PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 1804461

Global stability in a synthrophic chain model.

A S Elkhader
View original source ↗Export metadata ↓

Abstract

A mathematical model formulated by G. Powell in 1986 is considered. This model describes a synthrophic chain of species Xi, 1 less than or equal to i less than or equal to n, in a continuous chemostat culture. Species Xi utilizes substrate Si and forms a product Si + 1. Substrate Si + 1 inhibits the growth of Xi and constitutes a growth-limiting substrate of Xi + 1. For this model, the conditions for coexistence of all species are improved, and the local stability results are extended to global stability. Some interesting cases are discussed.

Explore related subjects

Gram-Negative BacteriaKineticsMathematicsModels, BiologicalPseudomonasJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

A S Elkhader. 1991. Global stability in a synthrophic chain model.. https://doi.org/10.1016/0025-5564(91)90062-n

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2006

Multidrug-resistant endosymbiotic bacteria account for the emergence of zygomycosis: A hypothesis.

Although the extensive use of Aspergillus-active antifungals has been recently associated with an increase in zygomycosis in several cancer centers, the frequency of this opportunistic mycosis began to rise earlier, since the mid 1990s. The reasons for that emergence are unclear. Recent evidence suggests that endosymbiotic bacteria of Rhizopus species produce toxins that enhance fungal pathogenicity. We postulate that, although Zygomycetes appear equally ubiquitous and virulent to Aspergillus, zygomycosis was rare in the past in immunosuppressed patients specifically because of the widespread use of antibacterials in this patient population. Such use may have resulted in inhibition of endosymbiotic, toxin-producing bacteria and led indirectly in attenuation of Zygomycetes virulence. Thus, the growing rates of antimicrobial resistance over the past decade selected for multidrug-resistant endosymbiotic bacteria of Zygomycetes, which could facilitate the emergence of zygomycosis. This hypothesis, if true, will be the first paradigm of modulation of virulence of opportunistic fungi by antibacterials.

Gram-Negative Bacteria↗
PubMed2006

Serum amyloid A is an innate immune opsonin for Gram-negative bacteria.

Serum amyloid A (SAA) is the major acute-phase protein in man and most mammals. Recently we demonstrated that SAA binds to many Gram-negative bacteria including Escherichia coli and Pseudomonas aeruginosa through outer membrane protein A (OmpA) family members. Therefore we investigated whether SAA altered the response of innate phagocytic cells to bacteria. Both the percentage of neutrophils containing E coli and the number of bacteria per neutrophil were greatly increased by SAA opsonization, equivalent to the increase seen for serum opsonization. In contrast, no change was seen for Streptococcus pneumoniae, a bacteria that did not bind SAA. Neutrophil reactive oxygen intermediate production in response to bacteria was also increased by opsonization with SAA. SAA opsonization also increased phagocytosis of E coli by peripheral blood mononuclear cell-derived macrophages. These macrophages showed strong enhancement of TNF-alpha and IL-10 production in response to SAA-opsonized E coli and P aeruginosa. SAA did not enhance responses in the presence of bacteria to which it did not bind. These effects of SAA occur at normal concentrations consistent with SAA binding properties and a role in innate recognition. SAA therefore represents a novel innate recognition protein for Gram-negative bacteria.

Gram-Negative Bacteria↗