Bacteria In Leachate Research Articles

Bacterial Teaching Material Supplement Based on the Study of Identification of Resistant Bacteria in Leachate at TPA Talumelito as a Virtual Laboratory-Based Digital Learning Resource

Differentiated learning is the core of the independent curriculum now.The aim of this research is to develop an instrument for measuring the cognitive learning outcomes of high school students based on differentiated learning on elasticity material and to obtainits characteristics. Differentiation, in this case, is differentiation of student learning styles. The instrument grid is arranged based on indicators of cognitive learning outcomes, which are then used to compile question items. The test instrument consists of two test sets, each of which has 9 items including two anchor itemsso that the total number of items is 16 items and has been validated by 6 experts. The validated instrument was tested on 252 respondents spread across high schools in the low, medium and high categories. Dichotomous data were analyzed using the Partial Credit Model (PCM). The trial results showed that all 16 items and the differentiated learning-based student cognitive learning outcomes test instrument were proven to be valid, fit the PCM model, and reliable, which means all items were in the good category. Thus, the test instrument developed meets the requirements for measuring the cognitive learning outcomes of high school students on elasticity material based on differentiated learning.

Examination of bacteria content of leachate concentration in open dumpsites, at Gwagwalada, Federal Capital Territory, Abuja, Nigeria

The bacteria content of leachate concentration in open dumpsite is a threat to man and its environment if not properly managed. One of the negative impacts of bacteria in leachate is that it may pollute water system which may lead to diseases if not prevented. In this study, the leachate concentrates were collected from five different location of open dumpsite in Gwagwalada town and examined bacteriologically. Using pour plate method, bacteria were counted and isolated. Biochemical tests and Molecular identification of bacteria isolate based on DNA extraction, DNA quantification and 16S rRNA Amplification were carried out. The total coliform bacterial counts ranged from 4.1× 105cfu/ml - 4.8×105cfu/ml. Isolated bacteria with percentage occurrence were Staphylococcus spp. (37.14%), Klebsiella aerogenes (25.71%), Proteus spp. (20%), Priestia megaterium (11.43%), Pseudomonas stutzeri (2.86%) and Enterobacter hormaechei (2.86%). Generally, both gram positive organisms showed 100% susceptibility to Pefloxacin and Cotrimoxazole and exhibited 100% resistance to Ampliclox while all gram negative bacteria showed 100% susceptibility to Ciprofloxacin. The biochemical test and molecular identification of bacteria isolates showed the presence of pathogenic bacteria which is hazardous to human health within the environment due to the possibility of contamination of drinkable water. As a result, the government and environmental agency should work together in preventing the situation of open dumpsite around residential areas through educational and awareness program.

Effectiveness of Biochar and Zeolite Soil Amendments in Reducing Pollution of Municipal Wastewater from Nitrogen and Coliforms

A greenhouse experiment with soil cores and wastewater application was carried out to investigate the effects of biochar and zeolite on the mobility of nitrogen and coliform bacteria during the leaching of columns repacked by a silty loam soil. Triticum aestivum plants were grown in cores with and without biochar and zeolite irrigated with municipal wastewater for 4 months in the greenhouse. Cores were then flushed with 800 mLof distillate water and, finally, the leachate was collected. Application of biochar or zeolite significantly (p ≤ 0.05) reduced nitrate and ammonium loss in soil after leaching process, compared to their non-treated counterparts. In addition, interactions of biochar and zeolite significantly decreased nitrate and ammonium content in leachate. Biochar had higher removal effects of coliform bacteria in leachate than zeolite. Lower nitrate and ammonium content in leachate was related to the increased retention of soil amendments. Application of 5% w/w of biochar also reduced the volume of leachate by 11% compare to control, but using 5% w/w and 10% w/w of zeolite increased the volume of leachate compared with non-treated columns by 21% and 48%, respectively. Taken together, these data highlight the need to consider the potential benefits of biochar and zeolite as soil amendment to reduce nitrogen mobility and remove coliform bacteria in the leaching process of municipal wastewater in agricultural systems.

Intensification of Nickel Bioleaching with Neutrophilic Bacteria Guyparkeria halophila as an Approach to Limitation of Sulfuric Acid Pollution.

