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991.
Light-activated cytotoxic compounds from Malaysian microorganisms for photodynamic therapy of cancer
Nurkhalida Kamal Vikineswary Sabaratnam Noorlidah Abdullah Anthony S. H. Ho Soo H. Teo Hong B. Lee 《Antonie van Leeuwenhoek》2009,95(2):179-188
Photodynamic therapy (PDT) is a promising cancer treatment which involves activation of a photosensitizing drug with light to produce reactive oxygen species that kill tumors without causing damage to unirradiated normal tissues. To date, only Photofrin®, Foscan® and Levulan® have been approved for clinical treatment of cancer. Tropical habitats such as those found in Malaysia are attractive sources of new therapeutic compounds as tremendous chemical diversity is found in a large number of plants, animals, marine- and micro-organisms. In our screening program for novel photosensitizers from nature, colorful strains of fungi (from Aspergillus and Penicillium genus) and bacteria (including actinomycetes and photosynthetic bacteria) were collected from various habitats in Peninsular Malaysia, such as coastal soil, peat soil, marine sponges and wastewater ponds. Methanolic extracts from a total of 85 different species were evaluated with a short-term cell viability assay for photo-cytotoxicity, where a promyelocytic leukemia cell-line, HL60 incubated with 20 μg/ml of extracts was irradiated with 9.6 J/cm2 of a broad spectrum light. Two of these extracts, one from Rhodobacter sphaeroides (PBUM003) and one from Rhodopseudomonas palustris (PBUM001) showed moderate to strong photo-cytotoxicity. Subsequent bioassay guided isolation of the PBUM001 extract yielded known photosensitisers that are based on bacteriochlorophyll-a by comparing their molecular weight data, HPLC profiles and UV–vis absorption spectra with literature values, thereby demonstrating the validity of our screening approach. 相似文献
992.
A single chamber stackable microbial fuel cell (SCS-MFC) comprising four MFC units was developed. When operated separately,
each unit generated a volumetric power density (Pmax,V) of 26.2 W/m3 at 5.8 mA or 475 mV. The total columbic efficiency was 40% for each unit. Parallel connection of four units produced the
same level of power output (Pmax,V of 22.8 W/m3 at 27 mA), which was approximately four times higher than a single unit alone. Series connection of four units, however,
only generated a maximum power output of 14.7 W/m3 at 730 mV, which was less than the expected value. This energy loss appeared to be caused by lateral current flow between
two units, particularly in the middle of the system. The cathode was found to be the major limiting factor in our system.
Compared to the stacked operation of multiple separate MFCs, our single chamber reactor does not require a delicate water
distribution system and thus is more easily implemented in pre-existing wastewater treatment facilities with serpentine flow
paths, such as fixed-bed reactors, with minimal infrastructure changes. 相似文献
993.
Thermotolerant and thermostable laccases 总被引:1,自引:0,他引:1
Laccases are phenol-oxidizing, usually four-copper containing metalloenzymes. For industrial and biotechnological purposes,
laccases were among the first fungal oxidoreductases providing larger-scale applications such as removal of polyphenols in
wine and beverages, conversion of toxic compounds and textile dyes in waste waters, and in bleaching and removal of lignin
from wood and non-wood fibres. In order to facilitate novel and more efficient bio-catalytic process applications, there is
a need for laccases with improved biochemical properties, such as thermostability and thermotolerance. This review gives a
current overview on the sources and characteristics of such laccases, with particular emphasis on the fungal enzymes. 相似文献
994.
A strain Aureobasidium pullulans AP329, was used for the production of pullulan by employing hydrolysed sweet potato as cultivation media. Hydrolysis with α-amylase alone resulted in the lowest yields of pullulan. In contrast continuous hydrolysis with pullulanase and the β-amylase in sweet potato itself gave higher yields, but prolonged hydrolysis with amyloglucosidase decreased the yield. The maximum pullulan yield (29.43 g/l) was achieved at the dextrose equivalent value of 45 and pH of 5.5 for 96 h. As a substitute of sucrose, hydrolysed sweet potato was found to be hopeful and the yield of pullulan was higher than that of glucose and sucrose. The molecular weight of pullulan obtained from hydrolysed sweet potato media was much higher than that of sucrose and glucose media. Results of this work indicated that sweet potato was a promising substrate for the economical production of pullulan. 相似文献
995.
