Effects of vegetation type on microbial biomass carbon and nitrogen in subalpine mountain forest soils.

BACKGROUND/PURPOSE: Microbial biomass plays an important role in nutrient transformation and conservation of forest and grassland ecosystems. The objective of this study was to determine the microbial biomass among three vegetation types in subalpine mountain forest soils of Taiwan. METHODS: Tatachia is a typical high-altitude subalpine temperate forest ecosystem in Taiwan with an elevation of 1800-3952 m and consists of three vegetation types: spruce, hemlock, and grassland. Three plots were selected in each vegetation type. Soil samples were collected from the organic layer, topsoil, and subsoil. Microbial biomass carbon (Cmic) was determined by the chloroform fumigation-extraction method, and microbial biomass nitrogen (Nmic) was determined from the total nitrogen (Ntot) released during fumigation-extraction. Bacteria, actinomycetes, fungi, cellulolytic microbes, phosphate-solubilizing microbes, and nitrogen-fixing microbes were also counted. RESULTS: The Cmic and Nmic were highest in the surface soil and declined with the soil depth. These were also highest in spruce soils, followed by in hemlock soils, and were lowest in grassland soils. Cmic and Nmic had the highest values in the spring season and the lowest values in the winter season. Cmic and Nmic had significantly positive correlations with total organic carbon (Corg) and Ntot. Contributions of Cmic and Nmic, respectively, to Corg and Ntot indicated that the microbial biomass was immobilized more in spruce and hemlock soils than in grassland soils. Microbial populations of the tested vegetation types decreased with increasing soil depth. CONCLUSION: Cmic and Nmic were high in the organic layer and decreased with the depth of layers. These values were higher for spruce and hemlock soils than for grassland soils. Positive correlations were observed between Cmic and Nmic and between Corg and Ntot.

Protein enrichment and digestion improvement of napiergrass and pangolagrass with solid-state fermentation.

BACKGROUND AND PURPOSE: Napiergrass (Pennisetum purpureum Schumacher) and pangolagrass (Digitaria decumbens Stent) are two major forage grasses for cow feeding. They possess high yields and high regeneration properties. Inoculation of cellulolytic microbes on herbage could enhance the protein content of herbage and promote digestibility in chickens. METHODS: Cellulolytic microbes were isolated from various sources and cultivated on napiergrass and pangolagrass with solid-state fermentation for protein enrichment and in vitro digestion improvement.The fermented napiergrass and pangolagrass were used as the main protein source in chicken diets to assess the feasibility for non-ruminants feed. RESULTS: After a 42-day fermentation period, napiergrass showed higher protein contents (13.4-13.9%) than those of pangolagrass(11.1-11.7%). The in vitro digestibility of pangolagrass increased from 5.29% to 20.4%, whereas that of napiergrass increased from 5.29% to 19.0%. The average feed conversion efficiencies of chickens were close to the traditional fodder using corn as the main ingredient. CONCLUSION: Inoculation of appropriate cellulolytic microbes to enrich protein content and improve in vitro digestibility of herbage with solid-state fermentation for chicken feed is the prospective technique for agriculture, animal husbandry, and substantial management.

Protein enrichment, cellulase production and in vitro digestion improvement of pangolagrass with solid state fermentation.

BACKGROUND AND PURPOSE: Pangolagrass, Digitaria decumbens Stent, is a major grass for cow feeding, and may be a good substrate for protein enrichment. To improve the quality of pangolagrass for animal feeding, cellulolytic microbes were isolated from various sources and cultivated with solid state fermentation to enhance the protein content, cellulase production and in vitro digestion. The microbes, culture conditions and culture media were studied. METHODS: Cellulolytic microbes were isolated from pangolagrass and its extracts, and composts. Pangolagrass supplemented with nitrogen and minerals was used to cultivate the cellulolytic microbes with solid state fermentation. The optimal conditions for protein enrichment and cellulase activity were pangolagrass substrate at initial moisture 65-70%, initial pH 6.0-8.0, supplementation with 2.5% (NH(4))(2)SO(4), 2.5% KH(2)PO(4) and K(2)HPO(4) mixture (2:1, w/w) and 0.3% MgSO(4).7H(2)O and cultivated at 30(o)C for 6 days. RESULTS: The protein content of fermented pangolagrass increased from 5.97-6.28% to 7.09-16.96% and the in vitro digestion improved from 4.11-4.38% to 6.08-19.89% with the inoculation of cellulolytic microbes by solid state fermentation. Each 1 g of dried substrate yielded Avicelase 0.93-3.76 U, carboxymethylcellulase 1.39-4.98 U and ß-glucosidase 1.20-6.01 U. The isolate Myceliophthora lutea CL3 was the strain found to be the best at improving the quality of pangolagrass for animal feeding with solid state fermentation. CONCLUSION: Solid state fermentation of pangolagrass inoculated with appropriate microbes is a feasible process to enrich protein content, increase in vitro digestibility and improve the quality for animal feeding.