Hydrometallurgical production of valuable and non-ferrous metals is traditionally accompanied with acid waste effluents/acid mine drainage leading to acidification of the mining areas. The traditional cause of this pollution is the well-known technology based on the recovery of metals with acid solutions and the application of strong acidophilic leaching bacteria for the oxidation of sulfide ores. In our experiments, we used neutrophilic autotrophic bacteria (NAB) stimulated with formic acid or coupled with acidophilic bacteria. The first approach was based on using formic acid as an energetic substrate by autotrophic bacteria. In the second case, the NAB provided initial biogenic acidification for the following growth of the inoculated acidophilic bacteria. Our experiments resulted in increased nickel recovery from the low-grade sulfide ores, which was provided by the NAB in a medium supplemented with formic acid. Bioleaching resulted in 1116 mg Ni/L (69.75%) in the medium with formate and only 35.4 mg Ni/L without formate in 43 days. As a whole, our bench scale experiments showed that the stimulated NAB can be effective at pH 7–5. Partially replacing sulfuric acid with formic acid could also give benefits via the following natural degradation of acid wastes. As a whole, this approach is more environmentally friendly than conventional bioleaching techniques.

Contributions of meat waste decomposition to the abundance and diversity of pathogens and antibiotic-resistance genes in the atmosphere

Airborne transmission of antibiotic-resistance genes (ARGs) in landfill and acquisition of antibiotic resistance by pathogenic bacteria are posing potential threat to human and environmental health. However, little is known about contribution of waste decomposition to airborne ARGs and pathogens during landfilling of household waste. Herein, the dynamic changes of microbial communities and ARGs were comparatively investigated in leachate and bioaerosol during the decomposition of chicken, fish, and pork wastes. Results found that chicken and pork decomposition could result in emitting high abundance of bioaerosol and pathogen, while fish fermentation will lead to high airborne microbial activity. The main pathogens were Bacilli, Burkholderia-Paraburkholderia and Mycobacterium in bioaerosols, but were Wohlfahrtiimonas, Peptoniphilus and Fusobacterium in leachate, suggesting that the ability of aerosolization of bacteria in leachate was independent of their abundance and diversity. Whereas, diversity and relative abundance of ARGs in leachate were significantly higher than bioaerosol. Moreover, the relative abundance of ARGs in leachate and bioaerosols was not completely relevant. The changes of pathogenic community contributed significantly to the prevalence of ARGs in bioaerosol and leachate. The results will define the contribution of household waste decomposition to airborne pathogen and ARG distribution and provide foundation for airborne bacterial exposure risk and control in landfill.

Adsorption of Escherichia coli from landfill leachate using Dredged marine soils as Geosorbent: The influence of temperature

The heat generated by biodegradation in landfill site led to an increase in landfill temperature. This phenomenon considered to be a consequence of the heat generated by the biodegradation process. The increasing temperature is one of the stress factors for the bacteria in the landfill site. This factor will interfere with the cell’s metabolism and suppress the bacteria to grow. The focus of this study is to look into the influence of temperature on the adsorption ofEscherichia coli(E. coli) from landfill leachate using a geosorbent. The geosorbent was made from Dredged Marine Soils (DMS). The application of geosorbent as landfill liner could potentially entrap and reduce the pathogenic bacteria in leachate. Least number ofE. coliwas found in the landfill leachate at high-temperature degree. Concurrently a high number ofE. coliwas counted in the geosorbent. Findings from this study supported the idea thatE. coligrowth in landfill leachate was suppressed by the increment of the temperature. As a result,E. colideveloped strategies to respond against this environmental stress. TheE. colishifted from landfill leachate to the geosorbent seeking for protection. In general, the geosorbent using DMS material demonstrated the ability to adsorb bacteria at varied temperature degree.

Isolation distance between municipal solid waste landfills and drinking water wells for bacteria attenuation and safe drinking

Groundwater pollution and human health risks caused by leachate leakage have become a worldwide environmental problem, and the harm and influence of bacteria in leachate have received increased attention. Setting the isolation distance between landfill sites and groundwater isolation targets is particularly important. Firstly, the intensity model of pollutant leakage source and solute transport model were established for the isolation of pathogenic Escherichia coli. Then, the migration, removal and reduction of bacteria in the aerated zone and ground were simulated. Finally, the isolation distance was calculated based on the acceptable water quality limits, and the influence of hydrogeological arameters was analyzed based on the parameter uncertainty. The results of this study suggest that the isolation distances vary widely ranging from 106 m–5.46 km in sand aquifers, 292 m–13.5 km in gravel aquifers and 2.4–58.7 km in coarse gravel aquifers. The gradient change of groundwater from 0.001 to 0.05 resulted in the isolation distance at the highest gradient position being 2–30 times greater than that at the lowest gradient position. There was a difference in the influence of the thickness of the vadose zone. For example, under the same conditions, with the increase of the thickness of the aeration zone, the isolation distance will be reduced by 1.5–5 times, or under the same thickness of the aeration zone, the isolation distance will be significantly shortened. Accordingly, this needs to be determined based on specific safety isolation requirements. In conclusion, this research has important guiding significance for the environmental safety assessment technology of municipal solid waste landfill.

