Search

The removal of EDCs in activated sludge processes can be enhanced by increasing solid and hydraulic retention times (SRT and HRT); it has been suggested that the improvement in removal is due to changes in microbial community structure (MCS). Though the influence of SRT and HRT on chemical removal and MCS has been studied in isolation, their synergistic impact on MCS and the removal of estrogens and nonylphenols in activated sludge remains unknown. Hence, we investigated how both parameters influence MCS in activated sludge processes and their ulterior effect on EDC removal. In our study, an activated sludge pilot-plant was fed with domestic sewage fortified with 100 and 1000 ng/L nonylphenols or 2 and 15 ng/L estrogens and operated at 3, 10 and 27 d SRT (constant HRT) and at 8, 16 and 24 h HRT (constant SRT). The MCS was assessed by phospholipid fatty acids (PLFA) analysis, and the archaeal and bacterial diversities were determined by 16S rRNA analysis. From the PLFA, the microbial abundance ranked as follows: Gram-negative > fungi > Gram-positive > actinomycetes whilst 16S rRNA analysis revealed Proteobacteria > Bacteroidetes > Others. Both PLFA and 16S rRNA analysis detected changes in MCS as SRT and HRT were increased. An SRT increment from 3 to 10 d resulted in higher estrone (E1) removal from 19 to 93% and nonylphenol-4-exthoxylate (NP4EO) from 44 to 73%. These findings demonstrate that EDC-removal in activated sludge plants can be optimised where longer SRT (>10 d) and HRT (>8 h) are suitable. We have also demonstrated that PLFA can be used for routine monitoring of changes in MCS in activated sludge plants.

Both soil organic carbon (SOC) and soil inorganic carbon (SIC) are important carbon reservoirs involved in the global carbon cycle. Fertilization especially organic amendments can increase SOC sequestration, while nitrogen fertilization‐induced soil acidification leads to significant SIC loss in alkline soil. How fertilization changes SIC and SOC via altering abiotic and biotic properties remains unclear. Here, we investigated the effects of mineral fertilizer with/without organic amendments (manure, straw, green manure) on SIC and SOC in bulk soil and particle‐size fractions, as well as their interrelationship based on a 38‐year field trial. Results showed that compared to the unfertilized soil, mineral fertilization significantly decreased SIC by 13.38%–15.69%, primarily due to decreased soil pH. However, mineral nitrogen plus manure (NM) largely increased SIC by 26.55%, likely resulting from the CO32− reprecipitated by Ca2+ and/or Mg2+ compensation. Mineral nitrogen plus manure and straw (NM, NS) increased SOC by 11.12%–100.35%. For bulk soil and particle‐size fractions >0.25 mm, SIC content was positively correlated with SOC. Random forest model revealed that SOC was regulated by soil nutrients (total nitrogen [TN], Olsen‐P), microbial biomass and β‐1,4‐N‐acetyl‐glucosaminidase. The change in SIC was directly regulated by soil Mg2+, and indirectly by soil nutrients (e.g., TN, Olsen‐P) which affected crop‐derived C input. Our findings suggested that organic manure amendments can facilitate SOC accumulation and mitigate SIC loss by occluded more SIC in large soil particles. The results are of fundamental significance for understanding the role of optimal manure application played in SOC sequestration and SIC accumulation. [ABSTRACT FROM AUTHOR]

Climate change is predicted to alter global precipitation regimes. However, the response of soil carbon and nitrogen cycles and soil microorganisms to precipitation reduction is poorly understood but is dependent on ecosystem type. To evaluate the impacts of reduced precipitation on soil respiration, soil inorganic nitrogen (i.e., NH4+–N and NO3−–N), nitrogen mineralization, and soil microbial community composition, a precipitation manipulation experiment was initiated in a Mongolian pine plantation and a naturally restored grassland in semi-arid northeast China. Precipitation reduction led to decreases of soil respiration rates by 14 and 8% in 2014 and 2015 in the Mongolian pine plantation but no changes in the grassland. Soil inorganic nitrogen, ammonification and nitrification rate, and soil phospholipids fatty acids were not significantly changed by reduced precipitation but significantly differed between the two ecosystems and among growing seasons. Our results suggest that the impacts of precipitation reduction on soil respiration were different between the Mongolian pine plantation and the grassland, and that ecosystem type and growing season had more pronounced impacts on soil carbon and nitrogen cycles. [ABSTRACT FROM AUTHOR]

Soil water repellency (SWR) can influence many hydrological soil properties, including water infiltration, uneven moisture distribution or water retention. In the current study we investigated how variable SWR persistence in the field is related to the soil microbial community under different plant species (P. halepensis, Q. rotundifolia, C. albidus and R. officinalis) in a Mediterranean forest. The soil microbial community was determined through phospholipid fatty acids (PLFA). The relationships between microbiological community structure and the soil properties pH, Glomalin Related Soil Protein (GRSP) and soil organic matter (SOM) content were also studied. Different statistical analyses were used: Principal Component Analysis (PCA), ANOVA, Redundancy Analysis and Pearson correlations. The highest concentrations of PLFA were found in the most water repellent samples. PCA showed that microorganism composition was more dependent of the severity of SWR than the type of plant species. In the Redundancy Analysis, SWR was the only significant factor (p

