We examine the conditions necessary for the emergence of complex dynamic behavior in systems of microbial competition. In particular, we study the effect of spatial heterogeneity and substrate-inhibition on the dynamics of such a system. This is accomplished through the study of a mathematical model of two microbial populations competing for a single nutrient in a configuration of two interconnected chemostats. Microbial growth is assumed to follow substrate-inhibited kinetics for both species. Such a system with sterile feed has been shown in a previous work to exhibit stable periodic states. In the present work we study the system for the case of non-sterile feed, i.e., when the two species are present in the feed of the chemostats. The analysis is done by numerical bifurcation theory methods. We demonstrate that, in addition to periodic states, the system possesses stable quasi-periodic states resulting from Neimark-Sacker bifurcations of limit cycles. Also, periodic states may undergo successive period doublings leading to periodic states of increasing period and indicating that chaotic states might be possible. Multistability is also observed, consisting in the coexistence of several stable steady states and possibly stable periodic or quasi-periodic states for given operating conditions. It appears that substrate-inhibition, spatial heterogeneity and presence of microorganisms in the inflow are all necessary conditions for complex dynamics to arise in a microbial system of pure and simple competition.
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http://dx.doi.org/10.1016/j.jbiotec.2008.08.006 | DOI Listing |
Electrophoresis
January 2025
Institute of Forensic Science, Fudan University, Shanghai, P. R. China.
The human skin and oral cavity harbor complex microbial communities, which exist in dynamic equilibrium with the host's physiological state and the external environment. This study investigates the microbial atlas of human skin and oral cavities using samples collected over a 10-month period, aiming to assess how both internal and external factors influence the human microbiome. We examined bacterial community diversity and stability across various body sites, including palm and nasal skin, saliva, and oral epithelial cells, during environmental changes and a COVID-19 pandemic.
View Article and Find Full Text PDFTrop Med Health
January 2025
School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia.
Background: Oromia regional state experiencing cholera outbreaks in a protracted pattern despite various interventions at local and regional levels. This study aimed to examine the implementation of Risk Communication and Community Engagement (RCCE) activities for cholera outbreak control in the region.
Methods: We conducted a quantitative and qualitative mixed-method study.
Int J Equity Health
January 2025
Center for Health Equity in Latin America, Celia Scott Weatherhead School of Public Health and Tropical Medicine, Tulane University, Louisiana, USA.
Background: Ethnic and racial discrimination in maternal health care has been overlooked in academic literature and yet it is critical for achieving universal health coverage (UHC). There is a lack of empirical evidence on its impact on the effective coverage of maternal health interventions (ECMH) for Indigenous women in Mexico. Documenting progress in reducing maternal health inequities, particularly given the disproportionate impact of the Covid-19 pandemic on ethnic minorities, is essential to improving equity in health systems.
View Article and Find Full Text PDFAnal Chim Acta
February 2025
Dept. of Electronic Materials Engineering, Kwangwoon University, Seoul, 01897, Republic of Korea. Electronic address:
Background: Atrazine (ATZ), a pesticide that poses serious health problems, is observed in the environment, thereby prompting its periodic monitoring and control using functional biosensors. However, established methods for ATZ detection have limited applicability. Two-dimensional (2D) metal azolate frameworks (MAF) have a higher surface area per unit volume and provide easier access to active sites.
View Article and Find Full Text PDFJ Prev Alzheimers Dis
January 2025
Geriatrics Department, Fernand Widal Lariboisière University Hospital, GHU APHP.Nord, Paris, France; Paris-Cité University, Inserm U1144, Paris, France; Paris-Cité University, Inserm U1153, Paris, France.
Background: The use of cerebrospinal (CSF) biomarkers in the diagnosis of Alzheimer's disease (AD) has been gaining interest in clinical practice. Although their usefulness has been demonstrated, their potential value in older patients remains debated.
Objectives: To assess whether knowledge of the results of CSF AD biomarkers was associated with the same gain in diagnostic confidence in older adults > 80 than in younger patients.
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