Blank roasting and bioleaching of stone coal for vanadium recycling

Abstract The recovery and utilization of vanadium from stone coal is of great significance because it is an important metal. In the present study, a cleaner metal extraction method to recover vanadium from low-grade stone coal using a novel strain of Bacillus mucilaginosus (BM) and an enhanced bioleaching procedure was explored. The efficient leaching bacteria of BM-5070 were obtained by the atmospheric and room temperature plasma (ARTP)-hydroxylamine hydrochloride compound mutagenesis technique. The results show that BM-5070 had the highest V leaching rate. After a 20-day bioleaching period, the V leaching rate of BM-5070 was 5.5 percentage points higher than that of the original bacteria. Moreover, the pretreatment of stone coal by blank roasting without any additives can further promote the vanadium dissolution, and the V leaching rate reached 85% after bioleaching for 20 days, which was 57 percentage points higher than that of without roasting. This is due to the decrease in the content of V (III) and the increase in the V (V) and V (IV) content after blank roasting, which is beneficial to the leaching of vanadium. The bioleaching behavior was elucidated through the bacteria-mineral contact leaching and non-contact leaching test. The results show that the V leaching rate (81.0%) in the contact mode was much higher than that in the non-contact leaching mode (64.4%), indicating that the bioleaching of vanadium occurs with direct action and indirect action. The results of our study could significantly contribute to a green method for recovering vanadium from stone coal.

Anaerobic/aerobic conditions determine antibiotic resistance genes removal patterns from leachate by affecting bacteria taxa-genes co-occurrence modules

Landfill treatment of municipal solid waste treatment produces a large amount of leachate, which has been an important hotspot of ARGs. This study aimed to investigate the ARGs removal potential, kinetics and mechanism from leachate in aerobic and anaerobic conditions. Simulated landfill reactors showed the efficacy in reducing ARGs, and the removal efficiencies depended on ARGs types and aerobic/anaerobic conditions. The ARGs tetQ and blaCTX-M were more likely to attenuate with the log-removal efficiencies of 1.50–3 order of magnitude. The ARGs removal kinetic was well fitted by modified Collins-Selleck model, and aerobic condition showed better removal capacities and kinetics than anaerobic condition. Among the ARGs with great removal performance, sul2, aadA1and blaCTX-M were eliminated from leachate and refuse simultaneously, but tetM, ermB, and mefA were removed from leachate but enriched in refuse. Aerobic/anaerobic states might drive the bacterial community shift of leachate and refuse, and topology property comparison of co-occurrence networks suggested that refuse had a closer non-random host relationship between ARGs and microbial taxa than leachate. Further module analyses revealed that ARGs removal efficiencies depended on the taxonomy of host bacteria in leachate, while the refuse taxa-ARGs correlation determined ARGs removal patterns. By selecting distinct bacteria cluster in different conditions, aerobic treatment benefited ARGs reduction in leachate and refuse, while anaerobic treatment enhanced the enrichment of ARGs in refuse. These findings can potentially foster the understanding of ARGs removal mechanism in biological treatment processes.

Reuse of dredged marine soils as landfill liner: Effect of pH on Escherichia coli growth

A potential reuse area yet to be explored is the utilization of dredged marine soils (DMS) as geosorbent to retain pathogenic bacteria in landfill leachate. The use of DMS as geosorbent in landfill site could be considered as a new way of environmental friendly solid waste management. By laying DMS at the base of landfill like conventional clay liners, the geowaste could be simultaneously disposed of and act as passive geosorbent for microbes in leachate. DMS are known to serve as a hospitable environment for bacteria growth. Environmental factors such as soil’s pH, salinity and particle size could affect the bacteria growth rate. This study investigated the effect range of pH value on the growth of indicator bacteria, Escherichia coli (E. coli) isolated from landfill leachate. The results showed that the number of E. coli grew higher in alkaline compared to acidic condition. Findings from this study will serve as a base for future studies for removing bacteria in leachate using DMS as geosorbent in a landfill site.

