scholarly journals The effect of indoor daylight spectrum and intensity on viability of indoor pathogens on different surface materials

2022 ◽  
Author(s):  
Man In Lam ◽  
Kinga Vojnits ◽  
Michael Zhao ◽  
Sepideh Pakpour ◽  
Piers Macnaughton
Keyword(s):  
Growth Rate ◽  
Pathogenic Bacteria ◽  
Light Exposure ◽  
Fungal Growth ◽  
Built Environments ◽  
Rate Reduction ◽  
Bacterial Growth Rate ◽  
Surface Materials ◽  
Bacteria And Fungi ◽  
Ventilation Rates

Built environments play a key role in the transmission of infectious diseases. Ventilation rates, air temperature and humidity affect airborne transmission while cleaning protocols, material properties and light exposure can influence viability of pathogens on surfaces. We investigated how indoor daylight intensity and spectrum through electrochromic (EC) windows can impact the growth rate and viability of indoor pathogens on different surface materials (polyvinyl chloride (PVC) fabric, polystyrene (PS), and glass) compared to traditional blinds. Our results showed that tinted EC windows let in higher energy, shorter wavelength daylight than those with clear window and blind. The growth rates of pathogenic bacteria and fungi were significantly lower in spaces with EC windows compared to blinds: nearly 100% growth rate reduction was observed when EC windows were in their clear state followed by 41-100% reduction in bacterial growth rate and 26-42% reduction in fungal growth rate when EC windows were in their darkest tint. Moreover, bacterial viabilities were significantly lower on PVC fabric when they were exposed to indoor light at EC-tinted window. These findings are deemed fundamental to the design of healthy modern buildings, especially those that encompass sick and vulnerable individuals.

Review and synthesis of experimental data on organic matter decomposition with respect to the effect of temperature, moisture, and acidity

1998 ◽  
Vol 6 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Charlotta Walse ◽  
Björn Berg ◽  
Harald Sverdrup
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Organic Matter ◽  
Soil Moisture ◽  
Mass Loss ◽  
Growth Rates ◽  
Fungal Growth ◽  
Effect Of Temperature ◽  
Decomposition Model ◽  
Bacteria And Fungi

A review and synthesis of experimental decomposition data was performed with the objective of finding parameter values for a decomposition model. Experimental data were retrieved from the literature and included data on mass loss rates, nitrogen mineralization rates, carbon dioxide evolution rates, and growth rates of bacteria and fungi. Environmental variables included in the synthesis were air temperature, soil moisture, and soil acidity (concentration of H+ and Al3+ in soil solution). The variables were assumed to act as separate, multiplicative rate regulating factors on soil microbial processes. The model outline includes four organic matter pools: (i) easily decomposable compounds, (ii) holocellulose, (iii) lignin, and (iv) resistant compounds. It was assumed that the decomposition of the easily decomposable substances can be modeled as the growth rate of bacteria, while the decomposition of lignin and resistant compounds can be modeled as the growth rate of fungi. The decomposition of the substances included in the holocellulose pool was assumed to follow an intermediate function. Results show that enough data are available for the parameterization of a model of the suggested type. The effect of temperature on decomposition rate seems to increase with decreasing nutrient concentration of the substrate. Decomposition rates increase with relative soil moisture saturation. Bacterial growth rates are generally more sensitive to low pH than fungal growth rates. Decomposition of mixed organic material is inhibited in an intermediate fashion. The combined impact of H+ and Al3+ on the growth rates of bacteria and fungi can be modeled with an ion-exchange expression, preferably the Vanselow expression. It was concluded that some additional experiments would be needed for further model development purposes. Such experiments should be set up as mass loss experiments and last for a minimum of 2 weeks.Key words: decomposition, model, acidification, aluminum, pH.