Microbial communities and bacterial diversity of spruce, hemlock and grassland soils of Tatachia Forest, Taiwan.

To evaluate the bacterial diversity of Tatachia Forest soils, 16S rDNA clone libraries of the spruce, hemlock and grassland soils were constructed. Further, the influence of physicochemical and biological properties of soil on microbial ecology, pH, moisture content, microbial population and biomass were also analyzed. The soil pH increased with the increasing of soil depth; whereas the microbial population, biomass, moisture content, total organic carbon and total nitrogen were reverse. Microbial populations were the highest in the summer season which also correlated with the highest moisture content. The phylogenetic analyses revealed that the clones from nine 16S rDNA clone libraries represented Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Gemmatimonadetes, Planctomycetes, Verrucomicrobia, candidate division TG1 and candidate division TM7. Members of Proteobacteria, Acidobacteria and Actinobacteria constituted 42.2, 35.1 and 7.8 % of the clone libraries, respectively; whereas the remaining bacterial divisions each comprised <3 %. The spruce site had the highest bacterial diversity among the tested sites, followed by the hemlock sites and the grassland sites with the least. The bacterial community is the more diverse in the organic layer than that in deeper horizons. Further, bacterial diversity through the gradient horizons was different, indicating that the bacterial diversity in the deeper horizons is not simply the diluted analogs of the surface soils and some microbes dominate only in the deeper horizons.

Inoculation of food waste with the thermo-tolerant lipolytic actinomycete Thermoactinomyces vulgaris A31 and maturity evaluation of the compost.

The ability of the thermo-tolerant lipolytic actinomycete, Thermoactinomyces vulgaris A31, to efficiently decompose food waste into mature compost was studied. Using a range of chemical parameters (pH, total organic carbon content (TOC), total nitrogen content, C/N ratio), CO(2) evolution, enzymatic activities (dehydrogenase, polyphenol oxidase, urease) and germination assays, the composition, stability and maturity of the compost produced were assessed. Inoculation reduced crude fat and decreased the maturation time of the compost when compared with the control. TOC, C/N ratio, CO(2) evolution, and enzymatic activities (dehydrogenase, polyphenol oxidase, urease) decreased, pH, total nitrogen content, germination rate, and germination index increased. The dehydrogenase, polyphenol oxidase, and urease activities were shown to be useful indicators for the stability of food waste composts. Based on germination assays, the food waste composts were phytotoxicity free and matured after composting for 2 months. Therefore, inoculation of food waste with the thermo-tolerant lipolytic actinomycete, T. vulgaris A31, presents as a feasible strategy to convert food wastes into mature compost efficiently.

Thermo-tolerant phosphate-solubilizing microbes for multi-functional biofertilizer preparation.

In order to prepare the multi-functional biofertilizer, thermo-tolerant phosphate-solubilizing microbes including bacteria, actinomycetes, and fungi were isolated from different compost plants and biofertilizers. Except Streptomycesthermophilus J57 which lacked pectinase, all isolates possessed amylase, CMCase, chitinase, pectinase, protease, lipase, and nitrogenase activities. All isolates could solubilize calcium phosphate and Israel rock phosphate; various isolates could solubilize aluminum phosphate, iron phosphate, and hydroxyapatite. During composting, biofertilizers inoculated with the tested microbes had a significantly higher temperature, ash content, pH, total nitrogen, soluble phosphorus content, and germination rate than non-inoculated biofertilizer; total organic carbon and carbon-to-nitrogen ratio showed the opposite pattern. Adding these microbes can shorten the period of maturity, improve the quality, increase the soluble phosphorus content, and enhance the populations of phosphate-solubilizing and proteolytic microbes in biofertilizers. Therefore, inoculating thermo-tolerant phosphate-solubilizing microbes into agricultural and animal wastes represents a practical strategy for preparing multi-functional biofertilizer.

