Aflatoxins (AFs), a class of toxins produced by certain species of the genus
, occasionally contaminate food and cause serious damage to human health and the economy. AFs contamination is a global ...problem, and there is a need to develop effective strategies to control aflatoxigenic fungi. In this study, we focused on isothiocyanates (ITCs) as potential chemical agents for the control of aflatoxigenic fungi. We quantitatively evaluated the effects of four ITCs (allyl ITC (AITC), benzyl ITC (BITC), and methyl and phenylethyl ITCs) in dissolved and gaseous states on the growth and aflatoxin B
production of
. In experiments using dissolved ITCs, BITC was found to be the strongest inhibitor of growth and aflatoxin B
production by
. Meanwhile, in the gaseous state, AITC strongly inhibited the
growth. When the concentration of ITCs in the liquid medium was quantified over time, AITC levels decreased to below the detection limit within 24 h, whereas BITC levels remained stable even after 48 h. These results suggested that when ITCs are utilized to control aflatoxigenic fungi, it is necessary to use them in a dissolved or gaseous state, depending on their volatility.
We compared the influences of grazing by the bacterivorous nanoflagellate Poterioochromonas sp. strain DS on ultramicrobacterial Actinobacteria affiliated with the Luna-2 cluster and ...ultramicrobacterial Betaproteobacteria of the species Polynucleobacter cosmopolitanus. These bacteria were almost identical in size (<0.1 μm³) and shape. Predation on a Polynucleobacter strain resulted in a reduction of >86% relative to the initial bacterial cell numbers within 20 days, while in comparable predation experiments with nine actinobacterial strains, no significant decrease of cell numbers by predation was observed over the period of greater-than-or-equal39 days. The differences in predation mortality between the actinobacterial strains and the Polynucleobacter strain clearly demonstrated size-independent grazing resistance for the investigated ACTINOBACTERIA: Importantly, this size-independent grazing resistance is shared by all nine investigated Luna-2 strains and thus represents a group-specific trait. We investigated if an S-layer, previously observed in an ultrastructure study, was responsible for the grazing resistance of these strains. Experiments aiming for removal of the S-layer or modification of cell surface proteins of one of the grazing-resistant strains by treatment with lithium chloride, EDTA, or formaldehyde resulted in 4.2- to 5.2-fold higher grazing rates in comparison to the levels for untreated cells. These results indicate the protective role of a proteinaceous cell surface structure in the size-independent grazing resistance of the actinobacterial Luna-2 strains, which can be regarded as a group-specific trait.
Biogas digestive effluent (BDE) is a nutrient-enriched source that can be utilized as an organic fertilizer for rice cultivation without synthetic fertilizer (SF) application. However, a primary ...concern is the stimulation of methane (CH4) emissions due to the enrichment of the labile organic carbon, a favorite substrate of methanogenic archaea. Methanotrophs potentially reduce greenhouse gas (GHG) emissions from rice fields owing to metabolizing CH4 as a carbon source and energy. We therefore examined the effect of the application of methanotroph-inoculated BDE to the rice cultivated paddy soil on GHG emissions and rice productivity under a pot experiment. Methanotrophs (Methylosinus sp. and Methylocystis sp.), isolated from the Vietnamese Mekong Delta’s rice fields, were separately inoculated to the heated BDE, followed by a 5-day preincubation. Methanotroph-inoculated BDE was supplied to rice cultivation to substitute SF at 50% or 100% in terms of nitrogen amount. The results showed that the total CH4 emissions increased ~34% with the application of BDE. CH4 emissions were significantly reduced by ~17–21% and ~28–44% under the application of methanotroph-inoculated BDE at 100% and 50%, respectively. The reduction in CH4 was commensurate with the augmentation of pmoA transcript copy number under methanotroph-inoculated BDE. In addition, methanotroph-inoculated BDE application did not increase nitrous oxide (N2O) emissions and adversely affect rice growth and grain productivity. This study highlighted the BDE-recirculated feasibility for a lower CH4 emission rice production based on methanotrophs where high CH4-emitting fields were confirmed.
