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1.
A Kalayanamitr A Bhumiratana T W Flegel T Glinsukon A Shinmyo 《Applied and environmental microbiology》1987,53(8):1980-1982
A soy sauce koji mold, Aspergillus flavus var. columnaris Raper and Fennel (ATCC 44310), was treated with UV irradiation to obtain mutant strains possessing high protease activities, high amylase activities, and light-colored conidia. Selected mutant strains were tested for toxicity, and some were found acutely toxic to weanling rats, although all were negative for aflatoxin production. 相似文献
2.
A number of strains of Bacillus popilliae were examined for their ability to oxidize acetate. Some of these would not sporulate in vitro, and some were oligosporogenous. The ability to oxidize acetate varied widely among the strains tested. A culture derived from spores of the parent strain produced in vivo and one of the asporogenous strains derived from it failed to produce any significant levels of (14)CO(2) from [(14)C]acetate. Oligosporogenous strains derived from the same parent culture all produced (14)CO(2) from both [1-(14)C] and [2-(14)C]acetate but at relatively low rates. The highest rates of acetate oxidation were observed with three strains which did not produce spores in vitro. When cultured under appropriate conditions, one of these strains displayed a secondary growth response concomitant with a decrease in the titratable acidity and an increase in the pH of the medium. The data indicate that B. popilliae has a complete citric acid cycle but that the activity of the cycle is strongly repressed in wild-type strains under the usual conditions used for in vitro cultivation. 相似文献
3.
Five different isolates of Aspergillus and one of Mucor were compared with a Japanese commercial strain of Aspergillus oryzae for proteolytic activity on wheat bran substrate. One isolate of Aspergillus with superior protease production, identified as Aspergillus flavus var. columnaris, showed no detectable aflatoxin production on glutinous rice or soybean substrate. Preliminary tests using this fungus as a koji mold in a traditionally operated factory resulted in a soy sauce superior in quality to that usually produced. 相似文献
4.
Paungmoung P Punya J Pongpattanakitshote S Jeamton W Vichisoonthonkul T Bhumiratana S Tanticharoen M Linne U Marahiel MA Cheevadhanarak S 《FEMS microbiology letters》2007,274(2):260-268
Nonribosomal peptides, synthesized by nonribosomal peptide synthetases (NRPS), are an important group of diverse bioactive fungal metabolites. Xylaria sp. BCC1067, which is known to produce a variety of biologically active metabolites, was studied for gene encoding NRPS by two different PCR-based methods and seven different NRPS fragments were obtained. In addition, screening a genomic library with an amplified NRPS fragment as a probe identified a putative NRPS gene named XyNRPSA. The functionality of XyNRPSA for the production of a corresponding metabolite was probed by gene insertion inactivation. Comparing the disrupting metabolite profile with that of the wild type led to the identification of a speculated metabolite. The crude extract of Xylaria sp. BCC1067 also exhibits antifungal activity against the human pathogens Candida albicans and Trichophyton mentagrophytes. However, the evaluation of biological activity of the XyNRPSA product suggests that it is neither a compound with antifungal activity nor a siderophore. In the vicinity of XyNRPSA, a second gene (named XyPtB) was identified. Its localization and homology to orfB of the ergot alkaloid biosynthetic gene cluster suggests that XyPtB may be involved in XyNRPSA product biosynthesis. 相似文献
5.
Chanpen Wiwat Watanalai Panbangred Amaret Bhumiratana 《Journal of industrial microbiology & biotechnology》1990,6(1):19-27
Summary The plasmids pBC16 and pC194 fromBacilus thuringiensis subsp.israelensis strains A084-16-194 were transferred to 25 subspecies ofB. thuringiensis by a conjugation-like process using broth mating technique. The frequencies of transfer varied considerably between different mating pairs, ranging from 1.1×10–9 to 9.8×10–5. Additionally, chromosomal transfer could also be demonstrated in tenB. thuringiensis subspecies with very low frequencies (4.3×10–9 to 3.7×10–7). The intersubspecies matings within a group of eight subspecies strains gave higher frequencies of transfer than the matings between the subspecies. Furthermore, the results indicated that the capability to transfer plasmids among these various subspecies did not depend on the presence of large plasmid. 相似文献
6.
