Sulfide Production by Sulfate Reducing Bacteria with Lactate as Feed in an Upflow Anaerobic Fixed Film Reactor

The sulfate reducing bacteria (SRB) have the capability of reducing sulfate (SO4-2) under anaerobic conditions into sulfide (S-2) which can precipitate metals as metal sulfides. The optimum conditions for sulfide production by SRB utilizing lactate, in an upflow anaerobic fixed film reactor (UAFFR) were not previously established. The main objective of this research was to investigate these conditions for the growth of SRB to ensure the highest sulfide production under consistent behaviour of the system. Substrate containing lactate as the organic carbon source along with sulfate, nitrogen and phosphorus as the required nutrients was used as a feed to the UAFER which was seeded with SRB. It was found that an optimum sulfide production occurred with an organic loading rate (OLR) of 6 kg d-1 m-3, while the theoretical oxygen demand to sulfate ratio (ThOD/SO4) ranged from 1.5 to 2.25. Also, the optimum total nitrogen and phosphorus demands were determined to be about 250 and 50 mg L-1 respectively. A total nitrogen concentration above 600 mg L-1 started showing toxicity and lowered the sulfide production. The optimum ThOD:N:P for sulfide production and growth of SRB in the UAFFR was 100:5:1 under optimum conditions.     

Performance of Anaerobic Biotrickling Filter and Its Microbial Diversity for the Removal of Stripped Disinfection By-products

The objective of this research was to evaluate the biodegradation of chloroform by using biotrickling filter (BTF) and determining the dominant bacteria responsible for the degradation. The research was conducted in three phases under anaerobic condition, namely, in the presence of co-metabolite (phase I), in the presence of co-metabolite and surfactant (phase II), and in the presence of surfactant but no co-metabolite (phase III). The results showed that the presence of ethanol as a co-metabolite provided 49% removal efficiency. The equivalent elimination capacity (EC) was 0.13 g/(m³ h). The addition of Tomadol 25-7 as a surfactant in the nutrient solution increased the removal efficiency of chloroform to 64% with corresponding EC of 0.17 g/(m³ h). This research also investigated the overall microbial ecology of the BTF utilizing culture-independent gene sequencing alignment of the 16S rRNA allowing identification of isolated species. Taxonomical composition revealed the abundance of betaproteobacteria and deltaproteobacteria with species level of 97%. Azospira oryzae (formally dechlorosoma suillum), Azospira restrica, and Geobacter spp. together with other similar groups were the most valuable bacteria for the degradation of chloroform.     

Evolution of Chemical Composition and Microbial Activity during Storage of Compost-Based Mixes

? Horticultural substrates composed of equal parts of peat and compost (v/v) were stored for a period of 24 weeks. The chemical properties and the microbial activity were determined periodically for a wet mix (55% moisture), a dry mix (25% moisture) and a wet mix amended with feather meal. Results showed that electrical conductivity and major nutrients increased with the length of the storage period whereas pH, ammonium and minor elements with the exception of manganese were strongly reduced. The pH and the chemical composition of the dry mix were not affected during storage. Feather meal actively stimulated the microorganisms within few weeks and raised electrical conductivity and nitrates at the end of storage. It was concluded that changes which occurred during storage were related to the microbial activity.     

