Activity Of Microorganisms Research Articles

Biochar Enhanced Chemical and Biological Properties of Contaminated Soils with Lead

Soil pollution has become a global problem due to the significant increase in the concentration of heavy elements. Lead is one of the most dangerous heavy elements cause damages to soil microorganisms and soil chemical properties. In this study the effect of adding of biochar (EFBB and WSB) with different addition rates (0%, 1% and 3%) in two soil textures (sandy loam, clay loam) contaminated with lead (500 ppm) were studies to approve the role of biochars on some soil chemical properties of soils and microorganisms activity. The results showed the amount of released CO2 has increased up to (127.6 and 123.2 mg CO2 100 g-1 soil) with addition rate (3%) of WSB and EFBB compared to control treatments (45.4 mg CO2 100 g-1 soil). This result indicated that the microorganism’s activity was enhanced with incubation periods in contaminated soils. It was noted that biochars improved soil chemical properties such as OM, OC, CEC, cations of positive elements such as Ca2+, Mg2+, and K+ and improved electrical conductivity EC. A larger surface area and the negative charges content as well as micro pores are made biochars more effective to adsorbed heavy metals, which allows reducing toxicity of lead in contaminated soil and making its environment more suitable for microorganism’s life with enhancing some soil chemical properties. Therefore, it is recommended to add biochar to contaminated soils and it could be an alternative to other treatments due to its low-cost.

Novel kombucha beverages with antioxidant activity based on fruits as alternative substrates

The consumption of kombucha drinks has remarkably grown during the last decade and, besides traditional ingredients such as tea leaves, alternative raw materials with interesting functional properties are being proposed. The aim of this study was to obtain alternative kombuchas enriched in phenolic compounds and with a high antioxidant activity using fruits instead of tea leaves, and to determine the optimal fermentation time. The fruit-based kombuchas were prepared using cherry, plum, apricot, strawberry, persimmon, grape, orange, or pomegranate and three different microbial consortia (SCOBYs/SCs). The pH, carbohydrate, ethanol, and phenolic levels, and in vitro antioxidant capacity were determined along the fermentation process (21 days). The obtained products showed safe pH values (2.5–4.2) and suitable ethanol levels (<1.2%). Their carbohydrate content was almost half that in commercial tea kombucha. The activity of fermentative microorganisms increased total phenolic content (TPC) and radical scavenging capacity (TEAC) in all preparations, and differences were found depending on the SC used. Maximum TPC and TEAC values were observed in the strawberry kombucha (up to 13.7 mg/100 mL and 2.05 μmol/mL, respectively). The results showed that fruits, mainly strawberries, could be used to obtain alternative kombucha drinks with high in vitro antioxidant activity.

Impact of antibiotics on methane produced from cellulose

Enhancing production of methane from cellulose is of utmost importance to improve the fermentation efficiency of lignocellulosic biomass. Antibiotics have demonstrated their ability to stimulate anaerobic digestion (AD) by influencing micro-organism activity. However, there has been limited research on the specific effect of antibiotics on cellulose AD. In this study, we investigated the impact of three antibiotics—tetracycline (TC), cephalexin (CLX), and azithromycin (AZM)—on cellulose AD when inoculated with waste sewage sludge. The results revealed that the presence of AZM and TC led to significantly higher methane yields, with increases of 51.94% and 34.96%, respectively, during a 20-day AD period. In contrast, the presence of CLX resulted in a 23.95% lower methane yield compared to the control. Furthermore, detailed analyses indicated that AZM had a positive influence on cellulose AD at all stages, including methanogenesis, acidogenesis/acetogenesis, and hydrolysis. On the other hand, TC primarily promoted AD during the methanogenesis stage. These findings collectively offer valuable guidance for efficiently transforming the energy potential of lignocellulosic wastes.

