Soil In Taiwan Research Articles

Niche Differentiation of Active Methane-Oxidizing Bacteria in Estuarine Mangrove Forest Soils in Taiwan.

Mangrove forests are one of the important ecosystems in tropical coasts because of their high primary production, which they sustain by sequestering a substantial amount of CO2 into plant biomass. These forests often experience various levels of inundation and play an important role in CH4 emissions, but the taxonomy of methanotrophs in these systems remains poorly understood. In this study, DNA-based stable isotope probing showed significant niche differentiation in active aerobic methanotrophs in response to niche differentiation in upstream and downstream mangrove soils of the Tamsui estuary in northwestern Taiwan, in which salinity levels differ between winter and summer. Methylobacter and Methylomicrobium-like Type I methanotrophs dominated methane-oxidizing communities in the field conditions and were significantly 13C-labeled in both upstream and downstream sites, while Methylobacter were well adapted to high salinity and low temperature. The Type II methanotroph Methylocystis comprised only 10–15% of all the methane oxidizers in the upstream site but less than 5% at the downstream site under field conditions. 13C-DNA levels in Methylocystis were significantly lower than those in Type I methanotrophs, while phylogenetic analysis further revealed the presence of novel methane oxidizers that are phylogenetically distantly related to Type Ia in fresh and incubated soils at a downstream site. These results suggest that Type I methanotrophs display niche differentiation associated with environmental differences between upstream and downstream mangrove soils.

Dissipation of organochlorine insecticide residues in the environment of Taiwan, 1973-1999

Organochlorine insecticides were used in Taiwan for agricultural and public health purposes mainly from 1950 to 1974. In this study, various survey and analysis studies on soil, water, sediment and animals from 1973 to 1999 were compared, temporal trends were analyzed, and the significance was discussed. In 1973, DDT, DDE, DDD, dieldrin, lindane and aldrin were the major organochlorine insecticides found at higher levels in rice paddy soil in Taiwan. In 1981, average total DDTs concentration of surface soil decreased to one-third of the 1973 level. Subsequently in 1994, total DDTs concentration in surface soil again decreased to one-third of the 1981 level. Dieldrin, lindane and aldrin concentrations decreased even faster and were much lower compared to DDT since 1981. Organochlorine insecticide mean concentrations in river water had reached ppt levels from 1973-1976, but were rarely detected in the 1990s. River sediment concentrations showed a rapid decrease from 1973 to 1976, but although there were variations among different rivers in Taiwan, sediment concentrations of lindane, DDT, DDE and aldrin reached a few ppb and were higher in 1981 compared to 1973-1976 on average. In recent years, total organochlorine insecticide concentration decreased to the ppb level, with most individual insecticide concentrations below 1 ppb. Shellfish organochlorine pesticide concentrations were slightly higher than sediment, and shellfish DDT, DDE, aldrin, dieldrin concentrations also showed an increase from 1973 to 1983 on average. The mean concentrations of DDT and aldrin were higher than 10 ppb in shellfish in 1983 and decreased to below the ppb level in the 1990s. Fish muscle contained ppb levels of organochlorine insecticides in 1973. In recent years, most of the organochlorine insecticide concentrations in shellfish and fish were less than 1 ppb except DDE. Duck eggs and human milk had been found to contain sub ppm levels of DDT and DDE in the 1970s and 1980s, but there was few recent data available. Although organochlorine insecticide levels in the environment of Taiwan have fallen fast over the last 26 years, DDTs and other organochlorine insecticide residue levels in higher animals should be determined for their bioaccumulation potential through the food chain.