The identification, purification, and characterization of STXF10 expressed in Streptomyces thermonitrificans NTU-88.

Multiple xylanolytic enzymes of Streptomyces thermonitrificans NTU-88 were induced by oat-spelt xylan and separated by two-dimensional polyacrylamide and zymogram gels. Nineteen clear spots differed in pI and molecular weight values were found on the zymogram, and only spot one was seen on the corresponding silver-stained gel. These results revealed that multiple xylanases were secreted when S. thermonitrificans NTU-88 was induced and the spot (STXF10), identified as being a glycosyl hydrolase family 10 xylanase, was the predominant one among xylanases. STXF10 showed a tolerance for high temperatures and broad pH ranges and high affinity and hydrolysis efficiency for xylans. Furthermore, it also featured the minor ability to degrade different lignocellulosic substrates. Although S. thermonitrificans NTU-88 possesses multiple xylanases, our results suggest that the major form of xylanase might be selectively and specifically induced depending on the type of substrate to which the microorganism is exposed.

Multiplex PCR detection of enterotoxin genes in Aeromonas spp. from suspect food samples in northern Taiwan.

Aeromonads possess an array of virulence factors and are causative agents of a number of human infections. Among them, genes of one cytotoxic (Act) and two cytotonic (Alt, Ast) enterotoxins are implicated in a human diarrheal disease. A rapid, specific, simultaneous detection of these enterotoxin genes in suspected food poisoning samples is not yet reported. Hence, a multiplex PCR assay was designed to amplify the cytotoxic (act), heat-labile cytotonic (alt), and heat-stable cytotonic (ast) enterotoxin genes of aeromonads. The PCR assay was tested with 133 Aeromonas spp. isolated from suspect food poisoning samples and retail samples of poultry and fish from wet markets in and around Taipei, Northern Taiwan. The Aeromonas spp. isolates were divided into six genotypes based on absence or presence of one or more enterotoxin genes. Of these 133 isolates, Aeromonas caviae (52.5%) and Aeromonas hydrophila (43.4%) were the most frequently isolated species from food poisoning samples and retail samples, respectively. Among the species, A. hydrophila had a significantly higher proportion for harboring three enterotoxin genes than had the others, whereas Aeromonas encheleia, considered a nonpathogen, was found harboring three enterotoxin genes. The multiplex PCR assays are rapid and specific, and provide a useful tool for the detection and genotyping of enterotoxin genes of aeromonads.

Polyunsaturated fatty acids production with a solid-state column reactor.

To investigate the potential production of polyunsaturated fatty acids (PUFAs), a solid-state column reactor of rice bran with Mortierella alpina was used. The optimal conditions for PUFAs production were rice bran supplementation with 3.75% (ww(-1)) nitrogen source at initial moisture content 57%, initial pH 6-7, aeration, and incubation at 20 degrees C for 5 days and then at 12 degrees C for 7 days. Each gram of substrate carbon yielded 127 mg of total PUFAs, 12 mg of eicosapentaenoic acid (EPA), 6 mg of arachidonic acid (AA), 5mg of alpha-linolenic acid (ALA), and 117 mg of linoleic acid (LA) after 12 days incubation. Aeration enhanced the productions of AA, EPA, and total PUFAs. Supplementation of the nitrogen source on the fourth day and then a shift to lower temperature on the fifth day increased EPA production.

Methane and carbon dioxide emissions from closed landfill in Taiwan.

The atmospheric concentrations and emission rates of CH(4) and CO(2) were studied at three sites of the Fu-Der-Kan closed landfill and after as the multi-use recreational park in northern Taiwan. Atmospheric CH(4) and CO(2) concentrations of closed landfill were 1.7-4.6 and 324-409ppm, respectively. CH(4) and CO(2) emission rates ranged from 8.8 to 163mg m(-2)h(-1) and from 495 to 1531mg m(-2)h(-1), respectively. Diurnal variation was noted with higher values at night than those in daytime. After creation of the park, atmospheric CH(4) and CO(2) concentrations were 1.8-3.1 and 332-441ppm, respectively. CH(4) and CO(2) emission rates ranged from -1.1 to 2.3mg m(-2)h(-1) and from -135 to 301mg m(-2)h(-1), respectively. There were no notable diurnal variations in either atmospheric concentrations or emission rates.