Application of Electric Fields to Reduce Microorganism Contamination for Animal-Based Products

&lt;p&gt;Non-thermal preservation has become popular recently for the preservation of animal-based products. One of the non-thermal preservation methods is the electric field (EF) treatment of food, which can suppress enzyme and microorganism activity. The EF treatment itself consists of various types, including pulsed electric fields (PEF), high-voltage electric fields (HVEF), and alternating capacitive electric fields (ACEF and DCEF). This review discusses the EF treatment effects, especially PEF, on animal-based product preservation, including mechanisms, advantages and disadvantages, PEF application, and its preservation effect. PEF has the potential to be widely applied in food processing.&lt;/p&gt;

Daya Antibakteri Minyak Atsiri Cananga odorata terhadap Pertumbuhan Bakteri Streptococcus mutans ATCC 25175

Caries is a disease of dental hard tissue, which is caused by the activity of a cariogenic microorganism. Streptococcus mutans is a gram-positive, spherical, facultative anaerobic, non-motile bacterium. Streptococcus mutans acts as an agent that can cause dental caries. Herbal medicines are preferred by the community because the risk of side effects is lower than chemical drugs. The purpose of the study was to know the antibacterial property of Cananga odorata essential oil on the growth of Streptococcus mutans bacteria ATCC 25175. This study used a laboratory experimental research design with disc diffusion method to know the antibacterial property of Cananga odorata essential oil on the growth of Streptococcus mutans ATCC 25175. The results showed an inhibitory zone of 0.25 mm at a concentration of 6.25%; 1.43 mm at a concentration of 12.5%; 1.93mm at 25% concentration; 2.21 mm at 50% concentration; and 4.48 mm at a concentration of 100%. The conclusion of this study is Cananga odorata essential oil has a weak antibacterial property on the growth of Streptococcus mutans ATCC 25175.

ORGANIC FERTILIZER'S ROLE IN THE IMPROVEMENT OF SOIL MICROFLORA AND BIOMETRIC VALUES IN FRUIT CROPS

Intensive farming has adversely affected soil fertility and ecosystems due to excessive chemicalization in the Kazakhstan Republic. The soil lacks organic matter, leading to declining fertility. Biologization has emerged to address this issue as a solution to improve soil fertility and enhance the growth and development of crop plants. This study aimed to determine the impact of organic fertilizers on the composition of soil microflora and biometric values in cultivating stone and pome fruits. The use of microbiological methods analyzed soil microflora and physiological bacterial groups. The research’s novelty lies in developing a technology that utilizes organic fertilizers and biological products to improve the activities of soil microorganisms and plant roots’ nutrition. Organic fertilizers ‘Bio juice Energy Plus’ and ‘Agroflorin’ positively influenced beneficial bacteria and fungi and significantly contributed to soil enrichment. Organic fertilizers and biological products support soil biological processes and replenish the nutrients, promoting sustainable agricultural productivity and reducing chemical dependency. The current study emphasizes the potential of organic fertilizers and natural products in enhancing soil fertility and supporting plant growth in Kazakhstan. Biologization also offers an eco-friendly approach to agricultural practices, ensuring agronomic productivity and the long-term good health of soils.

Experimental study of the antibacterial efficacy of an antiseptic drug activated by ultrasound of different frequencies

Aim. To study the antibacterial efficacy of the antiseptic drug Miramistin, activated by ultrasound of different frequencies, against pathogenic microorganisms of periodontal pockets, in an experiment. Materials and methods. As an antiseptic drug, the drug Miramistin 0.01% was used, which was activated using ultrasound of different frequencies: high-frequency (880 kHz) in continuous mode for 4 minutes, low-frequency (26.5 kHz) in continuous mode for 2 minutes. To conduct the study, clinical strains of microorganisms obtained from periodontal pockets with moderate periodontitis were used: S. sanguis, S. pyogenes, P. intermedia, C. albicans. The study was carried out using automatic programmable cultivation, using the RTS-8 system. The studied samples of the antiseptic drug were previously diluted in a nutrient broth in a ratio of 2:200. Results. In the course of the study, it was found that with respect to pathogenic microorganisms obtained from periodontal pockets with moderate periodontitis, Miramistin in a dilution of 2:200, activated by low-frequency ultrasound, showed more pronounced antibacterial effect compared to Miramistin activated by high-frequency ultrasound. Conclusions. In the treatment of periodontitis, to suppress the vital activity of pathogenic microorganisms, preference should be given to the combined effects of low-frequency ultrasound and the antiseptic drug Miramistin.