Bo-Hon Chou Shwu-Fen Chang Chia-Hsin Lo Wen-Kuang Lin Pan-Chun Liu 《Phytochemistry》2009,70(6):759-1385
A number of hydroxylated diterpenoids were obtained from the microbial transformation of isosteviol lactone (4α-carboxy-13α-hydroxy-13,16-seco-ent-19-norbeyeran-16-oic acid 13,16-lactone) (2) with Mucorrecurvatus MR 36, Aspergillusniger BCRC 31130, and Absidiapseudocylindrospora ATCC 24169. Incubation of 2 with M. recurvatus and Asp.niger led to isolation of seven known compounds (1 and 3-8). Incubation of 2 with Abs. pseudocylindrospora produced 5 and six previously unreported compounds (9-14). The structures of these isolated compounds were deduced by high-field NMR techniques (1H, 13C, DEPT, COSY, NOESY, HSQC, and HMBC), and those of 9 and 11 were further confirmed by X-ray crystallographic analyses. Subsequently, the inhibitory effects on activator protein-1 (AP-1) activation in lipopolysaccharide-stimulated RAW 264.7 macrophages of all of these compounds were evaluated. Compounds 2-5, 8, 9, 11, and 12 exhibited significant inhibitory activity, while 3 was more potent than the reference compound of dexamethasone. 相似文献
996.
D. R. Bowling W. J. Massman S. M. Schaeffer S. P. Burns R. K. Monson M. W. Williams 《Biogeochemistry》2009,95(1):37-59
Considerable research has recently been devoted to understanding biogeochemical processes under winter snow cover, leading
to enhanced appreciation of the importance of many winter ecological processes. In this study, a comprehensive investigation
of the stable carbon isotope composition (δ13C) of CO2 within a high-elevation subalpine forest snowpack was conducted. Our goals were to study the δ13C of biological soil respiration under snow in winter, and to assess the relative importance of diffusion and advection (ventilation
by wind) for gas transport within snow. In agreement with other studies, we found evidence of an active microbial community
under a roughly 1-m deep snowpack during winter and into spring as it melted. Under-snow CO2 mole fractions were observed up to 3,500 μmol mol−1, and δ13C of CO2 varied from ~−22 to ~−8‰. The δ13C of soil respiration calculated from mixing relationships was −26 to −24‰, and although it varied in time, it was generally
close to that of the bulk organic horizon (−26.0‰). Subnivean CO2 and δ13C were quite dynamic in response to changes in soil temperature, liquid water availability, and wind events. No clear biologically-induced
isotopic changes were observed during periods when microbial activity and root/rhizosphere activity were expected to vary,
although such changes cannot be eliminated. There was clear evidence of isotopic enrichment associated with diffusive transport
as predicted by theory, but simple diffusive enrichment (4.4‰) was not observed. Instead, ventilation of the snowpack by sustained
wind events in the forest canopy led to changes in the diffusively-enriched gas profile. The isotopic influence of diffusion
on gases in the snowpack and litter was greatest at greater depths, due to the decreased relative contribution of advection
at depth. There were highly significant correlations between the apparent isotopic content of respiration from the soil with
wind speed and pressure. In summary, physical factors influencing gas transport substantially modified and potentially obscured
biological factors in their effects on δ13C of CO2 within this subalpine forest snowpack. 相似文献
997.
Teresa De Diego Pedro Lozano Miguel A. Abad Katharina Steffensky Michel Vaultier Jos L. Iborra 《Journal of biotechnology》2009,140(3-4):234-241
Free and immobilized lipases from Candida antarctica (CALA and CALB), Thermomyces lanuginosus (TLL) and Rhizomucor miehei (RML) were used as catalysts in the synthesis of butyl propionate by transesterification in reaction media consisting in nine different ionic liquids. Enzyme activities were clearly dependent on the nature of the ions, the results being improving as the alkyl chain length of the imidazolium cation increased, and as a function of the type of anion ([PF6], [BF4] or [ethylsulphate]). The best synthetic activity (655.5 U/mg protein at 40 °C) was obtained when free CALB were assayed in the water-miscible IL cocosalkyl pentaethoxy methyl ammonium methosulfate ([CPMA][MS]), and was clearly related with the water content of the medium. The synthetic activity of free CALB in [CPMA][MS] was enhanced with the increase in temperature, while practically no effect was obtained for TLL. The ability of free CALB to synthesize aliphatic esters of different alkyl chain lengths, using different alkyl vinyl esters and 1-alkanols as substrates, was also studied in [CPMA][MS], the best results (4500 U/mg protein) being obtained for the synthesis of hexyl butyrate. 相似文献
998.
