scholarly journals Investigating the effects of different physical and chemical stress factors on microbial biofilm

Water SA ◽  
2018 ◽  
Vol 44 (2 April) ◽  
Author(s):  
Cansu Vatansever ◽  
Irfan Turetgen
Keyword(s):  
Environmental Conditions ◽  
Cooling Tower ◽  
Solid Phase ◽  
Culture Technique ◽  
Stress Factors ◽  
Chemical Stress ◽  
Dapi Staining ◽  
Conventional Culture ◽  
Physical And Chemical ◽  
The Impact

Microorganisms that adhere to surfaces in order to protect themselves from many adverse environmental conditions form a layer called biofilm. Biofilms protect bacteria from changing environmental conditions such as starvation, antibiotics, disinfectants, pH and temperature fluctuation, dryness and UV rays. In this study, biofilms were formed on surfaces of glass coupons in a cooling tower model system over a period of 180 days. The biofilms were treated with various stress factors monthly. These stress factors were: exposure to temperatures of 4°C and 60°C, pH of 3, 5, and 11, 3 M aqueous NaCl and distilled water, as well as, monochloramine at 2, 500, and 1 000 mg/L (ppm). Following the treatment with stress factors, both the numbers of actively respiring bacteria and the total bacteria in the biofilms were determined by CTC-DAPI staining. The aerobic heterotrophic plate counts (HPC) in the biofilms were determined by the conventional culture method of spread plating on R2A agar. The aim of this study was to determine the impact of these stressors on the model cooling tower biofilms. Of the stressors tested, those that had the greatest impact were a temperature of 60°C, pH of 3, 3 M NaCl, and monochloramine at both 500 and 1 000 mg/L. However, when using a non-culture-based viability assay (CTC-DAPI staining), an extremely high number of live bacteria were detected even after applying the most effective stress factors (with the exception of pH 3) of 60°C, 3 M NaCl, monochloramine at 500 and 1 000 mg/L. Results showed that biofilm protects the bacteria from extreme physical and chemical stress conditions. Additionally, the conventional culture technique cannot detect the presence of bacteria that have entered the viable but non-culturable (VBNC) phase; the use of different techniques, such as microscopy and cytometry (flow and solid-phase), is therefore important to obtain more accurate results.

Effects of various stress factors on heat tolerance by Heterorhabditis bacteriophora and Steinernema carpocapsae

Nematology ◽  
2007 ◽  
Vol 9 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Anwar Bilgrami ◽  
Randy Gaugler
Keyword(s):  
Heat Tolerance ◽  
Environmental Conditions ◽  
Entomopathogenic Nematodes ◽  
Heterorhabditis Bacteriophora ◽  
Normal Function ◽  
Steinernema Carpocapsae ◽  
Stress Factors ◽  
Adverse Environmental Conditions ◽  
Physical And Chemical ◽  
Better Than

AbstractCentrifugation, desiccation, agitation, and handling of entomopathogenic nematodes in the laboratory during isolation, culture, storage, formulation and experimentation, influences nematode ability to tolerate adverse environmental conditions. Stress imposed by centrifugation (5-60 min), desiccation (3-9 days), agitation (3-24 h), and handling (2-10 times) reduced stress and heat tolerance in Heterorhabditis bacteriophora and Steinernema carpocapsae. Short durations of stresses (e.g., 5 min of centrifugation, 3-5 days of desiccation, 3 h of agitation and 2-4 times of handling) did not affect nematodes, whereas prolonged durations (e. g., 10-60 min of centrifugation, 7-9 days of desiccation, 6-24 h of agitation and 6-10 times of handling) significantly decreased heat tolerance. Steinernema carpocapsae tolerated stress comparatively better than H. bacteriophora by showing a significantly greater degree of heat tolerance. This study provides a basis to investigate further the effects of physical and chemical stresses in order to minimise handling of laboratory nematodes and reduce disruptions of their normal function and behaviour.

