rate for glucose fermentation l 2Ymax h À1 maximum speci®c growth rate for glucose oxidation l 3Ymax h À1 maximum speci®c growth rate for ethanol oxidation

Biotechnology Advances, 1996

Journal of Industrial Microbiology and Biotechnology, 2002

The effects of cell immobilization on the secretion of extracellular proteases and glucoamylase p... more The effects of cell immobilization on the secretion of extracellular proteases and glucoamylase production by Aspergillus niger were investigated under a variety of immobilization techniques and culture conditions. Immobilization was achieved by means of cell attachment on metal surfaces or spore entrapment and subsequent growth on porous Celite beads. Free-suspension cultures were compared with immobilized mycelium under culture conditions that included growth in shake flasks and an airlift bioreactor. Cell attachment on metal surfaces minimized the secretion of proteases while enhancing glucoamylase production by the fungus. Growth on Celite beads in shakeflask cultures reduced the specific activity of the secreted proteases from 128 to 61 U g-1 , while glucoamylase specific activity increased from 205 to 350 U g-1. The effect was more pronounced in bioreactor cultures. A reduction of six orders of magnitude in protease specific activities was observed when the fungus grew immobilized on a rolled metal screen, which served as the draft tube of an airlift bioreactor.

Chemical engineering science, 1987

Applied and environmental microbiology, 1978

The treatment of a hardwood sawdust with 1% NaOH solution at 121 degrees C dissolved 19.7% of the... more The treatment of a hardwood sawdust with 1% NaOH solution at 121 degrees C dissolved 19.7% of the dry matter, mainly hemicellulose and lignin. Fermentation of the treated solids by Chaetomium cellulolyticum for 48 h gave a product containing 12.5% crude protein (total N x 6.25) on a dry weight basis. The in vitro rumen digestibility of the 48-h fermentation product was 30%, compared to 24% for the alkali-treated but unfermented sawdust. Growth was independent of sawdust particle size in the range 40 to 100 mesh. Fermentation of the pretreatment liquor gave a product containing up to 50% crude protein (dry weight basis) with an in vitro rumen digestibility of 65 to 76%. Approximately 6.7 g of crude protein was obtained from the treated solids and 2.2 g from the pretreatment liquor per 100 g of sawdust treated. The product from the pretreatment liquor fermentation has potential as a high-protein animal feed supplement but could not be produced economically without an outlet for the re...

Biotechnology and Bioengineering, 2005

Many plant gums, such as gum arabic, contain hydroxyproline-rich glycoproteins (HRGPs), which are... more Many plant gums, such as gum arabic, contain hydroxyproline-rich glycoproteins (HRGPs), which are also abundant components of the plant cell extracellular matrix. Here we expressed in transgenic BY2