Electric field as extracellular enzyme activator promotes conversion of lignocellulose to humic acid in composting process

To promote efficient conversion of lignocellulose to humus (HS) during composting, a novel bio-electrochemical technology was applied and explored the effect and mechanism of electrification on carbon conversion during different composting periods. The results showed that supplementary electric field played different roles during composting. In the early stage, organic matter mineralization was significantly accelerated under electric field application, that was embodied in a 29.8% increase of CO2 emission due to the enhanced metabolic activity of microorganisms. However, the electric field functioned as an extracellular enzyme activator during the later stage since the abundance of functional microorganisms related to lignocellulose degradation was increased by 1.5–2.8 fold that effectively promoted the conversion of lignocellulose to HS. The humic acid content of the compost products increased by 23.0–32.9% compared with control. This study elucidated how electric fields affect carbon conversion during composting, which provides a novel strategy for returning agricultural wastes to soil.

Microaerobic methane-driven denitrification in a biotrickle bed – Investigating the active microbial biofilm community composition using RNA-stable isotope probing

A microaerobic (2% O2 v/v) biotrickle bed reactor supplied continuously with 2% methane to drive nitrate removal (MAME-D) was investigated using 16S rDNA and rRNA amplicon sequencing in combination with RNA-stable isotope probing (RNA-SIP) to identify the active microorganisms. Methane removal rates varied from 500 to 1000 mmol m−3h−1 and nitrate removal rates from 25 to 58 mmol m−3h−1 over 55 days of operation. Biofilm samples from the column were incubated in serum bottles supplemented with 13CH4. 16S rDNA analysis indicated a simple community structure in which four taxa accounted for 45% of the total relative abundance (RA). Dominant genera included the methanotroph Methylosinus and known denitrifiers Nubsella and Pseudoxanthomonas; along with a probable denitrifier assigned to the order Obscuribacterales. The 16S rRNA results revealed the methanotrophs Methylocystis (15% RA) and Methylosinus (10% RA) and the denitrifiers Arenimonas (10% RA) and Pseudoxanthomonas (7% RA) were the most active genera. Obscuribacterales was the most active taxa in the community at 22% RA. Activity was confirmed by the Δ buoyant density changes with time for the taxa, indicating most of the community activity was associated with methane oxidation and subsequent consumption of methanotrophic metabolic intermediates by the denitrifiers. This is the first report of RNA stable isotope probing within a microaerobic methane driven denitrification system and the active community was markedly different from the full community identified via 16S-rDNA analysis.

Contribution of microorganisms from pit mud to volatile flavor compound synthesis in fermented grains for Nongxiangxing Baijiu brewing.

Nongxiangxing Baijiu (NB) is known for its distinct flavor profile which is attributed to key aroma compounds. The exposed fermentation technique, utilizing Daqu and solid-state fermentation in pit muds, plays a crucial role in flavor development. While previous studies have investigated the impact of microorganisms from pit mud and fermented grains on flavor compound production, a comprehensive understanding of microbial functions in the entire pit fermentation system is lacking. Herein, we aimed to explore the role of pit mud-derived microorganisms in shaping the microbial community and flavor compound synthesis in NB. There are 76 volatile flavor compounds were identified in fermented grains during Nongxiangxing Baijiu fermentation. Main flavor compounds in Nongxiangxing Baijiu clustered within the same network module. And 27.27% of microorganisms in the core modules of the fermented grain co-occurrence network originated from pit mud. The relationship between pit mud microorganisms and flavor compounds revealed a significant positive correlation (92%). Notably, Prevotella and Sarocladium were identified as the main contributors to this effect on flavor. Microorganisms originating from pit mud influenced the composition and activity of microorganisms in fermented grains and facilitated the production of flavor compounds in NB. This article is protected by copyright. All rights reserved.