Background
: Biochar is a promising material in mitigating greenhouse gases (GHGs) emissions from paddy fields due to its remarkable structural properties. Rice husk biochar (RhB) and melaleuca ...biochar (MB) are amendment materials that could be used to potentially reduce emissions in the Vietnamese Mekong Delta (VMD). However, their effects on CH
4
and N
2
O emissions and soil under local water management and conventional rice cultivation have not been thoroughly investigated.
Methods
: We conducted a field experiment using biochar additions to the topsoil layer (0-20 cm). Five treatments comprising 0 t ha
-1
(CT0); 5 t ha
-1
(RhB5) and 10 t ha
-1
(RhB10), and 5 t ha
-1
(MB5) and 10 t ha
-1
(MB10) were designed plot-by-plot (20 m
2
) in triplicates.
Results
: The results showed that biochar application from 5 to 10 t ha
-1
significantly decreased cumulative CH
4
(24.2-28.0%, RhB; 22.0-14.1%, MB) and N
2
O (25.6-41.0%, RhB; 38.4–56.4%, MB) fluxes without a reduction in grain yield. Increasing the biochar application rate further did not decrease significantly total CH
4
and N
2
O fluxes but was seen to significantly reduce the global warming potential (GWP) and yield-scale GWP in the RhB treatments. Biochar application improved soil Eh but had no effects on soil pH. Whereas CH
4
flux correlated negatively with soil Eh (
P <
0.001;
r
2
= 0.552, RhB;
P <
0.001;
r
2
= 0.502, MB). Ameliorating soil aeration and functions by adding RhB and MB resulted in improving soil physicochemical properties, especially significant SOM and AN boosting, which indicate better soil health, structure, and fertility.
Conclusions
: Biochar supplementation significantly reduced CH
4
and N
2
O fluxes and improved soil mineralization and physicochemical properties toward beneficial for rice plants. The results suggest that the optimal combination of biochar-application rates and effective water-irrigation techniques for soil types in the MD should be further studied in future works.
Acid sulfate soil (ASS) has major problems related to phosphorus deficiency and high potential for N2O emissions, as well as strong acidity. The objective of this study was to evaluate the effects of ...rice husk biochar and compost on P availability and greenhouse gas (GHG) emissions in ASS in in vitro incubation studies. An ASS was amended with two types of rice husk biochar (at rates of 0 g kg−1, 20 g kg−1, and 50 g kg−1, equivalent to 0 Mg ha−1, 20 Mg ha−1, and 50 Mg ha−1, assuming that bulk density was 1 g cm−3 and evenly applied for 10 cm in depth) and compost (at rates of 0 g kg−1, 10 g kg−1, and 20 g kg−1, equivalent to 0 Mg ha−1, 10 Mg ha−1, and 20 Mg ha−1) and incubated. Application of compost increased labile P by 100% and 200% at rates of 10 g kg−1 and 20 g kg−1, respectively. Both biochars showed an increase in NaHCO3-soluble inorganic P by 16% to 30%, decreases in NaOH-soluble inorganic P and NaHCO3-soluble organic P. N2O emissions were significantly decreased by 80% by a biochar with a higher surface area and higher NH4+ adsorption capacity at a rate of 50 g kg−1 as compared with those in un-amended soil. In contrast, compost amendment at a rate of 10 g kg−1 significantly increased N2O emission by 150%. These results suggest that in ASS, whilst compost is more effective in improving P availability, biochar is more effective in mitigating GHG emissions, emphasizing that fundamental characteristics of organic amendments influenced the outcomes in terms of desirable effects.