Ravita TD Tanner RS Ahearn DG Arms EL Crockett PW 《Journal of industrial microbiology & biotechnology》2009,36(1):35-38
Ninety-six used personal care and topical OTC drug items collected from consumers in the USA were examined for the presence of microbial contaminants. Of the eye and face product type containing global preservative chemistries (i.e., acceptable for use in Japan without major restrictions), 55% yielded numbers of microorganisms in excess of 500 CFU/g (P < 0.1814). For the mascara products with global preservative chemistries, 79% yielded numbers of microorganisms in excess of 500 CFU/g (P < 0.024). Products containing global preservative chemistries accounted for 88% (n = 14) of the products that had microbial contents above 10(4) CFU/g (P < 0.001). Prominent contaminants were species of Staphylococcus, Pseudomonas, Klebsiella, Streptococcus, Lactobacillus, Bacillus, Corynebacterium, and yeast. In general, under the stress of consumer use, products preserved with global preservative chemistries did not maintain as adequate preservation as products with non-global preservatives. 相似文献
999.
Ryuji Kondo Akie Nakagawa Lisa Mochizuki Kyoko Osawa Yukiyasu Fujioka Junki Butani 《Limnology》2009,10(1):63-69
Lake Suigetsu is a typical meromictic lake in Japan characterized by a permanent chemocline at a depth of between 3 and 8 m
separating the oxic freshwater mixolimnion from anoxic saline sulfidogenic monimolimnion. Dominant bacterioplankton populations
in Lake Suigetsu were investigated using PCR-denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. The
bacterial population was vertically stratified, and temporal shifts in the microbial communities were observed in both the
oxic and anoxic layers of Lake Suigetsu during the sampling period. Several dominant DGGE bands were excised and sequenced.
In the chemocline, green sulfur bacteria phylogenetically related to the genera Prosthecochloris, Pelodyctyon, and Chlorobium within the phylum Chlorobi were dominant; the colorless sulfur bacteria closely related to the genus Thiomicrospira were detected. These sulfur bacterial groups appear to be important in the biogeochemical cycling of sulfur and/or carbon
in Lake Suigetsu. Bacterial sequences affiliated with the Bacteroidetes phylum were frequent among the dominant fragments in the DGGE profiles throughout the water column. Populations possessing
a fermentative metabolism exist in Bacteroidetes, suggesting they may contribute to the degradation of organic matter in the anoxic environment of Lake Suigetsu. 相似文献
1000.
Question: How do N fertilization and disturbance affect the understorey vegetation, microbial properties and soil nutrient concentration in boreal forests? Location: Kuusamo (66°22′N; 29°18′E) and Oulu (65°02′N; 25°47′E) in northern Finland. Methods: We conducted a fully factorial experiment with three factors: site (two levels), N fertilization (four levels) and disturbance (two levels). We measured treatment effects on understorey biomass, vegetation structure, and plant, soil and microbial N and C concentrations. Results: The understorey biomass was not affected by fertilization either in the control or in the disturbance treatment. Fertilization reduced the biomass of deciduous Vaccinium myrtillus. Disturbance had a negative effect on the biomass of V. myrtillus and evergreen Vaccinium vitis‐idaea and decreased the relative proportion of evergreen species. Fertilization and disturbance increased the biomass of grass Deschampsia flexuosa and the relative proportion of graminoids. The amount of NH4+ increased in soil after fertilization, and microbial C decreased after disturbance. Conclusions: Our results suggest that the growth of slow‐growing Vaccinium species and soil microbes in boreal forests are not limited by N availability. However, significant changes in the proportion of dwarf shrubs to graminoids and a decrease in the biomass of V. myrtillus demonstrate the susceptibility of understorey vegetation to N enrichment. N enrichment and disturbance seem to have similar effects on understorey vegetation. Consequently, increasing N does not affect the rate or the direction of recovery after disturbance. Moreover, our study demonstrates the importance of understorey vegetation as a C source for soil microbes in boreal forests. 相似文献