Zeolite enhanced iron-modified biocarrier drives Fe(II)/Fe(III) cycle to achieve nitrogen removal from eutrophic water

The problem of nitrogen removal in eutrophic water needs to be solved. Two new autotrophic nitrogen removal technologies, ammonia oxidation coupled with Fe(III) reduction (Feammox) and Nitrate-dependent Fe(II) oxidation (NDFO), have been shown to have the potential to treat eutrophic water. However, the continuous addition of iron sources not only costs more, but also leads to sludge mineralization. In this study, nano-sized iron powder was loaded on the surface of K3 filler as a solid iron source for the extracellular metabolism of iron-trophic bacteria. At the same time, due to the high selective adsorption of zeolite for ammonia can improve the low nitrogen metabolism rate caused by low nitrogen concentrations in eutrophic water, three kinds of modified functional biological carriers were prepared by mixing zeolite powder and iron powder in different proportions (Z1, Zeolite:iron = 1; Z2, Zeolite:iron = 2; Z3, Zeolite:iron = 3). Z3 exhibited the best performance, with removal efficiencies of 54.8% for total nitrogen during 70 days of cultivation. The chemical structure and state of iron compounds changed under microorganism activity. The ex-situ test detected high NDFO and Feammox activities, with values of 1.02 ± 0.23 and 0.16 ± 0.04 mgN/gVSS/h. The enrichment of NDFO bacteria (Gallionellaceae, 0.73%-1.43%–0.74%) and Feammox bacteria (Alicycliphilus, 1.51%-0.88%–2.30%) indicated that collaboration between various functional microorganisms led to autotrophic nitrogen removal. Hence, zeolite/iron-modified biocarrier could drive the Fe(II)/Fe(III) cycle to remove nitrogen autotrophically from eutrophic water without carbon and Fe resource addition.

Regulation methods and enhanced mechanism on the efficient degradation of aromatics in biochemical treatment system of coal chemical wastewater

In order to address the problems of poor treatment effect of coal chemical wastewater (CCW) biochemical treatment system resulting in non-compliance with effluent standards and unstable operation, a combination regulation method of co-substrate metabolism and predominant flora enhancement was constructed, and the performance and mechanism of enhanced degradation of aromatics in CCW was also investigated in this study. The results showed that when the influent concentration of chemical oxygen demand (COD) and aromatics was less than 600 mg/L and 180 mg/L respectively, there was no significant effect of the combined regulation method on the enhanced treatment of aromatics, the removal rate of total organic carbon (TOC) in the system could all more than 73%; while when the influent concentration of COD increased to 800 mg/L and the aromatics concentration increased to more than 240 mg/L, the ordinary activated sludge system had collapsed. Compared with the regulation method of co-substrate metabolism alone, the combination regulation method increased the removal rate of TOC by 21%. The analysis of antioxidant enzyme activity showed that under the combination regulation method, the antioxidant enzyme activity of microorganisms was higher and their resistance to adverse environments was stronger. EPS and dehydrogenase analysis indicated that the combination regulation method was more conducive to microbial degradation of aromatics. Meanwhile, the analysis of microbial community structure showed that the aromatics degradation bacteria genera Rhodococcus, Luteococcus, etc. were enriched under the combination regulation method. The study provides a theoretical basis and technical guidance for solving the problems of unstable operation of CCW biochemical treatment systems and non-compliance with effluent standards.

Microbial induced calcium precipitation by Zobellella denitrificans sp. LX16 to simultaneously remove ammonia nitrogen, calcium, and chemical oxygen demand in reverse osmosis concentrates

In recent years, with the rapid development of industrial revolution and urbanization, the generation and treatment of a large number of salt-containing industrial wastewater has attracted wide attention. A novel salt-tolerant Zobellella denitrificans sp. LX16 with excellent nitrogen removal and biomineralization capabilities was isolated in this experiment. Kinetic experiments were conducted to determine the optimal condition. Under this condition, chemical oxygen demand (COD) can be entirely removed together with ammonia nitrogen, and the removal efficiency of calcium was 88.09%. Growth curves and nitrogen balance tests showed that strain LX16 not only had good HNAD and MICP capabilities, but also had high nitrite reductase and nitrate reductase activities during this process. Three-dimensional fluorescence results reflected that when external carbon sources were lacking or salinity was high, humic acid could effectively enhance the metabolic activity of heterotrophic nitrifying aerobic denitrifying microorganisms through extracellular electron transfer, and the substances produced in the metabolic process could promote biommineralization. Moreover, combined with SEM, SEM-EDS, XRD and FTIR analysis, it is concluded that the microbial surface can provide nucleation sites to form calcium salts, and with the increase of alkalinity to generate Ca5(PO4)3OH. The theoretical basis for the use of biological treatment in reverse osmosis wastewater have been proved by this experiment.