Influence of soil properties on the bioaccessibility of Cr and Ni in geologic serpentine and anthropogenically contaminated non-serpentine soils in Taiwan

Serpentine minerals with high levels of geologic chromium (Cr) and nickel (Ni) and non-serpentine farmlands polluted by irrigation water causing high anthropogenic Cr and Ni levels are both found in Taiwan. Elevated levels of Cr and Ni in these soils are a concern due to their potential to promote cancer mortality in humans. Bioaccessibility is a crucial factor determining the actual health risk via oral ingestion when children are exposed to metal-contaminated soils. Furthermore, the bioaccessibility of metals varies with the source, soil properties, and fractionation of metals in the soil. Therefore in this study, soil pH, total organic carbon (TOC), texture, and the total concentrations, fractionation, and bioaccessibility of Cr and Ni were analyzed and correlated for soils collected from serpentine mineral-containing deposits and contaminated non-serpentine farmlands. The low bioaccessibility and low mobility of Cr and Ni in serpentine soils suggested that incidental ingesting of soils posed a low health risk; however, the higher bioaccessibility and mobility of Ni in non-serpentine soils contaminated by electroplating wastewater could lead to potential risks for humans. Additionally, a significant difference in the bioaccessibility of Ni was observed between serpentine and non-serpentine soils, but this was not shown for Cr. Accordingly, a correlation analysis showed that Cr bioaccessibility was positively correlated with TOC, with no distinction between serpentine and non-serpentine soils. In contrast, TOC and the fractions of the sequential extraction procedure were significantly correlated with Ni bioaccessibility both in anthropogenically contaminated non-serpentine soils and in natural serpentine soils.

Allorhizobium terrae sp. nov., isolated from paddy soil, and reclassification of Rhizobium oryziradicis (Zhao et al. 2017) as Allorhizobium oryziradicis comb. nov.

A polyphasic taxonomic approach was used to characterize a nitrogen-fixing bacterium, designated strain CC-HIH110T, isolated from paddy soil in Taiwan. Cells of strain CC-HIH110T were Gram-stain-negative, rod-shaped, motile with polar flagella, catalase-positive and oxidase-positive. Optimal growth occurred at 30 °С, pH 7 and 1 % NaCl. Phylogenetic analyses based on 16S rRNA genes revealed a distinct taxonomic position attained by strain CC-HIH110T associated with Rhizobium oryziradicis (98.4 % sequence identity), Allorhizobium vitis (97.8 %), Allorhizobium taibaishanense (97.7 %) and Allorhizobium undicola (96.0 %), and lower sequence similarity to other species. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain CC-HIH110T and the type strains of other closely related species were 71.5-88.6 % and 19.6-35.5 %, respectively. Strain CC-HIH110T contained C16 : 0 3-OH, C14 : 0 3-OH/iso C16 : 1 I and C18 : 1 ω7c/C18 : 1 ω6c as the predominant fatty acids. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, phosphatidylcholine, three unknown aminophospholipids, two unknown phospholipids and an unknown lipid. The major polyamine was homospermidine. The DNA G+C content was 55.0 mol% and the predominant quinone was ubiquinone (Q-10). Based on its distinct phylogenetic, phenotypic and chemotaxonomic traits together with results of comparative 16S rRNA gene sequence, ANI and dDDH analyses, strain CC-HIH110T is proposed to represent a novel Allorhizobium species, for which the name Allorhizobium terrae sp. nov. (type strain CC-HIH110T=BCRC 80932T=JCM 31228T). In addition, Rhizobium oryziradicis is reclassified as Allorhizobium oryziradicis (type strain N19T=ACCC 19962T=KCTC 52413T) comb. nov.

Biodegradation of hexabromocyclododecane by Rhodopseudomonas palustris YSC3 strain: A free-living nitrogen-fixing bacterium isolated in Taiwan.

The persistent organic pollutant, brominated flame retardant, hexabromocyclododecane (HBCD), identified as an emerging contaminant has been detected in various environmental matrix. The increased level of this toxic organic compound in the environment has been associated with serious human health risks. The results obtained from this study revealed that various Rhodopseudomonas palustris strains isolated from paddy soil in Taiwan possessed good HBCD biodegradation capability when they were cultured aerobically. Among these strains, YSC3 was considered as one of the most potential isolates for HBCD degradation. The optimum HBCD biodegradation occurred at neutral pH and at 35°C in all our pH and temperature tests at an initial HBCD concentration of 1ppm. HBCD degradation kinetics generally decreased with the increase of initial HBCD concentration. The study also suggested that the cultivation temperature played a vital role on YSC3 for its initiation of cellular HBCD degradation. The relative-molar ratio of the released bromide ions during the biodegradation of HBCD was observed in the range between 1 and 3.5, suggesting that the debromination reactions occurred. Concomitant with the loss of HBCD, there was a concurrent production of two metabolites, pentabromocyclododecanol and pentabromocyclododecene, which were determined by liquid chromatography and mass spectrometry techniques. On the basis of the obtained results, the possible biodegradation pathways were also proposed in this study.