Đề tài nghiên cứu được thực hiện nhằm mục tiêu đánh giá tính chất vật lý, hóa học đất trong và ngoài đê bao ngăn lũ ở nhóm đất phèn ở Tri Tôn và đất phù sa cổ ở Tịnh Biên. Số lượng mẫu đất được thu ...ngẫu nhiên trên mỗi nhóm đất là 32 mẫu gồm: 16 mẫu trong đê (vùng lúa 3 vụ) và 16 mẫu ngoài đê (lúa 2 vụ). Kết quả nghiên cứu cho thấy việc canh tác lúa 3 vụ trong đê bao đã làm pH đất trong đê thấp hơn so với pH đất ngoài đê; EC của đất trong đê cao hơn so với EC của đất ngoài đê. Hàm lượng chất hữu cơ tầng mặt trong đê (3 vụ lúa) cao hơn so với đất ngoài đê (2 vụ lúa). Từ đó dẫn đến khả năng trao đổi cation (CEC), đạm tổng số của đất trong đê cũng cao hơn so với đất ngoài đê, đặc biệt ở tầng đất mặt Ap. Trong khi đó, hàm lượng lân tổng số và kali tổng số khác biệt không có ý nghĩa thống kê ở cả hai điểm nghiên cứu. Độ nén dẽ của tầng đất Bg luôn cao hơn ở đất trong đê so với đất ngoài đê ở cả hai điểm nghiên cứu Tri Tôn và Tịnh Biên thể hiện qua độ xốp và hệ số thấm thấp, dung trọng và độ chặt của đất cao.
The heterotrophic, aerobic, facultatively anaerobic under denitrifying conditions, catalase- and oxidase-positive, non-motile strain MT-CBb6A5(T), which was isolated from an acidic lake located in ...Wisconsin (USA), was characterized. The strain grew on NSY medium over a temperature range of 15-30 °C and a NaCl range of 0.0-0.3 % (w/v). The predominant fatty acids were C(16 : 0), C(18 : 1)ω7c, 11-methyl C(18 : 1)ω7c, feature 3 (including C(16 : 1)ω7c), and feature 2 (including C(14 : 0) 3-OH). The DNA G+C content of the strain was 40.3 mol%. Phylogenetic analysis as well as strong similarities in phenotypic and chemotaxonomic traits indicated the affiliation with the genus Polynucleobacter. 16S rRNA gene sequence similarity values with the two described species of the genus Polynucleobacter ranged from 95.6 to 96.0 %. The strain differs from the two described species of the genus Polynucleobacter in the ability to assimilate oxalic and glycolic acids, and in the presence of the fatty acids C(15 : 1)ω8c and C(16 : 0) 3-OH as well as in quantitative differences in fatty acid composition. It has to be assumed that the strain shares with other free-living bacteria of the genus Polynucleobacter a planktonic lifestyle in the water column of freshwater habitats. Based on the phylogeny revealed and the chemotaxonomic and phenotypic differences from Polynucleobacter necessarius and Polynucleobacter cosmopolitanus, we propose to establish the novel species Polynucleobacter rarus sp. nov. with the type strain MT-CBb6A5(T) ( = DSM 21648(T) = CIP 109928(T)).
Độc cấp tính và ảnh hưởng của thuốc bảo vệ thực vật hoạt chất quinalphos đến enzyme cholinesterase (ChE) ở tôm càng xanh(Macrobrachium rosenbergii)giai đoạn hậu ấu trùng 34 ngày tuổi được đánh ...giánhằm xác định giá trị LC50 của hoạt chất này và ảnh hưởng của thuốc đến ChE trong cơtôm ở nồng độ dưới ngưỡng gây chết. Phương pháp nước tĩnh, không thay nước được áp dụng để xác định LC50vàảnh hưởng của quinalphos ở nồng độ 1%, 10% và 20% LC50-96h đến ChEcủa tômtrong 48 giờ. Kết quả ghi nhậnquinalphos rất độc đối với tôm càng xanh, LC50-96h là 0,69 µg/L. ChE ở thịt tôm rất nhạy cảm với hoạt chất quinalphos; ở nồng độ 1%LC50-96h, quinalphos đã gây ức chế ChE ở cơ tôm đến mức có thể gây ảnh hưởng bất lợi cho đa số thủy sinh vật. Tỷ lệ ức chế ChE đạt cao nhất ở thời điểm 24 giờ sau phơi nhiễm và lần lượt là 43,3%, 44,1% và 58,6% ởcác nghiệm thức 1%, 10% và 20% LC50-96 giờ. Kết quả cho thấy quinalphos độc cấp tính cao đối với tôm càng xanh giai đoạn hậu ấu trùng và ChE tôm rất nhạy cảm với thuốc này.