Seasonal variation of microbial populations and biomass in Tatachia grassland soils of Taiwan.

To investigate the seasonal variations of microbial ecology in grassland of Tatachia forest, soil properties, microbial populations, microbial biomass, and 16S rDNA clone library analysis were determined. The soil had temperatures 6.6-18.4 degrees C, pH 3.6-5.1, total organic carbon 1.11-10.68%, total nitrogen 0.18-0.78%, and C/N ratios 3.46-20.55. Each gram of dry soil contained bacteria, actinomycetes, fungi, cellulolytic, phosphate-solubilizing microbes, and nitrogen-fixing microbes 4.54 x 10(4) to 3.79 x 10(7), 3.43 x 10(2) to 2.17 x 10(5), 5.74 x 10(3) to 3.76 x 10(6), 1.97 x 10(3) to 1.34 x 10(6), 8.49 x 10(2) to 5.59 x 10(5), and 3.86 x 10(2) to 3.75 x 10(5) CFU, respectively. Each gram of soil contained 117-2,482 microg of microbial biomass carbon, 23-216 microg of microbial biomass nitrogen and 9-29 microg of DNA. The microbial populations, microbial biomass, and DNA decreased stepwise with the depth of soil, and they had low values in winter seasons. The microbial populations, microbial biomass carbon, microbial biomass nitrogen, and DNA at the BW2 horizon were 8.42-17.84, 19.26-64.40, 16.84-61.11, and 31.03-46.26% of those at the O horizon, respectively. When analyzing 16S rDNA library, members of Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, candidate division TMI, candidate division TM7, Gammatimonadetes, and Verrucomicrobia were identified. Members of Proteobacteria (44.4%) and Acidobacteria (33.3%) dominated the clone libraries. Within the phylum Proteobacteria, alpha-, beta-, and gamma-Proteobacteria were most numerous, followed by delta-Proteobacteria.

Cloning, characterization and phylogenetic relationships of stxI, a endoxylanase-encoding gene from Streptomyces thermonitrificans NTU-88.

A thermostable xylanase gene (stxI) obtained from Streptomyces thermonitrificans NTU-88 on domain analysis revealed an N-terminal catalytic domain featuring homology to a known xylanase within the glycoside hydrolase family 11. Recombinant STXI retained more than 60% of its activity following its incubation for at 60 degrees C for 24h. These characteristics were close to thermophile and mesophile Streptomyces strains. The main hydrolysis products of xylan degraded by STXI included large xylooligosaccharide fragments. These results indicated that STXI was a typical endoxylanase. As regards the phylogenetic relationships of GH11, STXI and the other xylanase deriving from Streptomyces were included in a subgroup of the aerobic bacterial group. This result implied that the evolutionary relationships between the various xylanases deriving from Streptomyces strains were convergent.

Application of thermotolerant microorganisms for biofertilizer preparation.

BACKGROUND AND PURPOSE: Intensive agriculture is practised in Taiwan, and compost application is very popular as a means of improving the soil physical properties and supplying plant nutrition. We tested the potential of inoculation with thermotolerant microorganisms to shorten the maturity and improve the quality of biofertilizer prepared by composting. METHODS: Thermotolerant microorganisms were isolated from compost and reinoculated for the preparation of biofertilizer. The physical, chemical and biological properties of the biofertilizer were determined during composting. The effects of biofertilizer application on the growth and yield of rape were also studied. RESULTS: Among 3823 colonies of thermotolerant microorganisms, Streptomyces thermonitrificans NTU-88, Streptococcus sp. NTU-130 and Aspergillus fumigatus NTU-132 exhibited high growth rates and cellulolytic and proteolytic activities. When a mixture of rice straw and swine manure were inoculated with these isolates and composted for 61 days, substrate temperature increased initially and then decreased gradually during composting. Substrate pH increased from 7.3 to 8.5. Microbial inoculation enhanced the rate of maturity, and increased the content of ash and total and immobilized nitrogen, improved the germination rate of alfalfa seed, and decreased the content of total organic carbon and the carbon/nitrogen ratio. Biofertilizer application increased the growth and yield of rape. CONCLUSIONS: Inoculation of thermotolerant and thermophilic microorganisms to agricultural waste for biofertilizer preparation enhances the rate of maturity and improves the quality of the resulting biofertilizer. Inoculation of appropriate microorganisms in biofertilizer preparation might be usefully applied to agricultural situations.