Labile carbon-induced soil organic matter turnover in a subtropical forest under different redox conditions

Labile organic carbon (LOC) input strongly affects soil organic matter (SOM) dynamics, including gains and losses. However, it is unclear how redox fluctuations regulate these processes of SOM decomposition and formation induced by LOC input. The objective of this study was to explore the impacts of LOC input on SOM turnover under different redox conditions. Soil samples were collected in a subtropical forest. A single pulse of 13C-labeled glucose (i.e., LOC) was applied to the soil. Soil samples were incubated for 40 days under three redox treatments, including aerobic, anoxic, and 10-day aerobic followed by 10-day anoxic conditions. Results showed that LOC input affected soil priming and 13C-SOM accumulation differently under distinct redox conditions by altering the activities of various microorganisms. 13C-PLFAs (phospholipid fatty acids) were analyzed to determine the role of microbial groups in SOM turnover. Increased activities of fungi and gram-positive bacteria (i.e., the K-strategists) by LOC input could ingest metabolites or residues of the r-strategists (e.g., gram-negative bacteria) to result in positive priming. Fungi could use gram-negative bacteria to stimulate priming intensity via microbial turnover in aerobic conditions first. Reduced activities of K-strategists as a result of the aerobic to anoxic transition decreased priming intensity. The difference in LOC retention in SOM under different redox conditions was mainly attributable to 13C-particulate organic carbon (13C-POC) accumulation. Under aerobic conditions, fungi and gram-positive bacteria used derivatives from gram-negative bacteria to reduce newly formed POC. However, anoxic conditions were not conducive to the uptake of gram-negative bacteria by fungi and gram-positive bacteria, favoring SOM retention. This work indicated that redox-regulated microbial activities can control SOM decomposition and formation induced by LOC input. It is extremely valuable for understanding the contribution of soil affected by redox fluctuations to the carbon cycle.

Sludge composting with self-produced carbon source by phosphate buffer coupled hyperthermophilic pretreatment realizing nitrogen retention

During sludge composting, ammonia emissions is the main pathway of nitrogen loss. In addition to regulating pH, increasing the carbon source is also important for controlling ammonia emissions. Previous studies have focused on additional carbon sources, while this study used phosphate-buffered saline (PBS) and hyperthermophilic pretreatment (HP) to release difficult-to-utilize carbon sources in extracellular polymeric substance (EPS) for composting. The PBS concentration was 0.22 mmol/g total matter (TM), PBS soaking days were 4.74, HP temperature was 149.46 °C, and the soluble chemical oxygen demand (SCOD) was 45.08 g/kg. Compared with the control check, the peak ammonia emission concentration in the pretreated group was reduced by 8.70 % and the total nitrogen loss was reduced by 18.10 %. Changes in EPS, ammonia assimilation activity, and microbial community composition demonstrated that PBS and HP released the carbon source from the sludge, promoted ammonia assimilation, and enriched bacteria related to ammonia assimilation such as Bacillus (16.52 %). HP treatment made Acinetobacter (12.5 %) the dominant genus in the calefactive phase, and the enrichment of Actinobacteriota (27.27 %) promoted the composting maturity. However, total pretreatment reduced the porosity and permeability of the sludge and affected the activity of microorganisms. Considering the cost of energy consumption, partial pretreatment has more practical application prospects.