Probiotics Slow the Growth of Pathogenic Bacteria

2019 ◽  
Vol 14 (1) ◽  
pp. 28-31 ◽  
Author(s):  
Rowles H. L.
Keyword(s):  
Growth Rate ◽  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Diarrheal Disease ◽  
Growth Curves ◽  
Mortality Rates ◽  
Controlled Delivery ◽  
E Coli ◽  
Multiple Strains ◽  
Commercial Probiotics

Probiotics are live microorganisms, which when ingested in sufficient amounts, confer health benefits to the host by improving the gut microflora balance. The purpose of this research was to determine whether commercial probiotic products containing multitude of commensal bacteria would reduce the growth rate of pathogenic bacteria, specifically Escherichia coli and Salmonella typhimurium. Growth curves were established, and the growth rates were compared for samples of E. coli, S. typhimurium, Nature’s Bounty Controlled Delivery probiotic, Sundown Naturals Probiotic Balance probiotic, and cocultures of the pathogenic bacteria mixed with the probiotics. The findings of this research were that the commercial probiotics significantly reduced the growth rate of E. coli and S. typhimurium when combined in cocultures. Probiotics containing multiple strains may be taken prophylactically to reduce the risk of bacterial infections caused by E. coli and S. typhimurium. Probiotics could be used to reduce the high global morbidity and mortality rates of diarrheal disease.

Oscillating conditions for influencing the composition of mixed biological cultures

1998 ◽  
Vol 37 (4-5) ◽  
pp. 259-262 ◽  
Author(s):  
Bjarne R. Horntvedt ◽  
Morten Rambekk ◽  
Rune Bakke
Keyword(s):  
Growth Rate ◽  
Specific Growth ◽  
Heterotrophic Bacteria ◽  
Bacterial Species ◽  
Rate Reduction ◽  
Similar Strategy ◽  
Sinusoidal Oscillations ◽  
Specific Growth Rates ◽  
Rate Limiting ◽  
Concentration Levels

This paper presents a strategy in which mixed biological cultures are exposed to oscillating concentration levels, to improve the potential for coexistence of desired bacterial species. A mechanistic mathematical model is constructed to investigate and illustrate this strategy. This paper is focused on competition between nitrifying, denitrifying and aerobic heterotrophic bacteria in a CSTR with sludge recycle. For nitrifying and aerobic heterotrophic cultures, the effect of sinusoidal oscillations in DO levels with an amplitude of 1.0 mg/l is a 16% specific growth rate reduction compared to that at a constant DO level. The denitrifiers growth rate is increased by an average of 59%, compared to the constant DO level situation. A similar strategy has been tested in a pilot plant. It is concluded that the influence on specific growth rates is a function of the amplitude of the oscillations. The effects are greatest when concentrations fluctuate around the half saturation concentration of the rate limiting component(s).

scholarly journals Simplified Approach to Predict Food Safety through the Maximum Specific Bacterial Growth Rate as Function of Extrinsic and Intrinsic Parameters

2021 ◽  
Vol 5 (2) ◽  
pp. 22
Author(s):  
Pedro D. Gaspar ◽  
Joel Alves ◽  
Pedro Pinto
Keyword(s):  
Growth Rate ◽  
Food Safety ◽  
Information And Communication Technologies ◽  
Bacterial Growth ◽  
Low Cost ◽  
Extrinsic Factors ◽  
Bacterial Growth Rate ◽  
Modeling Tools ◽  
Simplified Approach ◽  
Food Safety And Quality

Currently, we assist the emergence of sensors and low-cost information and communication technologies applied to food products, in order to improve food safety and quality along the food chain. Thus, it is relevant to implement predictive mathematical modeling tools in order to predict changes in the food quality and allow decision-making for expiration dates. To perform that, the Baranyi and Roberts model and the online tool Combined Database for Predictive Microbiology (Combase) were used to determine the factors that define the growth of different bacteria. These factors applied to the equation that determines the maximum specific growth rate establish a relation between the bacterial growth and the intrinsic and extrinsic factors that define the bacteria environment. These models may be programmed in low-cost wireless biochemical sensor devices applied to packaging and food supply chains to promote food safety and quality through real time traceability.

scholarly journals Seasonal Variation Characteristics of Bacteria and Fungi in PM2.5 in Typical Basin Cities of Xi’an and Linfen, China

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 809
Author(s):  
Sen Wang ◽  
Wanyu Liu ◽  
Jun Li ◽  
Haotian Sun ◽  
Yali Qian ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Relative Abundance ◽  
Pathogenic Bacteria ◽  
High Throughput Sequencing ◽  
Fine Particulate Matter ◽  
Ecological Functions ◽  
Factors Affecting ◽  
Bacterial Phyla ◽  
Variation Characteristics ◽  
Bacteria And Fungi