Effects of aluminum on the cell morphology in the root apices of two pineapples with different Al-resistance characteristics

ABSTRACT Pineapple (Ananas comosus [L.] Merrill) is a commercial crop commonly planted in strongly acid soils in Taiwan. However, aluminum (Al) in strongly acid soils may be toxic and inhibits the root growth of various pineapples. This study evaluated the cell morphology, 1,3-β-glucan, and malondialdehyde (MDA) of the root apex cells of Al-resistant Cayenne and nonresistant Tainung No. 17 pineapples under two Al concentrations (0 and 300 μM AlCl3). An observation using transmission electron microscopy indicated no particular variation in the cells of the root apices of the Cayenne pineapple after a treatment with 300 μM AlCl3. However, apparent changes in the cells of the root apices of the Tainung No. 17 pineapple were observed, for example, separation of the cell wall and cell membrane, enlargement of vacuoles, shrinking and gathering of mitochondria beside the inner cell membrane). The 1,3-β-glucan (callose) and malondialdehyde (MDA) contents in the Cayenne pineapple were not affected by the Al treatment. However, in the Tainung No. 17 pineapple, those contents showed substantial increases under the treatment with 300 μM AlCl3, indicating definite damage on the root apices of Tainung No. 17. The results further revealed that the non-Al-resistance pineapple cultivars should be cultivated on the soil that contains low toxic aluminum.

Landscape Assessment for Stream Regulation Works in a Watershed Using the Analytic Network Process (ANP)

There is varied natural landscape in Taiwan. Erosion and sediment control engineering used to be a major strategy for watershed management and planning but ecological conservation in natural environments and industrial development, as well as the development of a sustainable watershed, have become priorities. This study established the factors that are used for landscape assessment for stream regulation works and their weights using a questionnaire survey of experts with different professional backgrounds in order to determine a method to assess the landscape. The factors, “texture and form”, “color”, and “ecology” were used to assess scenic beauty. The analytic hierarchy process (AHP) and the analytic network process (ANP) were used initially and an expert questionnaire was used to determine the criteria and weights for landscape assessment for watershed stream regulation works. The questionnaire results showed that “integration with natural environment” was the most important factor for the assessment of landscape aesthetics for watershed stream regulation works, followed by “availability of greening and vegetation space”. To preserve scenic beauty after watershed stream regulation works, an expert landscape assessment was undertaken beforehand. This study established a means to integrate the design of engineering structures with the natural landscape. Landscape assessments, strategies for architecture, and landscape design were combined to give an aesthetic solution for soil and water conservation engineering in Taiwan.

Improvement of the K-Factor of USLE and Soil Erosion Estimation in Shihmen Reservoir Watershed

The estimation of soil erosion in Taiwan and many countries of the world is based on the widely used universal soil loss equation (USLE), which includes the factor of soil erodibility (K-factor). In Taiwan, K-factor values are referenced from past research compiled in the Taiwan Soil and Water Conservation Manual, but there is limited data for the downstream area of the Shihmen reservoir watershed. The designated K-factor from the manual cannot be directly applied to large-scale regional levels and also cannot distinguish and clarify the difference of soil erosion between small field plots or subdivisions. In view of the above, this study establishes additional values of K-factor by utilizing the double rings infiltration test and measures of soil physical–chemical properties and increases the spatial resolution of K-factor map for Shihmen reservoir watershed. Furthermore, the established values of K-factors were validated with the designated value set at Fuxing Sanmin from the manual for verifying the correctness of estimates. It is found that the comparative results agree well with established estimates within an allowable error range. Thus, the K-factors established by this study update the previous K-factor system and can be spatially estimated for any area of interest within the Shihmen reservoir watershed and improving upon past limitations.