Microbial bioremediation: Effective Strategy for Removal of Pollutants from Contaminated Industrial Water of Textile Mills Plants. An Overview

Bioremediation is a process used to treat contaminated water by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants. Microbial bioremediation uses microorganisms to break down contaminants by using them as a food source. These toxic compounds are metabolized by enzymes of microorganisms. The industrial water contaminated by heavy metals and other pollutants are common throughout the world. Many strategies are developed to encourage the degradation of pollutants from such affected sites. Bioremediation as one feasible way to be used. It is a technology that employs living microorganisms such as bacteria and fungi to remove harmful contaminants from the polluted environment. The basis of bioremediation is that microorganisms remove substances from the environment to carry out their growth and metabolism. The microorganisms used in this strategy can be both indigenous and non-indigenous. These microorganisms take part in the degradation, immobilization, and detoxification of various harmful chemical wastes and contaminants. Microorganisms which perform the function of bioremediation are known as bio-remediators or bio-reformers. The treatment of contaminated water by the conventional method is found to be unfeasible due to its high cost and generates secondary pollutants. Therefore, bioremediation is not effective only for the degradation of pollutants but it can also be used to clean unwanted substances in industrial water and raw materials form industrial waste through the biological activities of microorganisms. Microbial growth depends on several environmental factors such as pH, temperature, and nutrients. The practice bio-stimulation that involves the addition of nutrients to the contamination site enhances the growth of microbes that assist in bioremediation. One of the main nutrients is molasses, in Iraq we used a natural material (dates extracts) in bioremediation of industrial water of textile mills plants.

Exploration and application of microbial method to enhance the effect of hydraulic fracturing on coal seam permeability enhancement and gas extraction

The efficient extraction of gas from low-permeability coal seams is an urgent problem in coal mine safety production. The traditional gas extraction technology generally suffers from problems that limited penetration enhancement or extraction effect, low construction efficiency, large workload, etc. Thus, it is especially urgent and important to explore the new technology applicable to efficient underground gas extraction. In this paper, based on the principle of hydraulic fracturing to increase permeability, we innovatively propose a technique to enhance the effect of hydraulic fracturing to increase permeability and further improve the efficiency of gas extraction using the gas desorption activity of native microorganisms in coal seams. Herein, the composition of the primary microbial community of a coal seam in Xinji No.2 mine was analyzed by bacterial and archaeal 16SrDNA amplicon sequencing, the community structure of the main functional microorganisms was clarified, the optimal combination of functional microorganisms for organic matter degradation in coal seam under anaerobic culture conditions was obtained. Besides the Biolog microplate technology was used to screen the nutrients of the excitation carbon source to stimulate the rapid decomposition of coal organic matter by microorganisms and to define the optimal ratio of the excitation carbon source to microorganisms. Finally, the effect of this technology on the application of coal seam fracturing and gas extraction was tested through field industrial tests, revealing that the extraction effect of this technology was more significant than that of the common coal seam perforation extraction technology. The results of this paper provide a new technical idea for gas extraction from low permeability coal seams, which is an important reference value for subsequent similar studies.

Community composition and physiological plasticity control microbial carbon storage across natural and experimental soil fertility gradients

Many microorganisms synthesise carbon (C)-rich compounds under resource deprivation. Such compounds likely serve as intracellular C-storage pools that sustain the activities of microorganisms growing on stoichiometrically imbalanced substrates, making them potentially vital to the function of ecosystems on infertile soils. We examined the dynamics and drivers of three putative C-storage compounds (neutral lipid fatty acids [NLFAs], polyhydroxybutyrate [PHB], and trehalose) across a natural gradient of soil fertility in eastern Australia. Together, NLFAs, PHB, and trehalose corresponded to 8.5–40% of microbial C and 0.06–0.6% of soil organic C. When scaled to “structural” microbial biomass (indexed by polar lipid fatty acids; PLFAs), NLFA and PHB allocation was 2–3-times greater in infertile soils derived from ironstone and sandstone than in comparatively fertile basalt- and shale-derived soils. PHB allocation was positively correlated with belowground biological phosphorus (P)-demand, while NLFA allocation was positively correlated with fungal PLFA : bacterial PLFA ratios. A complementary incubation revealed positive responses of respiration, storage, and fungal PLFAs to glucose, while bacterial PLFAs responded positively to PO43-. By comparing these results to a model of microbial C-allocation, we reason that NLFA primarily served the “reserve” storage mode for C-limited taxa (i.e., fungi), while the variable portion of PHB likely served as “surplus” C-storage for P-limited bacteria. Thus, our findings reveal a convergence of community-level processes (i.e., changes in taxonomic composition that underpin reserve-mode storage dynamics) and intracellular mechanisms (e.g., physiological plasticity of surplus-mode storage) that drives strong, predictable community-level microbial C-storage dynamics across gradients of soil fertility and substrate stoichiometry.