间隙灌溉和控释肥施用对稻田土壤产甲烷微生物的影响

间隙灌溉和控释肥施用影响稻田CH_4的产生和排放,然而其微生物机理尚不清楚。本研究通过采集稻季田间原位试验新鲜土样,采用核酸定量技术(qPCR)和末端限制性片段长度多态性(T-RFLP)技术,研究间隙灌溉和控释肥施用对稻田土壤产甲烷微生物群落丰度和结构的影响。结果表明,稻季CH_4排放量与古菌、产甲烷菌(mcr A基因)和甲烷氧化菌(pmo A基因)数量均呈极显著正相关关系(P0.01),而与细菌数量无显著相关性。间隙灌溉显著影响产甲烷菌和甲烷氧化菌数量的季节变化,其中烤田抑制产甲烷菌生长,而对甲烷氧化菌数量没有显著影响。与尿素相比,施用控释肥增加了稻田土壤细菌、古菌和产甲烷菌数量,降低了甲烷氧化菌数量。土壤古菌群落的优势T-RFs片段为184bp和391bp,其中184bp片段的相对丰度随着间隙灌溉的进行由45%~55%降低到23%~30%;而391bp片段则相反,其相对丰度由12%~18%增加到23%~26%。典型相关性分析(CCA)表明间隙灌溉显著影响土壤古菌群落结构(P0.001),而控释肥施用对土壤古菌群落结构没有明显影响。     

Nutrient Reduction in Stormwater Pond Discharge Using a Chamber Upflow Filter and Skimmer (CUFS)

Stormwater runoff is a known pollutant source capable of causing surface water degradation, especially in highly populated areas such as Central Florida. Wet detention ponds manage this stormwater, but most of the ponds do not remove enough nutrients, specifically nitrogen and phosphorus, to meet total maximum daily load regulations. This paper presents the use of a chamber upflow filter and skimmer (CUFS) filled with a specific green sorption medium as process modification of stormwater retention ponds, which can increase the removal of nitrogen and phosphorus in the stormwater runoff. Green sorption medium consists of recycled and natural materials that provide a favorable environment for pollutant removal. Water enters the system through the skimmer, which floats on the surface of the detention pond. It travels from the skimmer to the bottom of the chamber where heavier particles settle out before entering the upflow filter. The upflow filter contains 61 cm (24 in.) of green sorption medium providing physicochemical and microbiological processes to remove nitrogen and phosphorus under anoxic/anaerobic conditions. After this treatment, water flows up through the filter and out of the system and eventually travels to Lake Jesup, a eutrophic lake in Central Florida. A total of 28 storm events and seven baseflows were sampled from the site in Seminole County, and ten storm events were sampled from a pilot study of CUFS for statistical analysis and performance evaluation. Significant reductions by the CUFS were confirmed in terms of turbidity, orthophosphorus, total phosphorus, and total suspended solids when the mean values were compared at a 95% confidence level. Reductions also occurred for total nitrogen (TN), but could not be proved by the mean comparison in the field test, whereas the pilot-scale application of the CUFS proved effective for reducing TN at a 95% confidence level. Hydraulic retention time should be increased so as to improve the design for TN removal in future applications.     

Differences in the Rhizosphere Microbial Activity and Community Composition of Commelina communis along a Copper Contamination Gradient

We studied the effects of copper (Cu) phytoremediation on microbial community composition under laboratory conditions. A Cu accumulator, Commelina communis, was grown on a soil containing different gradients of Cu. Results showed that the biomass of C. communis grown with Cu differed from that of the control. Concentrations of Cu in the shoots of C. communis were 73.6, 160.9, and 319.1 mg kg^?1 under 200, 500, and 1000 mg kg^?1 Cu treatments, respectively. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprint analysis revealed that additions of Cu decreased the number of bands in the soil with C. communis or without plants. The principal component analysis explained 52.7% of the variance for the different rhizospheres of soil and Cu treatments in the soil samples. These results indicated significant effects on soil bacteria activity and community composition in the rhizosphere of C. communis and provided a basis for further studies of metal-accumulator plant effects on soil microorganisms.     