Taiwan unlawful remediation approach

Soil and groundwater remediation act has been enacted and executed since year 2000 in Taiwan. It has been ten good years till today where lots of remediation techniques progressively employed to improve Taiwan soil and groundwater resource quality. Regulatory agencies, academia, remediation consulting firms, on-site professional engineers all have contribute the proud ten years in terms of soil and groundwater clean-up contribution. However, some of technologies were un-environmental friendly even detrimental and damage to Taiwan precious soil and groundwater resources. In Article one of the current Taiwan soil and groundwater Act, it clearly stated that soil is a precious nature resources. Soil definitely is not a waste, shame on us most of current most commonly employed remediation are unlawful and merely aiming to save time and money consideration without any care to our land. Dig-and-dump and soil acid washing are damaged employed in almost every single local environment agency soil clean-up project. Lot of money, effort and time has been spent during past ten years. Most of the spending is not improving soil quality using Green approach.

Sources identification of PCDD/Fs in soil and atmospheric deposition in Taiwan

PCDD/Fs are among pollutants, which gain major concern from Taiwan government and citizens during industrialization. PCDD/Fs can be emitted into the atmosphere, soil, and water environment in either vapor or solid forms. Atmospheric deposition is the main pathways for atmospheric PCDD/Fs to precipitate on surface soil. In this study, a simultaneous analysis of both soil and deposition PCDD/Fs was done to investigate the relationship between in-soil and deposited PCDD/Fs in Taiwan. Soil samples (n = 84) and atmospheric deposition samples (n = 57) were collected within overlapped periods of time. Geometric mean of 10.4 pg WHO-TEQ/g was found in the soil samples when the geometric mean of atmospheric deposited PCDD/F concentrations was found to be 7.39 pg WHO-TEQ/m2/day. Concentration of PCDD/Fs in samples collected in industrial location were higher than those collected in other locations in all sampling areas. OCDD, OCDF, HpCDD, HpCDF, were the predominant congeners in PCDD/F profile in both soil and atmospheric deposited samples, when 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF were major contributors for PCDD/F fingerprint with WHO-TEQ transformation. Positive Matrix Factorization (PMF) analysis showed that 83% of soil PCDD/Fs correlate with atmospheric deposition process originated from industrial activities (44%) and long range transport activities (39%). Furthermore, the PMF analysis found long range transport, municipal solid water incinerators (MSWIs), industrial waste incinerators (IWIs), electric arc furnace, recycling process of aluminum, sintering plants to be the main sources contributing to atmospheric deposited PCDD/Fs.

The influences of thorny bamboo growth on the bacterial community in badland soils of southwestern Taiwan

AbstractThe badland soils originated from mudstone in southwestern Taiwan are inhospitable for plant growth because of their high‐salinity and poor physicochemical properties. Thorny bamboo is one of the few plants that can survive in these soils. To investigate the responses of the soil bacterial communities to plant cover, bare soils and soils from thorny bamboo plantations were analyzed with the barcoded pyrosequencing technique.ActinobacteriaandProteobacteriapredominated in the bare soil communities, butAcidobacteria,Actinobacteria, andProteobacteriawere the most abundant groups in the thorny bamboo soils. Environmental stress may have selected forActinobacteriain the bare community. Canonical correspondence analysis of the distributions of abundant operational taxonomic units also revealed consistent differences between the communities in the bamboo and bare soils. The bacterial diversity in the bamboo soils was also higher than that in the bare soils. The soluble organic carbon and nitrogen in bamboo soils were significantly higher, but electrical conductivity was lower than that in the bare soils. These soil properties, as well as soil pH, were related to the structure and diversity of the bacterial communities. Statistical analyses also indicated that these factors affected the distribution ofAcidobacteria,Actinobacteria,Alphaproteobacteria, andGammaproteobacteria. Analysis of thiocyanate oxidation activity revealed higher activity in the bare than in the bamboo soils, further suggesting differences in structure and metabolic activity between bamboo and bare soil microbial communities. Apparently, growth of thorny bamboo in the badland soil changed soil properties, which in turn directly and/or indirectly affected soil bacterial structure and diversity.