The removal of EDCs in activated sludge processes can be enhanced by increasing solid and hydraulic retention times (SRT and HRT); it has been suggested that the improvement in removal is due to changes in microbial community structure (MCS). Though the influence of SRT and HRT on chemical removal and MCS has been studied in isolation, their synergistic impact on MCS and the removal of estrogens and nonylphenols in activated sludge remains unknown. Hence, we investigated how both parameters influence MCS in activated sludge processes and their ulterior effect on EDC removal. In our study, an activated sludge pilot-plant was fed with domestic sewage fortified with 100 and 1000 ng/L nonylphenols or 2 and 15 ng/L estrogens and operated at 3, 10 and 27 d SRT (constant HRT) and at 8, 16 and 24 h HRT (constant SRT). The MCS was assessed by phospholipid fatty acids (PLFA) analysis, and the archaeal and bacterial diversities were determined by 16S rRNA analysis. From the PLFA, the microbial abundance ranked as follows: Gram-negative > fungi > Gram-positive > actinomycetes whilst 16S rRNA analysis revealed Proteobacteria  >  Bacteroidetes  > Others. Both PLFA and 16S rRNA analysis detected changes in MCS as SRT and HRT were increased. An SRT increment from 3 to 10 d resulted in higher estrone (E1) removal from 19 to 93% and nonylphenol-4-exthoxylate (NP 4 EO) from 44 to 73%. These findings demonstrate that EDC-removal in activated sludge plants can be optimised where longer SRT (>10 d) and HRT (>8 h) are suitable. We have also demonstrated that PLFA can be used for routine monitoring of changes in MCS in activated sludge plants., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

Phospholipids fatty acids (PLFAs) in sewage sludge were analyzed to evaluate the variation in the microbial communities during 100 d composting. Pumice was used as an inorganic bulking agent to eliminate the influences of conventional organic materials on the PLFAs analysis result of the sludge. The results showed that the maximal PLFAs content of 407.41 μg g−1VS was presented on Day-10 and the minimal PLFAs content of 207.49 μg g−1VS was detected on Day-100. Bacteria and fungi were mainly the micro-organisms in the thermophilic stage. The number of bacteria distinctly reduced during the curing stage, whereas the abundances of gram-positive bacteria (14:0 iso, 16:0 iso, 17:0 anteiso), pseudomona (18:1ω7c), actinobacteria (18:0 10-methyl), and fungi (18:3ω6c (6, 9, 12)) tended to increase simultaneously. Protozoa were detected in the raw sludge and the matured sample, but not presented within the theromophilic period. Culture-dependent method was introduced to verify the results of microbial populations. The numbers of bacteria and fungi reached maximum (3.38 × 1012and 3.31 × 109 CFU g−1 d s, respectively) on Day-10 and then reduced. The number of actinomycetes increased gradually and reached 3.24 × 107 CFU g−1 d s, on Day-100. The results indicated that PLFAs technique is an efficient and convenient method to investigate the variation in the microbial communities during sewage sludge composting. [ABSTRACT FROM AUTHOR]

The phospholipid fatty acid (PLFA pattern) and community level physiological profiling (CLPP) techniques were simultaneously used to evaluate the short- and medium-term effects produced by an experimental fire and two different stabilization treatments on the soil microbial communities. The study was performed in a scrubland ecosystem located in Galicia (N.W. of Spain). The measurements were made in soil samples collected from the top layer (0–5 cm) immediately and 90, 180 and 365 days after the fire and application of seeding and mulching treatments. Regardless of the technique used (PLFA, CLPP), the results indicated that the experimental fire caused marked changes in the soil microbial community, which persisted even 1 year after the fire, whereas the post-fire treatments induced no changes or slight changes on the microorganisms of this burned soil. In addition, a significant effect of the sampling time on the functional diversity and the soil microbial community structure, particularly on the latter, was observed. The relative importance of the two main factors (experimental fire and intra-annual variation) in determining the microbial community composition of the studied soils varied notably depending on the technique used; the experimental fire had a greater impact on the functional diversity (as evidenced by CLPP) than on the microbial community structure (as evidenced by PLFA). The results support the convenience of using both methodological approaches (PLFA pattern and CLPP) to gain more insight into the microbial communities of this degraded burned soil. [ABSTRACT FROM AUTHOR]

The degradation of polycyclic aromatic hydrocarbons (PAHs) including fluorene, phenanthrene, anthracene, fluoranthene and pyrene were investigated under thermophilic and mesophilic anaerobic-methanogenic conditions. By using central composite design, the impact of PAH concentration and soil to inocula ratio were systematically studied for their influence on PAH removal and biogas production. During the first 30 days, PAH concentration decreased in all samples indicating that the inocula used were able to biodegrade the contaminants; although an inhibition effect was initially observed in biogas production. Phospholipids fatty acids analysis was used to monitor the microbial communities present during the process. These communities were more complex in samples containing moderate to high PAH contamination concentrations. After 50 days, the concentration of PAHs increased in the majority of samples indicating possible reversed biotransformation of these compounds. [ABSTRACT FROM AUTHOR]

