Microbial Biomass,P-Nutrition,and Enzymatic Activities of Wheat Soil in Response to Phosphorus Enriched Organic and Inorganic Manures

Compost was prepared from wheat straw enriched with Rajasthan rock phosphate and Aspergillus awamori. The resulting phospho-compost along with phosphorus enriched FYM, mineral fertilizer (rock phosphate) and super phosphate were evaluated for their individual contribution in improving organic matter status, P availability, and enzymatic activities of soil under wheat crop grown in a micro plot. The results showed that total organic carbon, nitrogen, microbial biomass, and humus content (an index of organic matter status of soil) of soil was highest when farmyard manure (FYM) after its enrichment with 12.5% rock phosphate was applied. Microbial enriched phospho-compost was the product yielding highest soil available phosphorus, phosphorus uptake, urease, and cellulase activities. However, FYM amended with 25% rock phosphate resulted in the greatest enhancement of β-glucosidase. Measured parameters indicated a sure improvement of chemical and biological activities of soil after the application of phosphorus enriched organic amendments compared to the commercial fertilizer commonly used by the Indian farmers.     

Effects of petroleum contamination on soil microbial numbers, metabolic activity and urease activity

The influence of petroleum contamination on soil microbial activities was investigated in 13 soil samples from sites around an injection water well (Iw-1, 2, 3, 4) (total petroleum hydrocarbons (TPH): 7.5-78 mg kg⁻¹), an oil production well (Op-1, 2, 3, 4, 5) (TPH: 149-1110 mg kg⁻¹), and an oil spill accident well (Os-1, 2, 3, 4) (TPH: 4500-34 600 mg kg⁻¹). The growth rate constant (μ) of glucose stimulated organisms, determined by microcalorimetry, was higher in Iw soil samples than in Op and Os samples. Total cultivable bacteria and fungi and urease activity also decreased with increasing concentration of TPH. Total heat produced demonstrated that TPH at concentrations less than about 1 g kg⁻¹ soil stimulated anaerobic respiration. A positive correlation between TPH and soil organic matter (OM) and stimulation of fungi-bacteria-urease at low TPH doses suggested that TPH is bound to soil OM and slowly metabolized in Iw soils during OM consumption. These methods can be used to evaluate the potential of polluted soils to carry out self-bioremediation by metabolizing TPH.     

Effects of sludge age on anaerobic acidification of waste activated sludge: Volatile fatty acids production and phosphorus release

Effects of sludge age on volatile fatty acids (VFAs) production and Phosphorus (P) release during anaerobic acidification of waste activated sludge (WAS) were investigated. Sequencing batch reactors (SBR) fed with simulating domestic sewage were applied to produce WAS of different sludge ages, and batch tests were used for anaerobic acidification. The maximum dissolved total organic carbon, release of  ${\text{PO}}_4^{3+}?\mathrm{P}$, and accumulation of acetate (C2), propionate (C3), butyrate (C4), and valerate (C5) decreased by 56.2%, 55.8%, 52.6%, 43.7%, 82.4% and 84.8%, respectively, as the sludge age of WAS increased from 5 to 40 days. Limited degradation of protein played a dominating role in decreasing DTOC and VFAs production. Moreover, the increase in molecular weight of organics and organic nitrogen content in the supernatant after acidification suggested that the refractory protein in WAS increased as sludge age extended. Although the production of C2, C3, C4, and C5 from WAS decreased as the sludge age increased, the proportions of C2 and C3 in VFAs increased, which might be due to the declined production of C5 from protein and the faded genus Dechlorobacter. Keeping sludge age of WAS at a relatively low level (<10 days) is more appropriate for anaerobic acidification of WAS as internal carbon sources and P resource.     