Microorganisms existing in airborne fine particulate matter (PM2.5) have key implications in biogeochemical cycling and human health. In this study, PM2.5 samples, collected in the typical basin cities of Xi’an and Linfen, China, were analyzed through high-throughput sequencing to understand microbial seasonal variation characteristics and ecological functions. For bacteria, the highest richness and diversity were identified in autumn. The bacterial phyla were dominated by Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes. Metabolism was the most abundant pathway, with the highest relative abundance found in autumn. Pathogenic bacteria (Pseudomonas, Acinetobacter, Serratia, and Delftia) were positively correlated with most disease-related pathways. Besides, C cycling dominated in spring and summer, while N cycling dominated in autumn and winter. The relative abundance of S cycling was highest during winter in Linfen. For fungi, the highest richness was found in summer. Basidiomycota and Ascomycota mainly constituted the fungal phyla. Moreover, temperature (T) and sulfur dioxide (SO2) in Xi’an, and T, SO2, and nitrogen dioxide (NO2) in Linfen were the key factors affecting microbial community structures, which were associated with different pollution characteristics in Xi’an and Linfen. Overall, these results provide an important reference for the research into airborne microbial seasonal variations, along with their ecological functions and health impacts.

scholarly journals Precise regulation of the relative rates of surface area and volume synthesis in bacterial cells growing in dynamic environments

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Handuo Shi ◽  
Yan Hu ◽  
Pascal D. Odermatt ◽  
Carlos G. Gonzalez ◽  
Lichao Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Time Delay ◽  
Surface Area ◽  
Environmental Changes ◽  
Volume Ratio ◽  
Dynamic Environments ◽  
Bacterial Cells ◽  
Bacterial Growth Rate ◽  
State Size ◽  
Insight Into

AbstractThe steady-state size of bacterial cells correlates with nutrient-determined growth rate. Here, we explore how rod-shaped bacterial cells regulate their morphology during rapid environmental changes. We quantify cellular dimensions throughout passage cycles of stationary-phase cells diluted into fresh medium and grown back to saturation. We find that cells exhibit characteristic dynamics in surface area to volume ratio (SA/V), which are conserved across genetic and chemical perturbations as well as across species and growth temperatures. A mathematical model with a single fitting parameter (the time delay between surface and volume synthesis) is quantitatively consistent with our SA/V experimental observations. The model supports that this time delay is due to differential expression of volume and surface-related genes, and that the first division after dilution occurs at a tightly controlled SA/V. Our minimal model thus provides insight into the connections between bacterial growth rate and cell shape in dynamic environments.

scholarly journals Antimicrobial Activities of Marine Sponge-Associated Bacteria

2021 ◽  
Vol 9 (1) ◽  
pp. 171
Author(s):  
Yitayal S. Anteneh ◽  
Qi Yang ◽  
Melissa H. Brown ◽  
Christopher M. M. Franco
Keyword(s):  
Pathogenic Bacteria ◽  
South Australia ◽  
Multidrug Resistant ◽  
Antimicrobial Activities ◽  
Marine Sponges ◽  
Bioactive Metabolites ◽  
Human Pathogens ◽  
Sponge Associated Bacteria ◽  
Microbial Symbionts ◽  
Bacteria And Fungi

The misuse and overuse of antibiotics have led to the emergence of multidrug-resistant microorganisms, which decreases the chance of treating those infected with existing antibiotics. This resistance calls for the search of new antimicrobials from prolific producers of novel natural products including marine sponges. Many of the novel active compounds reported from sponges have originated from their microbial symbionts. Therefore, this study aims to screen for bioactive metabolites from bacteria isolated from sponges. Twelve sponge samples were collected from South Australian marine environments and grown on seven isolation media under four incubation conditions; a total of 1234 bacterial isolates were obtained. Of these, 169 bacteria were tested in media optimized for production of antimicrobial metabolites and screened against eleven human pathogens. Seventy bacteria were found to be active against at least one test bacterial or fungal pathogen, while 37% of the tested bacteria showed activity against Staphylococcus aureus including methicillin-resistant strains and antifungal activity was produced by 21% the isolates. A potential novel active compound was purified possessing inhibitory activity against S. aureus. Using 16S rRNA, the strain was identified as Streptomyces sp. Our study highlights that the marine sponges of South Australia are a rich source of abundant and diverse bacteria producing metabolites with antimicrobial activities against human pathogenic bacteria and fungi.

Sign in / Sign up

Export Citation Format

Share Document