Short Communication: Variation in response to processing, in vitro gas production and fermentation of western Canadian feed barley

2014 ◽  
Vol 94 (4) ◽  
pp. 725-729 ◽  
Author(s):  
W. Z. Yang ◽  
M. Oba ◽  
M. L. Swift ◽  
T. A. McAllister
Keyword(s):  
Dry Matter ◽  
Short Communication ◽  
Nutrient Content ◽  
Culture Technique ◽  
Gas Production ◽  
Western Canada ◽  
In Vitro Gas Production ◽  
Physical And Chemical ◽  
The Impact

Yang, W. Z., Oba, M., Swift, M. L. and McAllister, T. A. 2014. Short Communication: Variation in response to processing, in vitro gas production and fermentation of western Canadian feed barley. Can. J. Anim. Sci. 94: 725–729. Sixty feed barley samples were collected from various locations in western Canada. Samples were either ground (1 mm) or dry-rolled to a processing index of 80%, and fermentability was assessed by measuring gas production (GP) and dry matter disappearances (DMD) at 0, 4, 8, 14 and 24 h of incubation using a batch culture technique. Physical and chemical composition, and GP and DMD varied substantially among samples. There were significant correlations among test weight and nutrient content of barley with GP and DMD of ground barley. The results indicate that the impact of nutrient content on in vitro DMD is more easily detected with ground than rolled barley.

Characterization of Solids in Residual Wastes from Underground Storage Tanks at the Hanford Site, Washington, U.S.A.

2006 ◽  
Vol 985 ◽  
Author(s):  
Kenneth Michael Krupka ◽  
William J. Deutsch ◽  
H. Todd Schaef ◽  
Bruce W. Arey ◽  
Steve M. Heald ◽  
...  
Keyword(s):  
Solid Phase ◽  
Chemical Characterization ◽  
Sem Analysis ◽  
Hanford Site ◽  
Characterization Methods ◽  
X Ray ◽  
Limited Series ◽  
Oxide Phases ◽  
Physical And Chemical ◽  
The Impact

AbstractSolid phase physical and chemical characterization methods have been used in an ongoing study of residual wastes from several single-shell underground waste tanks at the U.S. Department of Energy's Hanford Site in southeastern Washington State. Because these wastes are highly-radioactive dispersible powders and are chemically-complex assemblages of crystalline and amorphous solids that contain contaminants as discrete phases and/or co-precipitated within oxide phases, their detailed characterization offers an extraordinary technical challenge. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) are the two principal methods used, along with a limited series of analyses by synchrotron-based methods, to characterize solid phases and their contaminant associations in these wastes. Depending on the specific tank, numerous solids (e.g., èejkaite; Na2U2O7; clarkeite; gibbsite; böhmite; dawsonite; cancrinite; Fe oxides such as hematite, goethite, and maghemite; rhodochrosite; lindbergite; whewellite; nitratine; and several amorphous phases) have been identified in residual wastes studied to date. Because many contaminants of concern are heavy elements, SEM analysis using the backscattered electron (BSE) signal has proved invaluable in distinguishing phases containing elements, such as U and Hg, within the complex assemblage of particles that make up each waste. XRD, SEM/EDS, and synchrotron-based methods provide different, but complimentary characterization data about the morphologies, crystallinity, particle sizes, surface coatings, and compositions of phases in these wastes. The impact of these techniques is magnified when each is used in an iterative fashion to help interpret the results from the other analysis methods and identify additional, more focused analyses.

scholarly journals Phosphorus availability in the central area of the Argentine Pampean region. 1: Relationship between soil parameters, adsorption processes and wheat, soybean and corn yields in different soil and management environments .

2014 ◽  
Vol 2 ◽  
Author(s):  
Martín M. Silva Rossi ◽  
Omar A. Bachmeier ◽  
Adriana Ana del Carmen Rollán
Keyword(s):  
Soil Type ◽  
Crop Yields ◽  
Solid Phase ◽  
Central Area ◽  
Soil Parameters ◽  
Adsorption Parameters ◽  
Phosphorus Adsorption ◽  
Adsorption Processes ◽  
Physical And Chemical ◽  
The Impact

Retention of phosphorus in the soil solid phase is a complex process, caused by a combination of physical and chemical mechanisms that determine pools of compounds with different degrees of solubility. The amount of P available in a given pool can be associated with the adsorption maximum proposed by the Langmuir isotherm model, and with the energy with which it is retained. The aims of this work were: i) to evaluate the impact of the fertilization history and soil type on phosphorus adsorption parameters, and ii) to analyze the effect of soil properties, mainly the phosphorus adsorption parameters, on the yield of wheat, soybean and corn crops. In this study we established that the Bray & Kurtz 1 extractant is insufficiently sensitive for assessing changes in the nutrient availability when phosphorous concentrations are relatively low. The amount of phosphorus retained in the labile pool and its retention energy, however, are sensitive indicators of the availability of this nutrient. These indexes explain most of the variations in crop yields, and are determined more by P fertilization management than by soil type.

scholarly journals Pengaruh Keberadaan TPA terhadap Kualitas Air Bersih Diwilayah Pemukiman Warga Sekitar: Studi Literatur