Toxicity of Uranium to Microbial Communities in Anaerobic Biofilms

Microbial processes have shown promise for the remediation of uranium and nitrate in groundwater impacted by uranium mine tailings. This study investigated the inhibitory impact of uranium(VI) towards different microbial populations in anaerobic biofilms, including methanogenic, denitrifying, and uranium-reducing microorganisms, which are commonly found at uranium bioremediation sites. Results of batch activity bioassays indicated a very distinct level of toxicity depending on the targeted microbial community. U(VI) caused severe inhibition of acetoclastic methanogenesis as indicated by a 50?% inhibiting concentration (IC₅₀) of only 0.16?mM. Denitrifying populations were also impacted by uranium, but their sensitivity depended on the electron donor utilized. Sulfur-oxidizing denitrifiers were the least affected (IC₅₀ for denitrification activity?=?0.32?mM), followed by H₂- and acetate-utilizing denitrifiers (IC₅₀ of 0.20 and 0.15?mM, respectively). In contrast, exposure to U(VI) concentrations up to 1.0?mM did not inhibit the rate of U(VI) bioreduction with H₂ as electron donor in the presence or absence of nitrate. On the contrary, a considerable increase in the uranium-reducing activity of the denitrifying and methanogenic mixed cultures was observed with increasing uranium concentrations. The results suggest that microorganisms responsible for U(V) reduction could tolerate much higher uranium concentrations compared to the other microbial populations assayed.     

Changes in the Past Soil-Forming Conditions and Human Activity in Soil Biological Memory: Microbial and Enzyme Components

Eurasian Soil Science - The concept of biological memory of soils and cultural layers is developed. This term is understood as information about soil-forming conditions of the past that is carried...     

原料差异对厌氧消化微生物群落的影响

以餐厨垃圾、果蔬垃圾、麦秸3种不同原料分别进行厌氧消化,研究了各反应器在最佳运行条件下的消化特性和微生物群落组成。结果表明：VS产气率由高到低依次为餐厨垃圾（756.4mL·g-1VS-1）、麦秸（696.5mL·g-1VS-1）和果蔬垃圾（433.5mL·g-1VS-1）,甲烷含量在51.5%～55.1%之间,利用PCR-DGGE技术系统地分析了不同原料消化系统内细菌和古菌的群落结构构成及差异。结果表明,虽然3组样品中细菌和古菌的群落存在相同的优势微生物,但其数量和群落结构差异也较为明显,细菌中以拟杆菌（Bacteroidetes）以及古菌中甲烷鬃菌属（Methanosaeta）和甲烷螺菌属（Methanospirillum）均为样品共有的优势微生物。     

Microbial Sulfate Reduction and Biogeochemistry of Arsenic and Chromium Oxyanions in Anaerobic Bioreactors

A pilot-scale anaerobic bioreactor with high levels of microbial sulfate reduction, known to be capable of removing cationic metals from a metal- and acid-contaminated waste stream, was utilized to determine if the system would be effective in removing metals in the form of oxyanions such as arsenate and chromate. The system removed 90 % to >99 % of the arsenic and between 86 % and 94 % of the chromium from a waste stream containing 5 mg/L of each. Cadmium, copper, iron, lead, and zinc also were removed. An equilibrium geochemistry computer modeling code, MINTEQAK, modified from MINTEQA2, was used for the chemical modeling of processes in the bioreactor. Experimental evidence on the chemical and biological reduction of arsenic and chromium and fluorescent diffraction analysis of precipitates support the following hypotheses: the primary removal process for chromium was the reduction of Cr(VI) to Cr(III) by sulfides, followed by precipitation of chromium hydroxide [Cr(OH)_3(s)]; removal of arsenic was by direct microbial enzymatic reduction of As(V) to As(III) followed by precipitation of arsenic sulfides (As₂S₃ or AsS). Experimental evidence and modeling with MINTEQAK confirmed that 90 % to 95 % of the removal of arsenic and chromium occurred in the first quarter volume of the bioreactor. Additional removal of arsenic and chromium occurred in the remaining volume of the bioreactor. The use of a sulfate reduction-based anaerobic treatment system was effective for metal-laden wastewater with elevated concentrations of arsenic and chromium.     

