Small-Scale Expression of Proteins in E. coli

This study determined the distribution patterns of Escherichia coli O157:H7 in ground beef when a contaminated beef trim was introduced into a batch of uncontaminated beef trims prior to grinding in a small-scale laboratory grinder. A beef trim (15.3 ± 2 g) was inoculated with a rifampicin-resistant strain of E. coli O157:H7 (E. coli O157:H7rif) and introduced into a stream of noncontaminated beef (322 ± 33 g) prior to grinding. Seven inoculum levels (6, 5, and 4 total log CFU [high]; and 3, 2, 1, and 0 total log CFU [low]) were studied in triplicate. E. coli O157:H7rif was not detected in 3.1 to 43% of the ground beef inoculated with the high levels or in 3.4 to 96.9% of the ground beef inoculated with the low levels. For all inoculum levels studied, the five ground beef fractions (each 7.8 ± 0.6 g) with the highest pathogen levels accounted for 59 to 100% of the total pathogens detected. For all inoculum levels, there was a linear relationship between the quantity of ground beef containing E. coli O157:H7rif and the inoculum level. The quantity of E. coli O157:H7rif in the beef remaining in the grinder was proportional to the inoculum level and was related to the location in the grinder. Different components of the grinder accumulated E. coli O157:H7rif in different quantities, with the most significant accumulation being in the nut (collar) that attaches the die to the blade. This study determined specific distribution patterns of E. coli O157:H7rif after the grinding of a contaminated beef trim along with uncontaminated trims, and the results indicate that the grinding operation should be regarded as a means of distribution of microbial contamination in risk analyses of ground beef operations.

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Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Journal of Waste Management ◽

10.1155/2016/2717304 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Wilson Greya ◽

Bernard Thole ◽

Catherine Anderson ◽

Flavius Kamwani ◽

Jan Spit ◽

...

Keyword(s):

Large Scale ◽

Buffer Capacity ◽

Hydrated Lime ◽

Field Trials ◽

Small Scale ◽

E Coli ◽

Scale Field ◽

Large Scale Field ◽

Sanitation Systems ◽

Faecal Sludge

Off-site lime stabilisation for treating faecal sludge was assessed by undertaking small-scale (35 L) and large-scale (600 L) field trials in Blantyre, Malawi. Hydrated lime was dosed to maintain pH 10, pH 10.5, pH 11, pH 11.5, and pH 12 depending on the buffer capacity of the faecal sludge in the four replica small-scale field trials. Significant reduction of E. coli to below the detection limit of 104 CFU/100 mL within 1 hour of treatment was reported for pH > 11. Based on the small-scale findings, large-scale field trials were conducted and greater than 3 log removal of E. coli was observed under pH 12 conditions. Therefore, based on the study, off-site lime stabilisation by dosing lime in the range of 10–35% w/w (dry solid basis), depending on the buffer capacity and solids content of the sludge to maintain pH > 11, can be used to sanitise faecal sludge during emergencies, as well as for existing on-site sanitation systems.

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Community-based wastewater treatment systems and water quality of an Indonesian village

Journal of Water and Health ◽

10.2166/wh.2013.003 ◽

2013 ◽

Vol 12 (1) ◽

pp. 196-209 ◽

Cited By ~ 1

Author(s):

H. S. Lim ◽

L. Y. Lee ◽

S. E. Bramono

Keyword(s):

Water Quality ◽

Wastewater Treatment ◽

Chemical Oxygen Demand ◽

Total Nitrogen ◽

Oxygen Demand ◽

Small Scale ◽

Irrigation Canals ◽

Community Based ◽

E Coli ◽

The Impact

This paper examines the impact of community-based water treatment systems on water quality in a peri-urban village in Yogyakarta, Indonesia. Water samples were taken from the wastewater treatment plants (WWTPs), irrigation canals, paddy fields and wells during the dry and wet seasons. The samples were tested for biological and chemical oxygen demand, nutrients (ammonia, nitrate, total nitrogen and total phosphorus) and Escherichia coli. Water quality in this village is affected by the presence of active septic tanks, WWTP effluent discharge, small-scale tempe industries and external sources. We found that the WWTPs remove oxygen-demanding wastes effectively but discharged nutrients, such as nitrate and ammonia, into irrigation canals. Irrigation canals had high levels of E. coli as well as oxygen-demanding wastes. Well samples had high E. coli, nitrate and total nitrogen levels. Rainfall tended to increase concentrations of biological and chemical oxygen demand and some nutrients. All our samples fell within the drinking water standards for nitrate but failed the international and Indonesian standards for E. coli. Water quality in this village can be improved by improving the WWTP treatment of nutrients, encouraging more villagers to be connected to WWTPs and controlling hotspot contamination areas in the village.