Molecular characterization of class 1 integrons and antimicrobial resistance in Aeromonas strains from foodborne outbreak-suspect samples and environmental sources in Taiwan.

One hundred thirty-three Aeromonas spp. isolates were examined for multiple antibiotic resistance phenotypes and prevalence of class 1 integron sequences. Twenty-four (18.0%) of these isolates contained class 1 integron. Seven different class 1 integrons were found among 24strains, with a total of 10 different gene cassettes encoding for resistance to trimethoprim (dfr12 and dfr2d), aminoglycosides (aadA1 and aadA2), beta-lactam antibiotics (oxa2), chloramphenicol (catB3 and catB8), quaternary ammonium amines (qacE2), and 2 ORFs (orfD and orfF) with unknown function. Rate of antibiotic resistance was different between integron-positive and integron-negative strains. Trimethoprim and trimethoprim-sulphamethoxazole resistances were commonly associated with integron, and all of integron-positive isolates were multiple resistant to more than 3 agents. Resistance to as many as 10 antimicrobial agents were observed in integron-positive strains. Several cassette arrays of class 1 integrons identified in this study were not previously reported in Aeromonas strains. This study demonstrates the wide distribution of class 1 integron in Aeromonas spp. isolated from foodborne outbreak-suspect samples and environmental sources in Taiwan.

Relationship between carbon dioxide/methane emissions and the water quality/sediment characteristics of Taiwan's main rivers.

River and sediment have unique carbon dynamics and are important sources of the dominant greenhouse gases (GHG), carbon dioxide (CO2) and methane (CH4). To understand the relationship between CO2/CH4 emissions and water quality/sediment characteristics, we have investigated critical parameters in the river water. Eight parameters of water quality (dissolved oxygen, oxidation-reduction potential [ORP], chemical oxygen demand, biochemical oxygen demand [BOD5], suspended solid, nitrate [NO3-], NH4+, and bacteria) and four sediment characteristics (total organic carbon [TOC], total nitrogen [T-N], NO3-, and ammonium [NH4+]) were measured in two of the larger rivers in Taiwan, and relevant environmental conditions were recorded. The experimental results indicated that CO2 emissions from the river were mainly affected by BOD5 concentrations and the levels of bacteria. CH4 emissions, on the other hand, were greatly affected by the ORP in the river. The correlation between CO2 emissions and sediment characteristics was insignificant (R2 < 0.3). However, TOC and T-N in the sediment may lead to increases in CH4 emissions into the atmosphere. A deeper analysis of the relationship between the different parameters and GHG emissions by ANOVA and the multiple regression method revealed that CO2 emission (y) was significantly related to bacteria number (x1) and BOD concentration (X2). The regression equation takes the form y = 0.00032x1 + 3.18089x2 + 25.37304. Also, the regression relationship between CH4 emission (y) and ORP (x) in the river can be described as y = -0.825216x + 169.02257. The relationship between CH4 emission and sediment characteristics may be described as y = 5.073962x1(TOC) + 2.871245x2(T-N) - 12.3262. Extra sampling data were collected to examine the feasibility of the developed multiple regression equations. The experimental results suggest that the emissions of such GHGs as CO2 and CH4 from rivers can be predicted using the regression equations developed here. Moreover, the emissions may be reduced by manipulating the proper factors.

Seasonal variation of microbial ecology in hemlock soil of Tatachia Mountain, Taiwan.