National surveillance of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins/furans in soil in Taiwan

In this study, the polychlorinated dibenzo-p-dioxin/furan (PCDD/F) levels in 381 soil samples coming from different background areas (n = 238) and contaminated areas (n = 143) in Taiwan were investigated from 2011 to 2015 using high resolution gas chromatograph/high resolution mass spectrometry (HRGC/HRMS). The contaminated areas showed higher PCDD/F contamination as compared to the background areas (1230 vs 749 pg/g dry weight (dw)); 14.0 vs 6.25 pg WHO2005-TEQ/g dw). The lowest levels were recorded in the outlying islands (1.28 pg WHO2005-TEQ/g dw). PCDD/F congener distribution profiles in the background and contaminated areas as well as on the islands varied. OCDD was the dominant congener in almost all locations, including the northern background (87.7%) and central contaminated (74.2%) areas. Other dominant species included OCDF and 1,2,3,4,6,7,8-HpCDD. Levels of PCDD/F-TEQs in Taiwanese soils, including the background areas, were higher than in some developing countries and regions with global background levels due to high industrialization except for the contaminated areas. Geographic differences in dioxin-contaminated soils were also shown in this study. Higher soil dioxin-TEQs were observed in locations with high populations and population densities. Despite the limitations, the economic status of Taiwan represented by the annual averaged family income (AAFI) was positively correlated to soil dioxin-TEQs.

Molecular characterization of cadmium-resistant Cupriavidus spp. and Ralstonia solanacearum isolated from soil and plants in Taiwan

Cadmium is a natural heavy-metal element. It is highly toxic and a vital industrial pollutant to the environment. In order to survive in heavy-metal polluted environments, some bacteria can withstand high concentrations of heavy metals in environment due to their specific mechanisms, including the transport of heavy metal ions out of the cell. Three kinds of membrane-bound-proteins are known to participate in this transport. The objective of this study was to determine the cadmium-resistant properties and possible mechanism among strains of Cupriavidus metallidurans (= Ralstonia eutropha), C. Taiwanensis (=R. Taiwanensis) and Ralstonia solanacearum isolated from soil and plants in Taiwan. Strains tested include six strains, rcd 6, 8, 19 (C. metallidurans) and rcd 12, 14, 21 (C. Taiwanensis), from cadmium-polluted soil, seventeen strains, nod 1 to nod 5 and nod s1 to s12 (C. Taiwanensis) from root nodules of two Mimosa species (M. pudica and M. diplotricha), and ten strains of R. solanacearum isolated from different diseased plants. Sequence analysis of 16S-23S rDNA ITS and nifH gene regions were used to confirm the taxonomic classification of these bacteria. However, the 624-bp PCR product of nifH gene was only amplified from strains nod 1 to nod 3 and nod s1 to s12, but not from other tested strains of Cupriavidus and Ralstonia spp. These tested strains could tolerate cadmium within the range from 0.67 to 6.70 mM. The gene, czcC, thought to encode the outer membrane factor (OMF) of czc efflux system, was found in fifteen tested strains (rcd 6, 8, 12, 14, 19, 21; nod s1 to s6, s9, s11; PSS161) by PCR. Especially, strains rcd 12, 14, and 21 which could tolerate higher cadmium concentration (6.70 mM) harbored the entire czc operon. In addition, the PCR products revealed that cadmium-tolerant strains contained at least a portion of the czc operon and efflux mechanism was confirmed by cadmium uptake test. The results here indicated that cadmium resistant capability in Cupriavidus spp. and R. solanacearum was related to the presence of czcC or czc operon.