酞酸酯污染土壤微生物效应与过氧化氢酶活性的变化特征

采用室内模拟污染土壤,研究了邻苯二甲酸二(乙基-己基)酯和邻苯二甲酸二丁酯两种酞酸酯类化合物对农田土壤微生物生物量碳、土壤基础呼吸与土壤过氧化氢酶活性及其反应动力学参数的影响。结果表明,DBP土壤浓度在10 mg/kg,DEHP土壤浓度在20 mg/kg以下,与对照相比,微生物生物量碳、土壤基础呼吸以及过氧化氢酶活性没有明显影响。土壤浓度为20 mg/kg的DBP处理对土壤基础呼吸有明显的激活作用。两种化合物在高浓度处理的土壤中,均对微生物生物量碳、土壤基础呼吸以及过氧化氢酶活性表现抑制效应,抑制作用随处理浓度的增加而加强,其中两种化合物土壤浓度为100 mg/kg时,在培养期内三者均没有表现出明显的恢复趋势。对过氧化氢酶Km与Vmax以及Vmax/Km等动力学参数分析表明,DBP与DEHP没有对过氧化氢酶促反应速率以及酶与底物亲和力产生明显影响。     

松嫩平原盐碱化草原土壤理化特性及微生物结构分析

以松嫩平原不同程度的典型盐碱化草地及对照土壤为研究对象,考察了土壤的电导率、离子组成、碳素特征及微生物构成等,分析了盐碱地的理化特点及变化规律,并对该地区的盐碱化土壤的分类进行了深入探讨。结果表明,3个区域土壤的理化特征和微生物构成各有其特点,土壤的盐碱化过程伴随着土壤结构和微生物群落的变化;松嫩平原草地是个脆弱的生态系统,必须加强对它的保护和管理。     

猪场废水生化处理工艺研究

针对猪场废水有机物、氮、磷含量高的特征，应用上流式厌氧污泥床(UASB)和序批处理反应器(SBR)相结合废水处理工艺，研究了不同水力负荷条件下对COD、BOD、氨氮去除率的影响。研究结果表明，在COD 2～8 kg/(m³·d)条件下，COD的去除率在60%～73%之间，效果较稳定；SBR在去除氨氮中效果十分明显，去除率达80%～95%。     

Changes in Microbial Functional Diversity and Activity in Paddy Soils Irrigated with Industrial Wastewaters in Bandung, West Java Province, Indonesia

Characteristics, such as microbial biomass, basal respiration, and functional diversity of the microbial communities, were investigated in paddy soils located in Bandung, West Java Province, Indonesia, that have been heavily polluted by industrial effluents for 31 years. Paddy soil samples (10?C20 cm) were taken from two sites: polluted soils and unpolluted soils (as control sites). The polluted soils contained higher salinity, higher sodicity, higher nutrient contents, and elevated levels of heavy metals (Cr, Mn, Ni, Cu, and Zn) than unpolluted soils. Soil physicochemical properties, such as maximum water holding capacity, exchangeable sodium percentage, sodium adsorption ratio, and swelling factor, in polluted soils were much greater than those in unpolluted soils (P?<?0.05). Changes in the physical and chemical soil properties were reflected by changes in the microbial communities and their activities. BIOLOG analysis indicated that the functional diversity of the microbial community of polluted soils increased and differed from that of unpolluted soils. Likewise, the average rate of color development (average well color development), microbial biomass (measured as DNA concentration), and the soil CO₂ respiration were higher in polluted soils. These results indicate that major changes in the chemical and physical properties of paddy soils following the application of industrial wastewater effluents have had lasting impacts on the microbial communities of these soils. Thus, the increased activity, biomass, and functional diversity of the microbial communities in polluted soils with elevated salinity, sodicity, and heavy metal contents may be a key factor in enhancing the bioremediation process of these heavily polluted paddy soils.     