BACKGROUND AND PURPOSE: Forest soil microorganisms and fauna decompose the organic materials, and thus strongly influence the nutrient cycling of the ecosystem. Soil microorganisms also contribute to soil structure and soil fertility. In Taiwan, the microbial distributions of soils have only been determined in acidic soil, inorganic acidic soil, upland soil, alkaline soil and power plant areas. There are few data on the microbial populations of forest soils. Tatachia Mountain is located in the central part of Taiwan and is a typical high altitude protected ecosystem area, designated as a National Park. This study investigated the role of microorganisms in the ecology and nutrient transformation of forest soil in Taiwan. METHODS: As part of long-term ecological research in Taiwan, the environmental conditions, seasons, microbial populations, biomass and organic acid contents of hemlock soil were investigated. We also studied the effect of depth on microbial populations and biomass. RESULTS: The soil temperatures were between 5.5 and 15.6 degrees C and the soil pH ranged from 3.3 to 4.4. Total organic carbon and total nitrogen contents ranged from 2.3 to 37.1% and from 0.3 to 1.7%, respectively. The carbon/nitrogen ratio was between 8.2 and 24.4. In topsoil, each gram of soil contained 10(5)-10(7) colony-forming units (CFU) culturable bacteria, 10(2)-10(5) CFU actinomycetes, 10(3)-10(5) CFU fungi, 10(4)-10(6) CFU cellulolytic microbes, 10(4)-10(6) CFU phosphate-solubilizing microbes, and 10(3)-10(6) CFU nitrogen-fixing microbes. Microbial populations were higher in topsoil compared with subsoil, but lower in topsoil than in organic layer. Microbial populations also decreased with the depth of soil. Microbial populations at 1E horizon were 0.6% to 9.4% of those at O horizon. The microbial biomass evaluated contained carbon 391-1013 mug, nitrogen 51-146 mug, malic acid 76-557 nM and succinic acid 37-527 nM per gram of soil. Summer season had higher microbial populations, biomass and organic content than winter season, but the differences were not significant. CONCLUSION: Heavy coverage of organic matter was found in hemlock and spruce soils and was associated with acidic pH. Microbial populations decreased with increasing soil depth. Microbes play a very important role in organic matter decomposition and nutrition transformation in hemlock soil.

Mycelium and polysaccharide production of Agaricus blazei Murrill by submerged fermentation.

BACKGROUND AND PURPOSE: Over the last decade, Agaricus blazei Murrill has been studied and developed as a novel functional food in Japan, Korea, China, and Taiwan. Due to the low yields, the fruiting bodies of A. blazei Murrill are relatively expensive, and a cheap and stable source of A. blazei Murrill mycelium for commercial purposes is highly desirable. Culture media and conditions were investigated with a view to reducing the cost and improving the mycelium and polysaccharide production of A. blazei Murrill by submerged fermentation. METHODS: Thirty six isolates of A. blazei Murrill were isolated from 22 fruiting bodies produced in Taiwan, and 16 of them could be successfully cultivated on mannitol-egg yolk-polymyxin medium. The isolates were identified by species-specific polymerase chain reaction (PCR) and optimized for the culture media and conditions by submerged fermentation for mycelium and polysaccharide production. Some properties of polysaccharide extract were also investigated. RESULTS: All of the PCR products with species-specific primers showed high identity and matched the internal transcribed spacer 1 sequences of A. blazei Murrill. The phylogenic tree of A. blazei Murrill isolates generated from random amplified polymorphic DNAs arranged all samples into 3 groups and 2 independent cases. The optimal culture media of mycelium production in submerged fermentation were 5% malt extract, 0.1% yeast extract, and 0.5% peptone at pH 6.0, while the optimal culture conditions were 200 mL medium in 500 mL Hinton flask, shaking at 90 rpm for 3 days and then shifting to 105 rpm for 5 days at 27 degrees C. Each liter of A. blazei Murrill M72 yielded 10.83 +/- 0.24 g dried mycelia weight and each liter of A. blazei Murrill M152 produced 0.251 +/- 0.004 g crude polysaccharide (3.03 +/- 0.05% of dried mycelia weight). Crude polysaccharide of A. blazei Murrill M162 contained 82.27-99.14% of total sugar and less than 1.63% of protein; it had 4 major molecular weight components (274.1, 32.7, 7.5, and 2.1 kDa, respectively), with the 2.1 kDa portion possibly a beta-(1,3)-glucan. CONCLUSIONS: These results show that selection of media and conditions can be employed in order to improve the mycelium and polysaccharide production of A. blazei Murrill M72 or M152 by submerged fermentation. Mycelia and polysaccharide production of A. blazei Murrill with submerged fermentation is potentially feasible.

Effect of culture media and conditions on polyunsaturated fatty acids production by Mortierella alpina.