2020 ◽  
Vol 20 (3) ◽  
pp. 1075
Author(s):  
Ahmad Walid ◽  
Raden Gamal Tamrin Kusumah ◽  
Erik Perdana Putra ◽  
Wira Herlina ◽  
Puji Suciarti
Keyword(s):  
Water Pollution ◽  
Environmental Conditions ◽  
Research Method ◽  
Clean Water ◽  
Ground Water Pollution ◽  
Surrounding Environment ◽  
Processing Site ◽  
Physical And Chemical ◽  
The Impact

The influence of the presence of landfill in the presence of pollution can occur in the air as a result of waste decomposition, can also pollute water and soil caused by leachate seepage. Piles of garbage can cause physical and chemical environmental conditions to be incompatible with normal conditions. This research method uses a study method literature by collecting data by looking for relevant references and facts to get an argumentative description of the effect of the landfill, the literature is filtered and connected to get conclusions to understand the impact of the presence of landfill on the quality of clean water in the surrounding environment. Results obtained and concluded cities which are stockpiled at the final processing site (TPA), have the potential to cause environmental pollution, both surface and ground water pollution and soil pollution due to leachate.

scholarly journals Elasmobranch Use of Nearshore Estuarine Habitats Responds to Fine-Scale, Intra-Seasonal Environmental Variation: Observing Coastal Shark Density in a Temperate Estuary Utilizing Unoccupied Aircraft Systems (UAS)

Drones ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 74
Author(s):  
Alexandra E. DiGiacomo ◽  
Walker E. Harrison ◽  
David W. Johnston ◽  
Justin T. Ridge
Keyword(s):  
Environmental Conditions ◽  
Spatial Scales ◽  
Shark Species ◽  
Rachel Carson ◽  
Generalized Linear Modelling ◽  
Aircraft System ◽  
Study Sites ◽  
Dynamic Habitat ◽  
Physical And Chemical ◽  
The Impact

Many coastal shark species are known to use estuaries of the coastal southeastern United States for essential purposes like foraging, reproducing, and protection from predation. Temperate estuarine landscapes, such as the Rachel Carson Reserve (RCR) in Beaufort, NC, are dynamic habitat mosaics that experience fluctuations in physical and chemical oceanographic properties on various temporal and spatial scales. These patterns in abiotic conditions play an important role in determining species movement. The goal of this study was to understand the impact of environmental conditions around the RCR on shark density within the high-abundance summer season. Unoccupied Aircraft System (UAS) surveys of coastal habitats within the reserve were used to quantify shark density across varying environmental conditions. A combination of correlation analyses and Generalized Linear Modelling (GLM) revealed that density differs substantially across study sites and increases with rising water temperatures, conclusions that are supported by previous work in similar habitats. Additionally, density appears to increase moving towards dawn and dusk, potentially supporting crepuscular activity in coastal estuarine areas. By describing shark density dynamics in the RCR, this study provides new information on this population and presents a novel framework for studying elasmobranchs in temperate estuaries.

Factors Influencing Academic Stress on Students of University of Economics and Business - Vietnam National University

2020 ◽  
Vol 36 (3) ◽  
Author(s):  
Nham Phong Tuan ◽  
Nguyen Ngoc Quy ◽  
Nguyen Thi Thanh Huyen ◽  
Hong Tra My ◽  
Tran Nhu Phu
Keyword(s):  
Academic Stress ◽  
Stress Factors ◽  
Negative Effects ◽  
Cross Sectional ◽  
Stress Scale ◽  
Perceptions And Attitudes ◽  
National University ◽  
Questionnaire Surveys ◽  
The University ◽  
The Impact

The objective of this study is to investigate the impact of seven factors causing academic stress on students of University of Economics and Business - Vietnam National University: Lack of leisure time, Academic performance, Fear of failure, Academic overload, Finances, Competition between students, Relationships with university faculty. Based on the results of a practical survey of 185 students who are attending any courses at the University of Economics and Business - Vietnam National University, the study assesses the impact of stress factors on students. The thesis focuses on clarifying the concept of "stress" and the stress level of students, while pointing out its negative effects on students. This study includes two cross-sectional questionnaire surveys. The first survey uses a set of 16 questions to assess students’ perceptions and attitudes based on an instrument to measure academic stress - Educational Stress Scale for Adolescents (ESSA). The second survey aims to test internal consistency, the robustness of the previously established 7-factor structure. Henceforth, the model was brought back and used qualitatively, combined with Cronbach’s Alpha measurement test and EFA discovery factor analysis. This study was conducted from October 2019 to December 2019. From these practical analyzes, several proposals were made for the society, the school and the students themselves.

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