Diversity and characterization of Azotobacter isolates obtained from rice rhizosphere soils in Taiwan

Azotobacter species, free-living nitrogen-fixing bacteria, have been used as biofertilizers to improve the productivity of non-leguminous crops, including rice, due to their various plant growth-promoting traits. The purposes of this study were to characterize Azotobacter species isolated from rice rhizospheres in Taiwan and to determine the relationship between the species diversity of Azotobacter and soil properties. A total of 98 Azotobacter isolates were isolated from 27 paddy fields, and 16S rRNA gene sequences were used to identify Azotobacter species. The characteristics of these Azotobacter strains were analyzed including carbon source utilization and plant growth-promoting traits such as nitrogen fixation activity, indole acetic acid production, phosphate-solubilizing ability, and siderophore secretion. Of the 98 strains isolated in this study, 12 were selected to evaluate their effects on rice growth. Four species of Azotobacter were identified within these 98 strains, including A. beijerinckii, A. chroococcum, A. tropicalis, and A. vinelandii. Of these four species, A. chroococcum was predominant (51.0%) but A. beijerinckii had the highest level of nucleotide diversity. Strains within individual Azotobacter species showed diverse profiles in carbon source utilization. In addition, the species diversity of Azotobacter was significantly related to soil pH, Mn, and Zn. Members of the same Azotobacter species showed diverse plant growth-promoting traits, suggesting that the 98 strains isolated in this study may not equally effective in promoting rice growth. Of the 12 strains evaluated, A. beijerinckii CHB 461, A. chroococcum CHB 846, and A. chroococcum CHB 869 may be used to develop biofertilizers for rice cultivation because they significantly promoted rice growth. This study contributes to the selection of suitable Azotobacter strains for developing biofertilizer formulations and soil management strategies of Azotobacter for paddy fields.

Oryzomicrobium terrae gen. nov., sp. nov., of the family Rhodocyclaceae isolated from paddy soil.

A polyphasic approach was used to characterize a novel bacterium, designated strain TPP412T, isolated from a paddy soil in Taiwan. Strain TPP412T was Gram-stain-negative, facultatively anaerobic, rod-shaped, motile with a single polar flagellum and lacked bacteriochlorophyll. Growth was observed at 24-45 °C (optimal 25 °C), at pH 5.0-10.0 (optimal pH 7.0) and with 0-0.75 % (w/v) NaCl. Strain TPP412T showed highest 16S rRNA gene sequence similarity to members of the genera Rhodocyclus (94.1-94.5 %), Azospira (93.9-94.5 %) and Propionivibrio (93.4-94.4 %) and established a discrete taxonomic lineage in phylogenetic analysis. The major fatty acids found in strain TPP412T were C12 : 0, C12 : 0 3-OH, iso-C15 : 0 3-OH, C16 : 0, C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c. The major polar lipids consisted of phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and an unidentified lipid. The polyamine pattern showed a predominance of putrescine and a minor amount of spermidine. The DNA G+C content was 58.4 mol% and the predominant quinone system was ubiquinone-8 (Q-8). The low 16S rRNA gene sequence similarity values (≤94.5%) and distinct phylogenetic clustering clearly distinguished strain TPP412T from other representatives of the family Rhodocyclaceae. Based on the discrete phylogenetic, phenotypic and chemotaxonomic traits together with results of comparative 16S rRNA gene sequence analysis, strain TPP412T is considered to represent a novel species of a new genus in the family Rhodocyclaceae, for which the name Oryzomicrobium terrae gen. nov., sp. nov. is proposed. The type strain of Oryzomicrobium terrae is TPP412T (=BCRC 80905T=JCM 30814T).

The oil-contaminated soil diazotroph Azoarcus olearius DQS-4T is genetically and phenotypically similar to the model grass endophyte Azoarcus sp. BH72.