RAPD Marker and Substrate Utilization Pattern Applied to Study Microbial Community Diversity in the Soil Affected by Agricultural Chemicals

Abstract

Present analyses of random amplified polymorphic DNA (RAPD) and Biolog GN substrate utilization pattern are combined to further study the diversity of microbial communities in four soils affected by agricultural chemicals. The results showed that the four soil microbial communities were apparently distinguishable in the diversity at RAPD level in terms of the richness and modified richness in the summer, which supports our previous report using the same soils in winter. A significant difference for the average well color development (AWCD) at 72 h incubation was found among the soils in winter using Biolog GN substrate utilization pattern, but this difference was not found among the soils in summer. However, Shannon-Weaver indices for microbial communities in the summer soils polluted by agricultural chemicals were significantly higher than those in winter at metabolic level; in contrast, no significant difference existed between the two seasons for microbial communities in the soil without chemical pollution. Present results suggest that the combined approach using RAPD and substrate utilization pattern could be used to effectively quantify microbial community diversity and its changes among the seasons in the soils affected by agricultural chemicals, simultaneously at molecular and physiological levels.     

Rhizobacteria helps to explain the enhanced efficiency of phytoextraction strengthened by Streptomyces pactum

The ultimate purpose of phytoextraction is not only to remove heavy metals from soil but also to improve soil quality. Here, we evaluated how the joint effect of Streptomyces pactum (strain Act12) and inorganic (Hoagland's solution) and organic (humic acid and peat) nutrients affected the phytoextraction practice of cadmium (Cd) and zinc (Zn) by potherb mustard, and the microbial community composition within rhizosphere was also investigated. The results indicated that the nutrients exerted synergistically with Act12, all increasing the plant biomass and Cd/Zn uptakes. The inoculation of Act12 alone significantly increased dehydrogenase activity of rhizosphere soil (P < 0.05), while urease and alkaline phosphatase activities varied in different dosage of Act12. Combined application of microbial strain with nutrients increased enzymatic activities with the elevated dosage of Act12. 16S ribosomal RNA high-throughput sequencing analysis revealed that Act12 inoculation reduced the diversity of rhizosphere bacteria. The Act12 and nutrients did not change dominant phyla i.e., Proteobacteria, Bacteroidetes, Gemmatimonadetes, Actinobacteria and Acidobacteria, but their relative abundance differed among the treatments with: Peat > Act12 > Humic acid > Hoagland's solution. Comparatively, Sphingomonas replaced Thiobacillus as dominant genus after Act12 application. The increase in the Sphingomonas and Flavisolibacter abundances under Act12 and nutrients treatments gave rise to growth-promoting effect on plant. Our results revealed the important role for rhizosphere microbiota in mediating soil biochemical traits and plant growth, and our approach charted a path toward the development of Act12 combined with soil nutrients to enhance soil quality and phytoextraction efficiency in Cd/Zn-contaminated soils.     

微生物絮凝剂的现状与前景分析

综述了传统絮凝剂在水处理中存在的缺陷以及微生物絮凝剂在水处理中的优越性，对微生物絮凝剂可能在将来取代或部分取代传统的无机及有机高分子絮凝剂作了科学的分析，并针对现今微生物絮凝剂发展的不足指出了今后的发展趋势。     

Effect of 2-butenal manufacture wastewater to methanogenic activity and microbial community

The inhibition ratio sharply increased with the increasing COD. The absorbance of UV-vis at 420 nm showed a linear correlation with the SMA. The molecular structure of EPS has changed when COD was 9585 mg/L. Illumina Miseq sequencing was employed to reveal the microbial composition. The synthesis of 2-butenal, which is a vital raw material for the production of sorbic acid as a food preservative, generates some toxic by-products, so it is urgent to seek better detoxification strategies for the treatment of 2-butenal manufacture wastewater. In this study, batch experiments were carried out to investigate the inhibition effect of wastewater on the methanogenic activity. To understand the wastewater toxicity to anaerobic granular sludge, variations of the specific methanogenic activity (SMA) and extracellular polymeric substance (EPS) constituents at various wastewater CODs were investigated. Ultraviolet-visible (UV-vis) spectra and Fourier transform infrared (FT-IR) spectra were employed to analyze the structure of the EPS. The results showed that the inhibitory ratio of 2-butenal manufacture wastewater was less than 8.4% on the anaerobic granular sludge when the CODs were less than 959 mg/L. However, the inhibitory ratio increased from 36.4% to 93.6% when CODs increased from 2396 mg/L to 9585 mg/L, with the SMA decreasing from 39.1 mL CH₄/(gVSS·d) to 3.2 mL CH₄/(gVSS·d). The diversity of the microbial community under various CODs was researched by Illumina 16S rRNA Miseq sequencing and the results demonstrated that Proteiniphilum、Petrimonas and Syntrophobacter were the dominant bacteria genera in all sample. Regarding archaea, Methanobacterium was the most dominated archaea genera, followed by the Methanosaeta group in all samples. Moreover, the bacterial communities had changed obviously with increasing CODs, which indicated high CODs played a negative impact on the richness and diversity of bacterial community in the sludge samples.     