To improve the polyunsaturated fatty acid (PUFA) production by Mortierella, culture media and conditions were investigated. M. alpina ATCC 32222 had the highest yield of arachidonic acid, gamma-linolenic acid and linoleic acid among 11 test microbes. Soluble starch at 10% and the mixture of KNO3 and yeast extract at 2:1 (w/w) was the best carbon and nitrogen sources for arachidonic acid and total PUFAs production, respectively. The optimal C/N ratio ranged from 5.1 to 9.0. Each gram of carbon produced 17.4 mg of linoleic acid, 17.0 mg of gamma-linolenic acid, 103.0 mg of arachidonic acid and 194.2 mg of total PUFAs at 20 degrees C, while it yielded 21.4 mg of linoleic acid, 25.6 mg of gamma-linolenic acid, 2.6 mg of gamma-linolenic acid, 110.3 mg of arachidonic acid, 4.3 mg of eicosapentaenoic acid and 218.4 mg of total PUFAs at 12 degrees C. A high degree of unsaturation was found at low temperature incubation. Linseed oil supplementation (1%, w/v) increased the PUFAs production and each gram of carbon produced 403.4 mg of alpha-linolenic acid, 123.1 mg of arachidonic acid, 33.6 mg of eicosapentaenoic acid, 1.68 mg of docosahexaenoic acid and 943.2 mg of total PUFAs. From the optimization of culture media and conditions, PUFAs production increased from 30% to 5 times that was optimal for practical use.

Methane and carbon dioxide emissions from Shan-Chu-Ku landfill site in northern Taiwan.

To investigate the methane and carbon dioxide emissions from landfill, samples were taken of material up to 5 years old from Shan-Chu-Ku landfill located in the northern part of Taiwan. Atmospheric concentrations of carbon dioxide, methane and nitrous oxide ranged from 310 to 530, 2.64 to 20.16 and 0.358 to 1.516 ppmv with the measurement of gas-type open-path Fourier transform infra-red (FTIR) spectroscopy during February 1998 to March 2000, respectively. Average methane emission rate was 13.17, 65.27 and 0.99 mgm(-2)h(-1) measured by the gas chromatography chamber method in 1-2, 2-3 and 5 year-old landfill, respectively. Similarly, average carbon dioxide emission rate was 93.70, 314.60 and 48.46 mgm(-2)h(-1), respectively. About 2-3 year-old landfill had the highest methane and carbon dioxide emission rates among the tested areas, while 5 year-old landfill was the least. Methane emission rate at night in most tested locations was higher than that in the daytime. Total amount of methane and carbon dioxide emission from this landfill was around 171 and 828 ton in 1999, respectively.

Estimation of methane and nitrous oxide emission from paddy fields and uplands during 1990-2000 in Taiwan.

To investigate the greenhouse gases emissions from paddy fields and uplands, methane and nitrous oxide emissions were estimated from local measurement and the IPCC guidelines during 1990-2000 in Taiwan. Annual methane emission from 182,807 to 242,298 ha of paddy field in the first crop season ranged from 8,062 to 12,066 ton, and it was between 16,261 and 25,007 ton for 144,178-211,968 ha in the second crop season with local measurement. The value ranged from 12,132 to 17,465 ton, and from 16,046 to 24,762 ton of methane in the first and second crop season with the IPCC guidelines for multiple aeration treatments, respectively. Annual nitrous oxide emission was between 472 and 670 ton and between 236 and 359 ton in the first and second crop season, respectively. Methane and nitrous oxide emissions from uplands depend on crop, growth season, fertilizer application and environmental conditions. Annual methane emission from upland crops, vegetable, fruit, ornamental plants, forage crops and green manure crops was 138-252, 412-460, 97-100, 3-5, 4-5 and 3-51 ton, respectively. Annual nitrous oxide emission was 1,080-1,976, 1,784-1,994, 2,540-2,622, 31-54, 43-53 and 38-582 ton, respectively. Annual nitrous oxide emission ranged from 91 to 132 ton for 77,593-11,2095 ton of nitrogen-fixing crops, from 991 to 1,859 ton for 3,259,731-6,183,441 ton of non-nitrogen-fixing crops, and from 1.77 to 2.22 Gg for 921,169-1,172,594 ton of chemical fertilizer application. In addition, rice hull burning emitted 19.3-24.2 ton of methane and 17.2-21.5 ton of nitrous oxide, and corn stalk burning emitted 2.1-4.2 ton of methane and 1.9-3.8 ton of nitrous oxide. Methane emission from the agriculture sector was 26421-37914 ton, and nitrous oxide emission was 9810-11,649 ton during 1990-2000 in Taiwan. Intermittent irrigation in paddy fields reduces significantly methane emission; appropriate application of nitrogen fertilization and irrigation in uplands and paddy fields also decreases nitrous oxide emission.