Cupriavidus metallidurans CH34 and Pseudomonas putida mt2 were used as cadmium (Cd) resistant and sensitive bacteria, respectively to study the effect of Cd on physicochemical surface properties which include the study of surface charge and hydrophobicity which are subjected to vary under stress conditions. In this research work, effective concentration 50 (EC50) was calculated to exclude the doubt that dead cells were also responding and used as reference point to study the changes in cell surface properties in the presence of Cd. EC50 of C. metallidurans CH34 was found to be 2.5 and 0.25 mM for P. putida mt2. The zeta potential analysis showed that CH34 cells were slightly less unstable than mt2 cells as CH34 cells exhibited −8.5 mV more negative potential than mt2 cells in the presence of Cd in growth medium. Cd made P. putida mt2 surface to behave as intermediate hydrophilic ( θw = 25.32°) while C. metallidurans CH34 as hydrophobic ( θw = 57.26°) at their respective EC50. Although belonging to the same gram-negative group, both bacteria behaved differently in terms of changes in membrane fluidity. Expression of trans fatty acids was observed in mt2 strain (0.45%) but not in CH34 strain (0%). Similarly, cyclopropane fatty acids were observed more in mt2 strain (0.06-0.14%) but less in CH34 strain (0.01-0.02%). Degree of saturation of fatty acids decreased in P. putida mt2 (36.8-33.75%) while increased in C. metallidurans CH34 (35.6-39.3%). Homeoviscous adaptation is a survival strategy in harsh environments which includes expression of trans fatty acids and cyclo fatty acids in addition to altered degree of saturation. Different bacteria show different approaches to homeoviscous adaptation. [ABSTRACT FROM AUTHOR]

Abstract: In Eastern Spain, almond trees have been cultivated in terraced orchards for centuries, forming an integral part of the Mediterranean forest scene. In the last decades, orchards have been abandoned due to changes in society. This study investigates effects of changes in land use from forest to agricultural land and the posterior land abandonment on soil microbial community, and the influence of soil physico-chemical properties on the microbial community composition (assessed as abundances of phospholipids fatty acids, PLFA). For this purpose, three land uses (forest, agricultural and abandoned agricultural) at four locations in SE Spain were selected. Multivariate analysis showed a substantial level of differentiation in microbial community structure according to land use. The microbial communities of forest soils were highly associated with soil organic matter content. However, we have not found any physical or chemical soil property capable of explaining the differences between agricultural and abandoned agricultural soils. Thus, it was suggested that the cessation of the perturbation caused by agriculture and shifts in vegetation may have led to changes in the microbial community structure. PLFAs indicative of fungi and ratio of fungal to bacterial PLFAs were higher in abandoned agricultural soils, whereas the relative abundance of bacteria was higher in agricultural soils. Actinomycetes were generally lower in abandoned agricultural soils, while the proportions of vesicular–arbuscular mycorrhyzal fungi were, as a general trend, higher in agricultural and abandoned agricultural soils than in forests. Total microbial biomass and richness increased as agricultural

Dietary fat and its relation to obesity has been a controversial issue for many years. Experimental data shows that most, though not all animals, which consume a high fat diet, will become obese. However, the effect of fatty acids on animal obesity has not been studied in detail. In order to evaluate the effects of low versus high fat diet on serum phospholipids fatty acids composition a 4-wk study was conducted on male Wister rats. The rats were fed low-fat (10% energy) and high-fat (46% energy) foods containing constant proportions of fatty acids. Control group C was fed a standard laboratory diet (polyunsaturated/ saturated (P/S) fatty ratio 1.3), group M was fed a standard laboratory diet supplemented with margarine (P/S ratio 0.95), and the diet of the SL group was additionally supplemented with a sunflower oil-lard (1:1) mixture (P/S ratio 1.3). All lipid supplemented hyperenergetic diets caused an increase in the average daily energy intake. Both the final and the daily body weight gain were significantly higher in M and SL groups than in group C. Additionally, serum triglyceride levels, LDL-cholesterol and total cholesterol were also significantly higher in M and SL groups when compared to the control group. Serum phospholipids fatty acids varied in response to total dietary fat. A significant decrease in saturated fatty acids (SFA) content (16:0 and 18:0) and an increase in monounsaturated fatty acid (MUFA) content (18:1, n-9) was found in the Mgroup when compared to both C and SL groups. In the SL group, SFA content (18:0) was higher and MUFA content (18:1, n-9) was lower than in group C. Polyunsaturated fatty acids (PUFA) content showed an increase in both experimental groups. The PUFA/SFA ratio was higher in the M group than in the C and SL groups. Our study suggests that the amount of dietary fat has a greater influence on obesity than the effects of the type of fat consumed. However, depending on the type of fat present in the diet the differences were observed in the composition of serum PL fatty acid suggesting that both total fat and individual fatty acids have to be considered when reaching conclusions about the effect of dietary fat and obesity in animals. [ABSTRACT FROM AUTHOR]