Direct and indirect effects of metal contamination on soil biota in a Zn-Pb post-mining and smelting area (S Poland)

Effects of metal contamination on soil biota activity were investigated at 43 sites in 5 different habitats (defined by substratum and vegetation type) in a post-mining area. Sites were characterised in terms of soil pH and texture, nutrient status, total and exchangeable metal concentrations, as well as plant species richness and cover, abundances of enchytraeids, nematodes and tardigrades, and microbial respiration and biomass. The concentrations of total trace metals were highest in soils developed on mining waste (metal-rich dolomite), but these habitats were more attractive than sandy sites for plants and soil biota because of their higher content of organic matter, clay and nutrients. Soil mesofauna and microbes were strongly dependent on natural habitat properties. Pollution (exchangeable Zn and Cd) negatively affected only enchytraeid density; due to a positive relationship between enchytraeids and microbes it indirectly reduced microbial activity.     

Improvement of soil quality after "alperujo" compost application to two contaminated soils characterised by differing heavy metal solubility

Reclamation of trace element polluted soils often requires the improvement of the soil quality by using appropriate organic amendments. Low quality compost from municipal solid waste has been tested for reclamation of soils, but these materials can provide high amounts of heavy metals. Therefore, a high-quality compost, with low levels of heavy metals, produced from the main by-product of the Spanish olive oil extraction industry ("alperujo") was evaluated for remediation of soils affected by a pyritic mine sludge. Two contaminated soils were selected from the same area: they were characterised by differing pH values (4.6 and 7.3) and total metal concentrations, which greatly affected the fractionation of the metals. Compost was applied to soil at two rates (equivalent to 48 and 72 Tm ha(-1)) and compared with an inorganic fertiliser treatment. Compost acted as an available nutrient source (C, N and P) and showed a low mineralisation rate, suggesting a slow release of nutrients and thus favouring long term soil fertility. In addition, the liming effect of the compost led to a significant reduction of toxicity for soil microorganisms in the acidic soil and immobilisation of soil heavy metals (especially Mn and Zn), resulting in a clear increase in both soil microbial biomass and nitrification. Such positive effects were clearly greater than those provoked by the mineral fertiliser even at the lowest compost application rate, which indicates that this type of compost can be very useful for bioremediation programmes (reclamation and revegetation of polluted soils) based on phytostabilisation strategies.     

Determination of growth kinetics of microorganisms linked with 1,4-dioxane degradation in a consortium based on two improved methods

● Evaluated three methods for determining the consortia’s growth kinetics. ● Conventional method is flawed since it relies on the total biomass concentration. ● Considering only selected bacterial taxa improved the accuracy. ● Considering oligotrophs and copiotrophs further improved the accuracy. The conventional method for determining growth kinetics of microbial consortia relies on the total biomass concentration. This may be inaccurate for substrates that are uncommon in nature and can only be degraded by a small portion of the microbial community. 1,4-dioxane, an emerging contaminant, is an example of such substrates. In this work, we evaluated an improved method for determining the growth kinetics of a 1,4-dioxane-degrading microbial consortium. In the improved method, we considered only bacterial taxa whose concentration increase correlated to 1,4-dioxane concentration decrease in duplicate microcosm tests. Using PEST (Parameter Estimation), a model-independent parameter estimator, the kinetic constants were estimated by fitting the Monod kinetics-based simulation results to the experimental data that consisted of the concentrations of 1,4-dioxane and the considered bacterial taxa. The estimated kinetic constants were evaluated by comparing the simulation results with experimental results from another set of microcosm tests. The evaluation was quantified by the sum of squared relative residual, which was four orders of magnitude lower for the improved method than the conventional method. By further dividing the considered bacterial taxa into oligotrophs and copiotrophs, the sum of squared relative residual further decreased.