To explore the utility of artificial sweeteners (Acesulfame: ACE; sucralose: SUC; saccharin: SAC; cyclamate: CYC) as molecular markers and to establish a historical benchmark of the water pollution ...status in the 2010 decade, 272 surface water samples, including river water, sewage, and livestock wastewater, were collected from African (Ghana, Kenya, Mozambique, South Africa), Asian (Vietnam, Indonesia, Thailand, Philippines, Cambodia, Malaysia, India, and Japan) and Middle Eastern (Iran and Lebanon) countries during 2010–2019 and were analyzed for the artificial sweeteners by high performance liquid chromatograph with tandem mass spectrometer coupled with online solid-phase extractor. ACE was most frequently detected (87% of the samples) due to its widespread use and lower detection limit (2 ng/L). SUC was less frequently detected (51%) because of its lower sensitivity and detection limit of 100 ng/L, and less widespread use in some low-income countries, probably due to its higher price. SAC and/or CYC were abundant in surface waters of most countries, despite their biodegradable nature. This was ascribed to intensive usage of SAC and CYC and extensive inputs of untreated sewage to rivers due to limited installation of sewage treatment systems. Concentrations of the sweeteners were higher in urbanized rivers (~1 μg/L to ~100 μg/L) than those in corresponding suburban and rural sites, reflecting spatial patterns of sewage inputs. Furthermore, concentrations of the sweeteners were positively correlated with those of linear alkylbenzenes (LABs) for all countries except Malaysia. These results confirm the utility of artificial sweeteners as indicators of sewage inputs. SAC and CYC could be indicators of untreated sewage inputs. ACE has proved to be the most sensitive and reliable marker to assess inputs of sewage, i.e., both treated and untreated, to surface waters. However, ACE concentrations in secondary effluents and receiving waters in Tokyo decreased two orders of magnitude from 2011 to 2019, while sucralose did not show such a marked decrease. This is probably due to the upgrading of activated sludge treatment, i.e., introducing anaerobic-anoxic-oxic (A2O) treatment and resultant higher removal of ACE. Therefore, the measurement of multiple markers, including SUC, is recommended for long-term monitoring.
Nghiên cứu được thực hiện với mục tiêu đánh giá ảnh hưởng của vật liệu hữu cơ lên quần thể vi sinh vật, sự phát thải khí methane và một số đặc tính dinh dưỡng đất theo giai đoạn sinh trưởng của cây ...lúa tại huyện Trần Đề. Thí nghiệm được bố trí khối hoàn toàn ngẫu nhiên với ba nghiệm thức (NT) (n=3). Kết quả thí nghiệm cho thấy NT2-Biochar hoặc NT3-bổ sung phân gà (PHC) giúp gia tăng mật số nấm tổng số, vi khuẩn tổng số, nhóm vi khuẩn phân hủy cellulose, cố định đạm, hòa tan lân cao hơn so với NT1-khuyến cáo (KC). Hàm lượng chất hữu cơ, P dễ tiêu, Pts trong đất ở NT2-Biochar đạt cao hơn so với các NT còn lại. Tổng lượng khí CH4 phát thải từ NT2-Biochar đạt thấp hơn so với các NT còn lại. Tuy nhiên năng suất lúa của các NT khác biệt không có ý nghĩa thống kê. Kết quả của nghiên cứu cho thấy việc bổ sung biochar hoặc phân gà kết hợp với phân vô cơ theo khuyến cáo giúp gia tăng quần thể vi sinh vật có lợi, giúp cải thiện một số tính chất đất trồng lúa chuyên canh và bổ sung biochar giúp giảm lượng khí CH4 phát thải trong vụ Đông Xuân 2018-2019.
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