A new route of bioaugmentation by allochthonous and autochthonous through biofilm bacteria for soluble chemical oxygen demand removal of old leachate

ABSTRACTLandfill leachate contains environmental pollutants that are generally resistant to biodegradation. In this study, indigenous and exogenous bacteria in leachate were acclimated in both biofilm and suspension forms to increase the removal of soluble chemical oxygen demand (SCOD). The bacteria from the leachate and sewage were acclimated to gradually increasing leachate concentration prepared using a reverse osmosis membrane over 28 days. The SCOD removal was measured aerobically or nominally anaerobically. Biofilms were prepared using different carrier media (glass, rubber, and plastic). The maximum SCOD removal in suspensions was 32% (anaerobic) and in biofilms was 39% (aerobic). In the suspension form, SCOD removal using acclimated bacteria from leachate and sewage anaerobically increased in comparison with the control (P < .05). In the biofilm form, the aerobic condition and the use of acclimated bacteria from leachate and sewage increased the removal efficiency of SCOD in comparison with other biofilm groups (P < .05). Three species of bacteria, including Bacillus cereus, Bacillus subtilis, and Pseudomonas aeruginosa were identified in the biofilm from leachate and sewage. Bioaugmentation technology using biofilms and acclimations can be an effective, inexpensive, and simple way to decrease SCOD in old landfill leachate.

Enhanced anaerobic digestion performance via combined solids- and leachate-based hydrolysis reactor inoculation

Suboptimal conditions in anaerobic digesters (e.g., presence of common inhibitors ammonia and salinity) limit waste hydrolysis and lead to unstable performance and process failures. Application of inhibitor-tolerant inocula improves hydrolysis, but approaches are needed to establish and maintain these desired waste-hydrolyzing bacteria in high-solids reactors. Herein, performance was compared for leach bed reactors (LBRs) seeded with unacclimated or acclimated inoculum (0–60% by mass) at start-up and over long-term operation. High quantities of inoculum (∼60%) increase waste hydrolysis and are beneficial at start-up or when inhibitors are increasing. After start-up (∼112days) with high inoculum quantities, leachate recirculation leads to accumulation of inhibitor-tolerant hydrolyzing bacteria in leachate. During long-term operation, low inoculum quantities (∼10%) effectively increase waste hydrolysis relative to without solids-derived inoculum. Molecular analyses indicated that combining digested solids with leachate-based inoculum doubles quantities of Bacteria contacting waste over a batch and supplies additional desirable phylotypes Bacteriodes and Clostridia.

Sulfur Oxygenase Reductase (Sor) in the Moderately Thermoacidophilic Leaching Bacteria: Studies in Sulfobacillus thermosulfidooxidans and Acidithiobacillus caldus.

The sulfur oxygenase reductase (Sor) catalyzes the oxygen dependent disproportionation of elemental sulfur, producing sulfite, thiosulfate and sulfide. Being considered an “archaeal like” enzyme, it is also encoded in the genomes of some acidophilic leaching bacteria such as Acidithiobacillus caldus, Acidithiobacillus thiooxidans, Acidithiobacillus ferrivorans and Sulfobacillus thermosulfidooxidans, among others. We measured Sor activity in crude extracts from Sb. thermosulfidooxidans DSM 9293T. The optimum temperature for its oxygenase activity was achieved at 75 °C, confirming the “thermophilic” nature of this enzyme. Additionally, a search for genes probably involved in sulfur metabolism in the genome sequence of Sb. thermosulfidooxidans DSM 9293T was done. Interestingly, no sox genes were found. Two sor genes, a complete heterodisulfidereductase (hdr) gene cluster, three tetrathionate hydrolase (tth) genes, three sulfide quinonereductase (sqr), as well as the doxD component of a thiosulfate quinonereductase (tqo) were found. Seven At. caldus strains were tested for Sor activity, which was not detected in any of them. We provide evidence that an earlier reported Sor activity from At. caldus S1 and S2 strains most likely was due to the presence of a Sulfobacillus contaminant.