Improving our Understanding of Environmental Stress Impacts and Responses of the Microbiome

Over the course of this century, it will be important to identify cost effective/low maintenance solutions for treating contaminants in receiving watersheds. Adopting these strategies will involve a better understanding of what defines a “natural” environment compared to these contaminated sites. Traditional geochemical testing and standard microbial community analyses (e.g., DNA profiling) or using isolates can be limited with respect to their ability to infer real-time, active processes of bacterial communities. In recent years the application of genomics to identify the microbial microbiome in anthropogenic stressed conditions has advanced considerably. In many cases, the activity of microorganisms will directly impact the chemical conditions in both surface and subsurface water column and contaminated sediment environments controlling the fate of nutrients and contaminants alike. Questions arise such as: What are the baselines or reference systems that can be used? What indices can be used to study the long-term and short-term controls on the mobility, cycling, and bioavailability of toxic metals and organic contaminants? What are the baselines or reference systems that can be used? What indices can be used to study the long-term and short-term controls on the mobility, cycling, and bioavailability of toxic metals and organic contaminants? In many cases the balance of chemical oxidizing and reducing components in water will control the development of chemical and nutrient gradients observed in either natural and/or applied systems (e.g., constructed wetlands or bioreactors). In these cases, biogeochemical systems will determine the direction and onset of specific metabolic pathways as defined by their favorable thermodynamic outcome, an issue for most bioremediators (i.e., microorganisms). Also, the degree of chemical alteration (toxicity or degradation products) can be directly linked to the proportion of their biological activity. In this presentation, contrasting case studies highlighting natural (baseline) and anthropogenically impacted landscapes will be discussed. The focus will be on identifying and linking physicochemical processes to microbial community function using emerging omics for geochemical applications and ascertaining novel contaminant bioindicators.

Performance of a recirculated biogas-sparging anaerobic membrane bioreactor system for treating synthetic swine wastewater containing sulfadiazine antibiotic

Anaerobic Membrane Bioreactor (AnMBR) is an efficient system for treating synthetic swine wastewater (SW). However, the presence of antibiotics in SW discourages the activity of microorganisms, resulting in less pollutants removal and biogas production. In this paper, a recirculated biogas-sparging anaerobic membrane bioreactor system was used to treat swine wastewater containing sulfadiazine (SDZ). The effects of different concentrations of SDZ on the AnMBR system’s performance were explored, in terms of pollutant removal, biogas production, membrane fouling and microbial community. Results indicated that the larger concentration of SDZ triggered a strong suppression in the system’s performance. When treating 1.0 mg/L SDZ, the biogas-sparging AnMBR system achieved about 77 % COD removal and 0.23 L/g CODremoved biogas production, which without SDZ fell to 21 % COD being removed and dropped biogas production by 30 %. As well, the presence of SDZ (1.0 mg L) increased by about half the amount of soluble microbial product (SMP) and extracellular polymeric substances (EPS) with lower protein/polysaccharide ratio and reduced sludge particle size by 49 %. Meanwhile, microbial community analysis revealed that the abundance of Firmicutes increased while Chloroflexi diminished. These jointly contributed to a shorter membrane fouling cycle declining from the initial 23 d to 7 d. Furthermore, the shift from acetoclastic methanogens to hydrogenotrophic methanogens resulted in less methane production due to the presence of SDZ, while the hydrogenotrophic methanogen Methanobacterium promoted the degradation of SDZ. The work showed AnMBR can effectively treat swine wastewater containing antibiotics and provides basis for practical application.