Browsing by Author "Ayati, B. P."

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Models of microbial dormancy in biofilms and planktonic cultures
(2012) Ayati, B. P.; Klapper, Isaac
We present models of dormancy in planktonic cultures and in biofilm, and a new numerical technique for solving the model equations. We use this modeling framework to examine the relative advantage of short dormancy versus long dormancy times in planktonic cultures and biofilms under some basic assumptions. Simulations and asymptotic analyses indicate that in planktonic batch cultures and in chemostats, live biomass is maximized by the fastest possible exit from dormancy. The lower limit of time to reawakening is thus perhaps governed by physiological, biochemical, or other constraints within the cells. In biofilm we see, in contrast, that the slower waker may have an advantage over the faster waker.
A multiscale model of biofilm as a senescence-structured fluid
(2007-01) Ayati, B. P.; Klapper, Isaac
We derive a physiologically structured multiscale model for biofilm development. The model has components on two spatial scales, which induce different time scales into the problem. The macroscopic behavior of the system is modeled using growth-induced flow in a domain with a moving boundary. Cell-level processes are incorporated into the model using a so-called physiologically structured variable to represent cell senescence, which in turn affects cell division and mortality. We present computational results for our models which shed light on modeling the combined role senescence and the biofilm state play in the defense strategy of bacteria.
Senescence can explain microbial persistence
(2007-11) Klapper, Isaac; Gilbert, P.; Ayati, B. P.; Dockery, Jack D.; Stewart, Philip S.
It has been known for many years that small fractions of persister cells resist killing in many bacterial colony–antimicrobial confrontations. These persisters are not believed to be mutants. Rather it has been hypothesized that they are phenotypic variants. Current models allow cells to switch in and out of the persister phenotype. Here, a different explanation is suggested for persistence, namely senescence. Using a mathematical model including age structure, it is shown that senescence provides a natural explanation for persistence-related phenomena, including the observations that the persister fraction depends on growth phase in batch culture and dilution rate in continuous culture.