Variability in the Concentration of Indicator Bacteria in Landfill Leachate – A Comparative Study

Leachate collected from the collection ponds of four landfill sites was investigated and compared for total coliforms and E. coli concentration as representatives of fecal pollution. Concentration of total coliforms and E. coli was comparable for leachate obtained from Kulim Landfill Site (KLS) and Ampang Landfill Site (ALS) with little variations. However, the level of indicator bacteria was significantly lower for Kuala Sepetang Landfill Site (KSLS), whereas Pulau Burung Landfill Site (PBLS) had the lowest concentration for both total coliforms and E. coli. Considering the landfills are currently operational, with the exception of ALS, the presence of indicator bacteria implies their inactivation prior to discharge. High concentration of indicator bacteria in ALS is attributed to the run-off entering the leachate pond. Greater concentration of ammonia and salinity level were partly responsible for lower concentration of indicator bacteria in leachate from KSLS and PBLS, indicating that salinty and ammonia could significantly affect the survival of indicator bacteria.

Accumulation of Lactic Acid during Biodigestion of Municipal Solid Waste Leachate and Identification of Indigenous Lactic Acid Bacteria in Leachate

AbstractLactic acid accumulation is a common phenomenon in animal bodies during anaerobic respiration, but it is rarely found in natural systems like cattle manure digestion plants or anaerobic municipal sewage sludge bioreactors. The objective of this study was to demonstrate lactic acid production and accumulation during anaerobic digestion of municipal solid waste (MSW) leachate. Three reactors were set up containing cow dung, cow dung plus leachate, and only leachate to carry out anaerobic digestions. The amount of lactic acid accumulated in the reactor containing cow dung only was much less in comparison to the reactor containing cow dung plus leachate. This may be because of the suppression of sulphate reducing bacteria (SRB) and other groups of bacteria which utilize lactic acid, by some component in MSW leachate. The accumulated lactic acid might have come from various bacterial sources. For the identification of responsible organisms, the authors performed polymerase chain reaction (PCR), cloning...

Biofilm Formation, Communication and Interactions of Mesophilic Leaching Bacteria during Pyrite Oxidation

A functional luxIR-type Quorum Sensing (QS) system is present in Acidithiobacillus ferrooxidans. However, cell-cell communication among various acidophilic chemolithoautotrophs growing on pyrite has not been studied in detail. These aspects are the scope of this study with emphasis on the effects exerted by the N-acyl-homoserine lactone (AHL) type signaling molecules which are produced by Acidithiobacillus ferrooxidans. Their effects on attachment and leaching efficiency by other leaching bacteria, such as Acidithiobacillus ferrivorans, Acidiferrobacter spp. SPIII/3 and Leptospirillum ferrooxidans in pure and mixed cultures growing on pyrite is shown.

가축 매몰지 침출수에 대한 수질 특성 및 호기성 미생물 분포에 관한 연구

가축 매몰지내 침출수의 누출은 인간과 다른 가축들에게 쉽게 질병을 확산시킬 수 있는 중요한 문제이다. 본 연구에서는 매몰된지 5개월 이내의 초기 16개 가축매몰지에 대한 침출수의 물리화학적 특성과 분자미생물학적 방법을 이용하여 침출수내 존재하는 호기성 미생물을 분석하였다. 총대장균군, 총유기탄소, 암모니아이온 및 질산성질소가 관련된 참고문헌자료에 비하여 높게 나타났다. 또한 암모니아 이온과 질산성질소는 국내 먹는물 기준치를 초과하여 나타났다. 16S rNA 서열 분석법을 사용하여 호기성 조건에서 침출수의 미생물 분포를 분석한 결과, 높은 빈도의 Bacillus pumilus, Lysinibacillus sphaericus 및 Bacillus sphaericus이 관찰되었지만, Bucillus cereus와 Salmonella와 같은 식중독 미생물은 발견되지 않았다. 본 연구는 가축매몰지로부터 형성되는 침출수에 대한 지질 매체 내에서의 거동특성, 처리 및 위해성 평가에 대한 기초자료로 활용 가능할 것이다. Leakage of leachate from animal carcass disposal is a significant issue because disease can easily spread to humans and other livestock. In this study, we analyzed the physicochemical properties of leachate and tested for the presence of aerobic bacteria in leachate using molecular biology methods, for 16 animal carcass disposals in the first stage (after burial for 5 months). Leachate physicochemical analysis revealed higher total coliforms, TOC, <TEX>$NH^{4+}$</TEX>, and <TEX>$NO^{3-}$</TEX> concentrations compared with previously published data. In most leachate samples, the concentrations of <TEX>$NH^{4+}$</TEX> and <TEX>$NO^{3-}$</TEX> exceeded the Korean guideline values for drinking water. In 16S rRNA sequence analysis of the distribution of leachate under aerobic conditions, Bacillus pumilus, Lysinibacillus sphaericus, and B. sphaericus were observed with high frequency, whereas no food-poisoning-related bacteria such as B. cereus or Salmonella were detected. The present findings improve our knowledge of the transport of leachate from animal carcass disposal sites through geologic media, and are useful in risk analysis and for subsequent studies.