Aerobic versus Anaerobic Microbial Degradation of Etofenprox in a California rice field soil

The microbial degradation of etofenprox, an ether pyrethroid, was characterized under anaerobic (flooded) and aerobic (nonflooded) California rice field soil conditions by determination of its half-life (t1/2) and dissipation rate constant (k) and identification and quantification of degradation products at both 22 and 40 °C using LC-MS/MS. The overall anaerobic t1/2 at 22 °C ranged from 49.1 to 100 days (k=-0.0141 to -0.0069 days(-1)) compared to 27.0 days (k=-0.0257 days(-1)) at 40 °C, whereas under aerobic conditions the overall t1/2 was 27.5 days (k=-0.0252 days(-1)) at 22 °C compared to 10.1-26.5 days (k=-0.0686 to -0.0262 days(-1)) at 40 °C. The biphasic dissipation profiles were also fit to a first-order model to determine the t1/2 and k for both the fast and slow kinetic regions of the dissipation curves. Hydroxylation at the 4'-position of the phenoxy phenyl ring was the major metabolic process under anaerobic conditions for both 22 °C (maximum% yield of applied etofenprox mass=1.3±0.7%) and 40 °C (max % yield=1.2±0.8%). Oxidation of the ether moiety to the ester was the major metabolite under aerobic conditions at 22 °C (max% yield=0.5±0.1%), but at 40 °C increased amounts of the hydroxylated form were produced (max% yield=0.7±0.2%, compared to 0.3±0.1% for the ester). The hydrolytic product of the ester, 3-phenoxybenzoic acid (3-PBA), was not detected in any samples. Sterilized control soils showed little etofenprox degradation over the 56-day incubation period. Thus, the microbial population in a flooded soil was able to transform and contribute to the overall dissipation of etofenprox. The simulated summer temperature extreme (40 °C) increased the overall degradation.     

Effect of Soil Drying Intensity During an Experimental Drying-Rewetting Event on Nutrient Transformation and Microbial Community Composition

Soil drying-rewetting(DRW) events affect nutrient transformation and microbial community composition; however, little is known about the influence of drying intensity during the DRW events. Therefore, we analyzed soil nutrient composition and microbial communities with exposure to various drying intensities during an experimental drying-rewetting event, using a silt loam from a grassland of northern China, where the semi-arid climate exposes soils to a wide range of moisture conditions, and grasslands account for over 40% of the nation's land area. We also conducted a sterilization experiment to examine the contribution of soil microbes to nutrient pulses. Soil drying-rewetting decreased carbon(C) mineralization by 9%–27%. Both monosaccharide and mineral nitrogen(N) contents increased with higher drying intensities(drying to ≤ 10% gravimetric water content), with the increases being 204% and 110% with the highest drying intensity(drying to 2% gravimetric water content), respectively, whereas labile phosphorus(P)only increased(by 105%) with the highest drying intensity. Moreover, levels of microbial biomass C and N and dissolved organic N decreased with increasing drying intensity and were correlated with increases in dissolved organic C and mineral N, respectively,whereas the increases in labile P were not consistent with reductions in microbial biomass P. The sterilization experiment results indicated that microbes were primarily responsible for the C and N pulses, whereas non-microbial factors were the main contributors to the labile P pulses. Phospholipid fatty acid analysis indicated that soil microbes were highly resistant to drying-rewetting events and that drought-resistant groups were probably responsible for nutrient transformation. Therefore, the present study demonstrated that moderate soil drying during drying-rewetting events could improve the mineralization of N, but not P, and that different mechanisms were responsible for the C, N, and P pulses observed during drying-rewetting events.     