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Preliminary assessment of small scale bacterial depuration of Crassostrea gigas and Anadara spp., Gulf of Nicoya, Costa Rica

Revista Ciencias Marinas y Costeras ◽

10.15359/revmar.5.7 ◽

2013 ◽

Vol 5 ◽

pp. 107

Author(s):

Luis A. Vega Corrales ◽

Carolina Marín Vindas ◽

Oscar Pacheco Prieto ◽

Gerardo Zúñiga Calero

Keyword(s):

Escherichia Coli ◽

Costa Rica ◽

Crassostrea Gigas ◽

Vibrio Parahaemolyticus ◽

Pathogenic Bacteria ◽

Small Scale ◽

Bivalve Molluscs ◽

Salmonella Spp ◽

E Coli ◽

Gulf Of Nicoya

Bivalve molluscs are sold without any sanitary control in Costa Rica, which represents a public health risk dueto the possible accumulation of pathogenic bacteria. Small scale bacterial depuration treatments were preliminarilyevaluated on Crassostrea gigas and Anadara spp. from the Gulf of Nicoya, Costa Rica, through the useof a recirculating system with UV irradiation. The levels of Escherichia coli in the water were determined usingthe MPN method. The MPN of E. coli and the presence of Salmonella spp., Vibrio parahaemolyticus and V. cholerae were determined in molluscs. Results confirm the effectiveness of the E. coli depuration system designin C. gigas and Anadara spp. The MPN of E. coli in the molluscs was reduced between 79% and 100% after 24h. None of the other types of bacteria were found in the samples analyzed. This is the first C. gigas depurationstudy in Costa Rica and the first report concerning UV depuration for bacterial indicators of fecal contaminationin Anadara spp. This research serves as a basis for the implementation and improvement of mollusc purification conditions in the country. It is recommended to monitor extraction and harvesting areas, as well as to implement the depuration of bivalve molluscs so that traditional producers can offer an innocuous product with added value.Los moluscos bivalvos son comercializados sin ningún control sanitario en Costa Rica; por tanto, representan un riesgo para la salud pública, debido a que pueden acumular bacterias patógenas. Se evaluaron preliminarmente tratamientos para la depuración bacteriana a pequeña escala de Crassostrea gigas y Anadara spp. en el Golfo de Nicoya, Costa Rica, utilizando un sistema recirculado e irradiado con luz UV. Los niveles de Escherichia coli en el agua se determinaron mediante el método del NMP. A los moluscos se les determinó el NMP de E. coli y la presencia de Salmonella spp., Vibrio parahaemolyticus y V. cholerae. Los resultados confirman la efectividad del diseño del sistema para la depuración de E. coli en C. gigas y Anadara spp. A las 24 h, el NMP de E. coli en los moluscos se redujo entre el 79% y el 100%. No se comprobó la presencia de las demás bacterias en las muestras analizadas. Este es el primer estudio sobre depuración de C. gigas en Costa Rica y el primer reporte de depuración con UV de indicadores bacterianos de contaminación fecal en Anadara spp. Este trabajo sirve de base para implementar y mejorar las condiciones de la depuración de moluscos en el país. Se recomienda monitorear las áreas de extracción y cultivo e implementar la depuración de los moluscos bivalvos para que los productores artesanales puedan ofrecer un producto inocuo y con valor agregado.