Interfacial insights of pyrite colonized by Acidithiobacillus thiooxidans cells under acidic conditions

Studies of interfacial processes involving leaching bacteria and sulfide minerals (MS) are necessary to understand and improve the bioleaching processes of mining industries. Interfacial studies of the role of extracellular polymeric substances (EPSs) during cell attachment to MS have been restricted mainly to iron-oxidizing bacteria, neglecting interfacial mechanisms associated with the biooxidation of reduced sulfur compounds (e.g., elemental sulfur, S 0); nevertheless the reduced sulfur compounds may affect MS weathering or dissolution. The importance of sulfur-oxidizing microorganisms is evidenced by the fact that S 0 was generally added to promote the growth of Acidithiobacillus thiooxidans in some bioleaching processes. Preliminary research coupled either epifluorescence and atomic force microscopy (AFM) or Raman spectroscopy and AFM to analyze biofilms of A. ferrooxidans on pyrite or the surface features of pyrite in biotic and abiotic experiments. Here, we applied the combination of AFM, Raman and principles of epifluorescence for the study of biofilms of the A. thiooxidans on previously oxidized pyrite. Our results showed that A. thiooxidans forms a monolayered biofilm, wherein the contact resulted in a strong adhesion force (467 pN) between the cells and the altered surface, perhaps due to an irreversible binding mechanism. The observations strongly suggested an intimate contact stage during the dynamic interfacial mechanisms of S 0 biooxidation on the pyrite surface. During this process, an overproduction of EPS was recorded (ca. 100%), indicating that EPS plays a key role during microorganism/surface interactions.

Bioleaching of spent hydro-processing catalyst using acidophilic bacteria and its kinetics aspect

Bioleaching of metals from hazardous spent hydro-processing catalysts was attempted in the second stage after growing the bacteria with sulfur in the first stage. The first stage involved transformation of elemental sulfur particles to sulfuric acid through an oxidation process by acidophilic bacteria. In the second stage, the acidic medium was utilized for the leaching process. Nickel, vanadium and molybdenum contained within spent catalyst were leached from the solid materials to liquid medium by the action of sulfuric acid that was produced by acidophilic leaching bacteria. Experiments were conducted varying the reaction time, amount of spent catalysts, amount of elemental sulfur and temperature. At 50 g/L spent catalyst concentration and 20 g/L elemental sulfur, 88.3% Ni, 46.3% Mo, and 94.8% V were recovered after 7 days. Chemical leaching with commercial sulfuric acid of the similar amount that produced by bacteria was compared. Thermodynamic parameters were calculated and the nature of reaction was found to be exothermic. Leaching kinetics of the metals was represented by different reaction kinetic equations, however, only diffusion controlled model showed the best correlation here. During the whole process Mo showed low dissolution because of substantiate precipitation with leach residues as MoO 3. Bioleach residues were characterized by EDX and XRD.

Combined Atomic Force and Fluorescence Microscopy of Biofilms formed by Leaching Bacteria on Opaque Substrata

Leaching bacteria attach to their substrates, i.e. mineral sulfides, and form monolayered biofilms. In this study the biofilm formation of Acidithiobacillus ferrooxidans A2 on pyrite was examined using atomic force and epifluorescence microscopy (AFM and EFM, respectively). A novel system by JPK instruments, the BioMaterial WorkstationTM, allows the investigation of the same location on an opaque sample with AFM and EFM. Until recently this was only possible for translucent samples. Sessile bacteria on pyrite coupons were stained with 4’,6-diamidino-2- phenylindol (DAPI) and visualized by EFM as well as AFM. The best imaging conditions for AFM were assessed. Scans of bacteria attached to pyrite were performed in contact mode in air as well as in tapping mode in fluid. Imaging in fluid was more challenging than imaging in air as bacteria tend to detach from their substratum. To avoid the dislocation of microorganisms by the AFM probe the sample was dried in air for 1 h prior to scanning in fluid. Scanning in air was performed with the whole range of cantilever spring constants tested (k = 0.03 N/m to k = 0.65 N/m) while, for scanning in fluid, best results were achieved using stiffer cantilevers (k = 0.65 N/m).