Asawin?MeechaiEmail author Siriluk?Pongakarakun Patcharaporn?Deshnium Supapon?Cheevadhanarak Sakarindr?Bhumiratana 《Biotechnology and Bioprocess Engineering》2004,9(6):506-513
Spirulina produces γ-linolenic acid (GLA), an important pharmaceutical substance, in a relatively low level compared with fungi and
plants, prompting more research to improve its GLA yield. In this study, metabolic flux analysis was applied to determine
the cellular metabolic flux distributions in the GLA synthetic pathways of twoSpirulina strains, wild type BP and a high-GLA producing mutant Z19/2. Simplified pathways involving the GLA synthesis ofS. platensis formulated comprise of photosynthesis, gluconeogenesis, the pentose phosphate pathway, the anaplerotic pathway, the tricarboxylic
cycle, the GLA synthesis pathway, and the biomass synthesis pathway. A stoichiometric model reflecting these pathways contains
17 intermediates and 22 reactions. Three fluxes—the bicarbonate (C-source) uptake rate, the specific growth rate, and the
GLA synthesis rate—were measured and the remaining fluxes were calculated using linear optimization. The calculation showed
that the flux through the reaction converting acetyl-CoA into malonyl-CoA in the mutant strain was nearly three times higher
than that in the wild-type strain. This finding implies that this reaction is rate controlling. This suggestion was supported
by experiments, in which the stimulating factors for this reaction (NADPH and MgCl2) were added into the culture medium, resulting in an increased GLA-synthesis rate in the wild type strain. 相似文献
7.
Grayson WL Marolt D Bhumiratana S Fröhlich M Guo XE Vunjak-Novakovic G 《Biotechnology and bioengineering》2011,108(5):1159-1170
There is a critical need to increase the size of bone grafts that can be cultured in vitro for use in regenerative medicine. Perfusion bioreactors have been used to improve the nutrient and gas transfer capabilities and reduce the size limitations inherent to static culture, as well as to modulate cellular responses by hydrodynamic shear. Our aim was to understand the effects of medium flow velocity on cellular phenotype and the formation of bone‐like tissues in three‐dimensional engineered constructs. We utilized custom‐designed perfusion bioreactors to culture bone constructs for 5 weeks using a wide range of superficial flow velocities (80, 400, 800, 1,200, and 1,800 µm/s), corresponding to estimated initial shear stresses ranging from 0.6 to 20 mPa. Increasing the flow velocity significantly affected cell morphology, cell–cell interactions, matrix production and composition, and the expression of osteogenic genes. Within the range studied, the flow velocities ranging from 400 to 800 µm/s yielded the best overall osteogenic responses. Using mathematical models, we determined that even at the lowest flow velocity (80 µm/s) the oxygen provided was sufficient to maintain viability of the cells within the construct. Yet it was clear that this flow velocity did not adequately support the development of bone‐like tissue. The complexity of the cellular responses found at different flow velocities underscores the need to use a range of evaluation parameters to determine the quality of engineered bone. Bioeng. 2011; 108:1159–1170. © 2010 Wiley Periodicals, Inc. 相似文献
8.
Chanpen Wiwat Watanalai Panbangred Skorn Mongkolsuk Somsak Pantuwatana Amaret Bhumiratana 《Current microbiology》1995,30(2):69-75
Extraction of the S-layer protein by treatment with 6 m urea revealed a high-molecularweight protein in the extracts obtained from Bacillus thuringiensis subsp. israelensis (B.t.i) strain 4Q2. This protein band was found to be absent in partially cured (4Q2-72) and completely cured (c4Q2-72) strains. The antibody toward this S-layer protein was prepared and used to locate its antigenic protein on B.t.i cells by using indirect immunofluorescence. Immunodiffusion reactions and Western blot analysis confirmed the specificity of the anti-S-layer protein antibody. It was found that the antibody against 4Q2 S-layer protein, inhibited plasmid transfer via a conjugationlike process between, B.t.i. strains 4Q2-16 and c4Q2-72. That is, the frequency of transfer of plasmid pBC16 was reduced from 9.7×10-6 in the absence of the antibody to less than 1.0×10-8 in the presence of the antibody. The antibody was also found to reduce the frequency of pBC16 plasmid transfer via a conjugation-like process between B.t.i. strains A084-16-194 and c4Q2-72 from 2.2×10-5 in the absence of the antibody to 1.2×10-6 in the presence of the antibody. 相似文献
9.
Thailand is very much aware of the potential and the opportunities in biotechnology and has given the utmost effort into the development of biotechnology. In 1983, the government has set up the National Center for Genetic Engineering and Biotechnology (NCGEB). The center operates through a network of research institutes and laboratories in order to maximize and consolidate the limited resources of the country. The center also plays a key role in formulating policies and plans relating to biotechnology as well as in supporting and coordinating biotechnology research and development. A sum of U.S. $8.6 million has been allocated for an initial 5-year program for R D & E activities. The priority consideration is on utilizing various levels of biotechnology for improvement in agriculture, industrial productivity, health, and environment. To facilitate and strengthen the link between research institutions and the private sector, the high-level Science and Technology Development Board (STDB) was established in 1986, with an initial allocation of U.S. $2.9 million between 1986 to 1992 for biotechnology. At present, there are between 400 to 500 scientists and technologists with M.S. or higher degrees actively working in research and development (R & D) in biotechnology and engineering, mostly in universities and government research laboratories. It is expected that approximately 500 graduates with advanced degrees in biotechnology and related fields will be produced during the 5-year plan (1987 to 1991). 相似文献
10.