The genome of Azoarcus olearius DQS-4T , a N2 -fixing Betaproteobacterium isolated from oil-contaminated soil in Taiwan, was sequenced and compared with other Azoarcus strains. The genome sequence showed high synteny with Azoarcus sp. BH72, a model endophytic diazotroph, but low synteny with five non-plant-associated strains (Azoarcus CIB, Azoarcus EBN1, Azoarcus KH32C, A. toluclasticus MF63T and Azoarcus PA01). Average Nucleotide Identity (ANI) revealed that DQS-4T shares 98.98% identity with Azoarcus BH72, which should now be included in the species A. olearius. The genome of DQS-4T contained several genes related to plant colonization and plant growth promotion, such as nitrogen fixation, plant adhesion and root surface colonization. In accordance with the presence of these genes, DQS-4T colonized rice (Oryza sativa) and Setaria viridis, where it was observed within the intercellular spaces and aerenchyma mainly of the roots. Although they promote the growth of grasses, the mechanism(s) of plant growth promotion by A. olearius strains is unknown, as the genomes of DQS-4T and BH72 do not contain genes for indole acetic acid (IAA) synthesis nor phosphate solubilization. In spite of its original source, both the genome and behaviour of DQS-4T suggest that it has the capacity to be an endophytic, nitrogen-fixing plant growth-promoting bacterium.

An Amphiprotic Novel Chitosanase from Bacillus mycoides and Its Application in the Production of Chitooligomers with Their Antioxidant and Anti-Inflammatory Evaluation.

The objectives of this investigation were to produce a novel chitosanase for application in industries and waste treatment. The transformation of chitinous biowaste into valuable bioactive chitooligomers (COS) is one of the most exciting applications of chitosanase. An amphiprotic novel chitosanase from Bacillus mycoides TKU038 using squid pen powder (SPP)-containing medium was retrieved from a Taiwan soil sample, which was purified by column chromatography, and characterized by biochemical protocol. Extracellular chitosanase (CS038) was purified to 130-fold with a 35% yield, and its molecular mass was roughly 48 kDa. CS038 was stable over a wide range of pH values (4–10) at 50 °C and exhibited an optimal temperature of 50 °C. Interestingly, the optimum pH values were estimated as 6 and 10, whereas CS038 exhibited chitosan-degrading activity (100% and 94%, respectively). CS038 had Km and Vmax values of 0.098 mg/mL and 1.336 U/min, separately, using different concentrations of water-soluble chitosan. A combination of the high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometer data revealed that the chitosan oligosaccharides obtained from the hydrolysis of chitosan by CS038 comprise oligomers with multiple degrees of polymerization (DP), varying from 3–9, as well as CS038 in an endolytic fashion. The TKU038 culture supernatant and COS mixture exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities. The COS activities were dose dependent and correlated to their DP. The COS with high DP exhibited enhanced DPPH radical scavenging capability compared with COS with low DP. Furthermore, the COS exhibited inhibitory behavior on nitric oxide (NO) production in murine RAW 264.7 macrophage cells, which was induced by Escherichia coli O111 lipopolysaccharide (LPS). The COS with low DP possesses a more potent anti-inflammatory capability to decrease NO production (IC50, 76.27 ± 1.49 µg/mL) than that of COS with high DP (IC50, 82.65 ± 1.18 µg/mL). Given its effectiveness in production and purification, acidophilic and alkalophilic properties, stability over ranges of pH values, ability to generate COS, antioxidant activity, and anti-inflammatory, CS038 has potential applications in SPP waste treatment and industries for COS production as a medical prebiotic.

Investigation of biogeochemical controls on the formation, uptake and accumulation of methylmercury in rice paddies in the vicinity of a coal-fired power plant and a municipal solid waste incinerator in Taiwan