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Determining the Rate of Development of Antibiotic Resistance to Streptomycin and Doxycycline in Escherichia coli

Sciential - McMaster Undergraduate Science Journal ◽

10.15173/sciential.v1i3.2265 ◽

2019 ◽

pp. 2-7

Author(s):

Dominique Tertigas ◽

Gemma Barber

Keyword(s):

Escherichia Coli ◽

Antibiotic Resistance ◽

Combination Treatment ◽

Bacterial Resistance ◽

Cross Resistance ◽

Resistant Bacteria ◽

Small Scale ◽

Rate Of Development ◽

E Coli ◽

Successive Generations

Antibiotic resistance is a pressing issue in the medical field today. It is important to understand the development of bacterial resistance to implement effective preventative measures against antibiotic resistant bacteria. This study investigated the rate at which Escherichia coli (E. coli), a common pathogen, developed resistance to streptomycin and doxycycline, as Oz et al. (2014) showed differing levels of resistance in E. coli to these two antibiotics. The development of antibiotic resistance was measured by adding E. coli to 96-well plates in the presence of increasing doses of doxycycline, streptomycin, or a combination treatment. Successive generations were added to the same treatments to see whether they would grow at higher concentrations of antibiotic. The change in minimum inhibitory concentration for streptomycin and doxycycline was determined as the bacteria became increasingly resistant to each antibiotic. The fastest rate of antibiotic resistance was observed for streptomycin, with doxycycline resistance exhibiting a slower rate of development. The rate of resistance development for the combination treatment was the slowest, potentially due to small differences in target domains. Some cross-resistance was also observed. This study provides a small-scale methodological basis and preliminary insight on antibiotic resistance trends for two antibiotic classes and a combination treatment.

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Field Trial of an Automated Batch Chlorinator System at Two Shared Shallow Tubewells among Camps for Forcibly Displaced Myanmar Nationals (FDMN) in Cox’s Bazar, Bangladesh

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph182412917 ◽

2021 ◽

Vol 18 (24) ◽

pp. 12917

Author(s):

Nuhu Amin ◽

Mahbubur Rahman ◽

Mahbub-Ul Alam ◽

Abul Kasham Shoab ◽

Md. Kawsar Alome ◽

...

Keyword(s):

Field Trial ◽

Iron Concentration ◽

Small Scale ◽

Treatment Technology ◽

Treated Water ◽

E Coli ◽

Safe Storage ◽

Before And After ◽

Storage Containers ◽

Iron Concentrations

Chlorination of shallow tubewell water is challenging due to various iron concentrations. A mixed-method, small-scale before-and-after field trial assessed the accuracy and consistency of an automated chlorinator, Zimba, in Rohingya camp housing, Cox’s Bazar. From August–September 2018, two shallow tubewells (iron concentration = 6.5 mg/L and 1.5 mg/L) were selected and 20 households were randomly enrolled to participate in household surveys and water testing. The field-team tested pre-and post-treated tubewell and household stored water for iron, free and total chlorine, and E. coli. A sub-set of households (n = 10) also received safe storage containers (5 L jerry cans). Overall mean iron concentrations were 5.8 mg/L in Zimba water, 1.9 mg/L in household storage containers, and 2.8 mg/L in the project-provided safe storage containers. At baseline, 0% samples at source and 60% samples stored in household vessels were contaminated with E. coli (mean log10 = 0.62 MPN/100 mL). After treatment, all water samples collected from source and project-provided safe storage containers were free from E. coli, but 41% of post-treated water stored in the household was contaminated with E. coli. E. coli concentrations were significantly lower in the project-provided safe storage containers (log10 mean difference = 0.92 MPN, 95% CI = 0.59–1.14) compared with baseline and post-treated water stored in household vessels (difference = 0.57 MPN, 95% CI = 0.32–0.83). Zimba is a potential water treatment technology for groundwater extracted through tubewells with different iron concentrations in humanitarian settings.

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Variation of Total Coliforms and Bacteria during Dry and Wet Seasons in Rivers of Sigor Division, West Pokot County, Kenya

Journal of Advances in Microbiology ◽

10.9734/jamb/2020/v20i1130299 ◽

2020 ◽

pp. 41-51

Author(s):

Nyasimi Ayora Gershom ◽

Kirui Stella ◽

Maingi John ◽

Kebira Anthony

Keyword(s):