Response of Soil Microbial Biomass and Enzyme Activity to Soil Fertilization in an Eroded Farmland of Chinese Mollisols

The aims of this study were to examine interrelationships between microbial biomass and enzyme activities of soil quality and to determine their suitability for differentiating areas. The study included five simulated erosion soil depths (0, 5, 10, 20, and 30 cm), which had received contrasting fertilizer treatments over a 5-year period in an eroded black soil of northeastern China. Our results indicated that soil microbial carbon, nitrogen, urease, phosphatase, and invertase activities declined as the erosion depth increased. On the five erosion depths, soil microbial carbon, phosphatase, and invertase variation ranged as follows: 35.4–53.3, 39.8–45.2, and 55.9–67.1%, respectively. In the fertilizer + manure treatment, soil microbial carbon, nitrogen, urease, phosphatase, and invertase activities were significantly greater (P < 0.05) than those of fertilizer treatment in all five different erosion depths. Overall, this study may be considered as the foundation for soil quality evaluation and fertility restoration in northeastern China and similar regions.     

设施土壤微生物学特性变化研究

采用定点取样的方法，研究了不同种植年限设施土壤微生物主要类群、生物量碳和5种酶活性的变化特点，结果表明：（1）不同种植年限设施土壤微生物主要类群随季节变化不一致，细菌数量先升后降，高峰出现在6月，10月最低；真菌和放线菌数量均在3月最多，而后逐渐减少。随设施种植年限的延长，微生物总数逐渐增加，但真菌和放线菌占微生物总数的比例却呈下降趋势。与露地相比，设施栽培中真菌增加快于细菌。（2）不同种植年限设施土壤微生物生物量碳在3月和6月含量最高，随设施种植年限的延长，微生物生物量碳含量也增加。（3）不同种植年限设施土壤酶活性季节变化明显，除过氧化氢酶外，脲酶、酸性磷酸酶、中性磷酸酶和转化酶活性高峰主要出现在3月，土壤酶的总体活性随设施种植年限的延长有所下降。     

Anaerobic Dechlorination of Tetrachlorobisphenol A in River Sediment and Associated Changes in Bacterial Communities

Tetrachlorobisphenol A (TCBPA) is a widely used flame retardant and a potential endocrine disruptor. We estimated the role of the microbial community in degradation of TCBPA in river sediment from the vicinity of an E-waste processing facility. The effects of different anaerobic conditions on degradation efficiency of TCBPA were investigated, and differences in bacterial communities among these conditions were analyzed by 16S ribosomal RNA (rRNA) gene sequencing. The most effective dechlorination of TCBPA occurred under methanogenic conditions followed by electron donor-enhanced conditions and sulfate-reducing conditions with initial sulfate concentrations of 1, 10, and 20 mM. The extent of TCBPA removal under these conditions mentioned above was 65, 44, 43, 23, and 23%, respectively. 16S rRNA gene sequence analysis indicated that five dominant genera in the phylum Chloroflexi and another five species of Bacteroidetes, Chlorobi, and Firmicutes in these five systems were largely involved in TCBPA dechlorination. The initial sample had a total relative abundance of autochtonous potential dechlorinating bacteria of 12%. After 160 days, these values increased to 29–43% under above conditions. Addition of TCBPA decreased bacterial diversity. Efficiency of TCBPA degradation depends on the abundance and metabolism of dechlorinating bacterial guilds. The effectiveness of dechlorinating microbes in degradation of TCBPA was reduced by high sulfate concentrations.     

混交林地土壤物理性质与微生物数量及酶活性的研究

研究了枫香×樟树、楠木×尖叶杜英、木周木×海南红豆、格木×海南红豆、火力楠×阴香、枫香×米老排×降香黄檀、樟树×马占相思混交林林地的土壤物理性质与微生物数量及酶活性。各林地的容重、毛管孔隙、非毛管孔隙、自然含水量、毛管持水量的不同引起其保水性和通气性的差异。细菌是土壤微生物总量的主要组成者。各混交林地的细菌、真菌和放线菌的数量差异大。各混交林地的脲酶、过氧化氢酶和纤维素分解酶活性有一定的差异。放线菌与容重呈显著正相关,而与总孔隙呈显著负相关。脲酶与自然含水量、毛管持水量、毛管孔隙呈显著或极显著正相关。