Recent studies have shown that rice consumption is another critical route of human exposure to methylmercury (MeHg), the most toxic and accumulative form of mercury (Hg) in the food web. Yet, the mechanisms that underlie the production and accumulation of MeHg in the paddy ecosystem are still poorly understood. In 2013 and 2014, we conducted field campaigns and laboratory experiments over a rice growing season to examine Hg and MeHg cycling, as well as associated biogeochemistry in a suite of paddies close to a municipal solid waste incinerator and a coal-fired power plant station in Taiwan. Concentrations of total Hg and MeHg in paddy soil and rice grain at both sites were low and found not to exceed the control standards for farmland soil and edible rice in Taiwan. However, seasonal variations of MeHg concentrations observed in pore water samples indicate that the in situ bioavailability of inorganic Hg and activity of Hg-methylating microbes in the rhizosphere increased from the early-season and peaked at the mid-season, presumably due to the anoxia created under flooded conditions and root exudation of organic compounds. The presence of Hg-methylators was also confirmed by the hgcA gene detected in all root soil samples. Subsequent methylation tests performed by incubating the root soil with inorganic Hg and an inhibitor or stimulant specific for certain microbes further revealed that sulfate-reducers might have been the principal Hg-methylting guild at the study sites. Interestingly, results of hydroponic experiments conducted by cultivating rice in a defined nutrient solution amended with fixed MeHg and varying levels of MeHg-binding ligands suggested that chemical speciation in soil pore water may play a key role in controlling MeHg accumulation in rice, and both passive and active transport pathways seem to take place in the uptake of MeHg in rice roots.

Forms and distribution of phosphorus in a placic podzolic toposequence in a subtropical subalpine forest, Taiwan

Phosphorous (P) is a limiting nutrient in subtropical and tropical mountain forests, where placic podzolization further restricts mobilization and the transformation of P fractionation. We examined how the distribution of different forms of phosphorus varied with increasing placic podzolization along a toposequence of seven pedons in subalpine forest soils in Taiwan. We used a variation of the Hedley procedure for the chemical sequential extraction of P and electron-probe micro-analysis (EPMA) to determine the micro-distribution and associations of P with other elements in selected illuvial horizons. The fractionation and P:Ti ratios indicated that P is not greatly depleted during the development of placic conditions. It is instead increasingly sequestered in sesquioxides and their organic complexes in the illuvial B horizons and in the accreting peaty surface layers. The EPMA micro-mapping in the Bsm horizons revealed that P was mainly associated with illuviated iron but not with aluminum. Forests on these soils must cope with a combination of an apparently adequate P supply and an increasingly stagnic moisture regime. When placic conditions develop in the soil, P appears to be increasingly sequestered in the sesquioxides and their complexes with illuvial humus in the B horizons and in the accreting organic epipedon.

Azospirillum agricola sp. nov., a nitrogen-fixing species isolated from cultivated soil.

A polyphasic approach was used to characterize a novel nitrogen-fixing bacterial strain, designated CC-HIH038T, isolated from cultivated soil in Taiwan. Cells of strain CC-HIH038T were Gram-stain-negative, facultatively aerobic and spiral-shaped, with motility provided by a single polar flagellum. The 16S rRNA gene sequence analysis of strain CC-HIH038T showed highest sequence similarity to Azospirillum doebereinerae (98.0 %), Azospirillum thiophilum (97.5 %), Azospirillum rugosum (97.4 %) and Azospirillum zeae (97.2 %) and lower sequence similarity ( < 97.0 %) to all other species of the genus Azospirillum. According to DNA-DNA association, the relatedness values of strain CC-HIH038T with A. doebereinerae, A. thiophilum, A. rugosum and A. zeae were 51.8 %, 41.2 %, 56.5 % and 37.5 %, respectively. Strain CC-HIH038T was able to grow at 20-37 °C and pH 7.0-8.0. Strain CC-HIH038T gave positive amplification for dinitrogen reductase (nifH gene); the activity was recorded as 8.4 nmol ethylene h- 1. The predominant quinone system was ubiquinone Q-10 and the DNA G+C content was 68.8 mol%. The major fatty acids found in strain CC-HIH038T were C16 : 0, iso-C18 : 0, C16 : 0 3-OH, C14 : 0 3-OH/iso-C16 : 1 and C18 : 1ω7c/C18 : 1ω6c. Based on the distinct phylogenetic, phenotypic and chemotaxonomic traits together with results of comparative 16S rRNA gene sequence analysis, strain CC-HIH038T is considered to represent a novel species in the genus Azospirillum, for which the name Azospirillum agricola sp. nov. is proposed. The type strain is CC-HIH038T ( = BCRC 80909T = JCM 30827T).