Small Scale ◽

Human Consumption ◽

Wet Season ◽

Biochemical Tests ◽

E Coli ◽

Urinary Infections ◽

Shigella Species ◽

West Pokot ◽

Dry Seasons ◽

Small Scale Farmers

Aims: There has been an increase in gastro-intestinal and urinary infections in Sigor division, West Pokot, Kenya. These infections result from bacteria and coliforms which are majorly propagated in water systems. Residents of this area are pastoralists and small-scale farmers relying on river water for their consumption and economic needs. This study aimed at characterizing the strains and quantities of bacteria and coliforms in the four rivers during the wet and dry seasons. Study Design: An independent measures design was used. Place and Duration of Study: Samples were taken from four rivers (Weiwei, Chesogon, Lomut and Muruny) in Sigor division, West Pokot county, Kenya. The study was conducted between January and October 2013. Methodology: Sampling was done at various points of the river in a stratified manner for characterization and analysis. Four main pathogens namely E. coli, V. cholerae, Shigella and Salmonella species as well as F. streptococci were isolated, cultured using different media and characterized. Further biochemical tests were conducted to confirm the exact strains present. Total viable counts for the bacteria and coliforms were then enumerated. Results: The results found out that E. coli, V. cholerae, Salmonella and Shigella species were abundant in the rivers while F. streptococci were only observed during the wet season. Biochemical tests conducted on the isolates revealed that the strains co-existed in the water samples. Weiwei river had the greatest number of bacteria strains. Muruny river was found to have the largest population of bacteria colony forming units (cfu’s). There was a large disparity in cfu’s in the rivers during the dry seasons. Chesogon river had the highest population of coliform units. Conclusion: The raw water in all the rivers were concluded to be unsafe for human consumption according to WHO standards.

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Optimization of Phosphate Limited Autoinduction Broth for 2-Stage Heterologous Protein Expression in E. coli

10.1101/2021.06.08.447502 ◽

2021 ◽

Author(s):

Romel Menacho-Melgar ◽

Jennifer N Hennigan ◽

Michael D Lynch

Keyword(s):

Protein Expression ◽

Small Scale ◽

Heterologous Protein Expression ◽

Scale Production ◽

Inducible Promoters ◽

E Coli ◽

Media Formulation ◽

Microtiter Plates ◽

Shake Flasks ◽

Consistent Performance

Autoinducible, 2-stage protein expression leveraging phosphate inducible promoters has been recently shown to enable not only high protein titers but also consistent performance across scales from screening systems (microtiter plates) to instrumented bioreactors. However, to date small scale production using microtiter plates and shake flasks rely on a complex autoinduction broth (AB) that requires making numerous media components, not all amenable to autoclaving. In this report, we develop a simpler media formulation (AB-2) with just a few autoclavable components. We show that AB-2 is robust to small changes in its composition and performs equally, if not better, than AB across different scales. AB-2 will facilitate adoption of phosphate limited 2-stage protein expression protocols.

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Treatment of anaerobically treated domestic wastewater using rotating biological contactor

Water Science & Technology ◽

10.2166/wst.2002.0371 ◽

2002 ◽

Vol 45 (10) ◽

pp. 371-376 ◽

Cited By ~ 13

Author(s):

A. Tawfik ◽

B. Klapwijk ◽

F. El-Gohary ◽

G. Lettinga

Keyword(s):

Domestic Wastewater ◽

Ammonia Concentration ◽

Ammonia Removal ◽

Uasb Reactor ◽

Small Scale ◽

E Coli ◽

Stage System ◽

Stage 1 ◽

Final Effluent ◽

Post Treatment Process

A small-scale pilot plant consisting of a three-stage RBC has been investigated for the removal of E. coli, COD fractions and ammonia from the effluent of an UASB reactor treating domestic wastewater. The results obtained reveal that a three-stage system operated at a HRT of 3.0 h represents an effective post-treatment process. The remaining COD in the final effluent was only 51 (± 7) mgl−1. Ammonia concentration was reduced by 67 (± 7.6) %. The overall E. coli reduction was 1.39 log10 at an influent count of 6.5 log10 corresponding to an overall removal efficiency of 95.8 (± 4.7) %. However, according to prevailing standards, residual E. coli counts are still high for unrestricted reuse for irrigation purposes. When the system was operated at a HRT of 10 h, overall E. coli removal and ammonia reduction were 99.9 (± 0.05)% and 92 (± 6.5)% respectively. At a HRT of 10 h, recirculation of the 3rd stage effluent to the 1st stage reduced the residual of E. coli in the final effluent from 2 × 103 to 9.8 × 102/100ml. Moreover, the recirculation of nitrified effluent from the 3rd stage to the 1st stage increased ammonia removal in the stage 1 from 23 to 43%. This relatively high ammonia removal likely can be attributed to the supply of nitrifiers from 3rd stage to the 1st one.

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