A unifying hypothesis for the structure of microbial biofilms based on cellular automaton models

Wimpenny, J. W. T.; Colasanti, R. L.

doi:10.1111/j.1574-6941.1997.tb00351.x

Cited by 300 publications

(53 citation statements)

References 27 publications

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“…Mathematical models that capture spatial structure and stochastic effects down to the level of individuals have now been applied widely to various biological systems (Durrett & Levin, 1994a, b;Hanski & Gilpin, 1997;Tilman & Kareiva, 1997;Durrett & Levin, 1998;Dieckmann et al, 2000), including some that involve microbial communities (Durrett & Levin, 1997;Wimpenny & Colasanti, 1997;Kreft et al, 1998;Picioreanu et al, 1998aPicioreanu et al, , b, 2004Kerr et al, 2002;Kreft & Bonhoeffer, 2005;Wei & Krone, 2005;Xavier et al, 2005;Krone & Guan, 2006;Mochizuki et al, 2006). These individual-based lattice models are of several types.…”

Section: Introductionmentioning

confidence: 99%

Modelling the spatial dynamics of plasmid transfer and persistence

et al. 2007

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Bacterial plasmids are extra-chromosomal genetic elements that code for a wide variety of phenotypes in their bacterial hosts and are maintained in bacterial communities through both vertical and horizontal transfer. Current mathematical models of plasmid-bacteria dynamics, based almost exclusively on mass-action differential equations that describe these interactions in completely mixed environments, fail to adequately explain phenomena such as the long-term persistence of plasmids in natural and clinical bacterial communities. This failure is, at least in part, due to the absence of any spatial structure in these models, whereas most bacterial populations are spatially structured in microcolonies and biofilms. To help bridge the gap between theoretical predictions and observed patterns of plasmid spread and persistence, an individual-based lattice model (interacting particle system) that provides a predictive framework for understanding the dynamics of plasmid-bacteria interactions in spatially structured populations is presented here. To assess the accuracy and flexibility of the model, a series of experiments that monitored plasmid loss and horizontal transfer of the IncP-1b plasmid pB10 : : rfp in Escherichia coli K12 and other bacterial populations grown on agar surfaces were performed. The model-based visual patterns of plasmid loss and spread, as well as quantitative predictions of the effects of different initial parental strain densities and incubation time on densities of transconjugants formed on a 2D grid, were in agreement with this and previously published empirical data. These results include features of spatially structured populations that are not predicted by mass-action differential equation models.

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Section: Introductionmentioning

confidence: 99%

Modelling the spatial dynamics of plasmid transfer and persistence

et al. 2007

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“…3). Bacteria form a thick biofilm under rich nutrient conditions and a very thin biofilm under poor nutrient conditions (Wimpenny et al, 1997). For this reason, lack of nutrients can prevent P. putida from forming biofilm.…”

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confidence: 99%

Effects of Temperature and Nutrient Conditions on Biofilm Formation of Pseudomonas putida

Morimatsu

Eguchi

Hamanaka

et al. 2012

FSTR

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In this study, biofilm formation of Pseudomonas putida at a constant temperature of 5℃, 10℃, 20℃ or 30℃ under rich and poor nutrient conditions was investigated. For all temperature conditions, P. putida initially grew and formed biofilm. Subsequently, under the rich nutrient condition, the biofilm detached after it reached maturity at a high temperature, but those at a low temperature remained attached. In contrast, under the poor nutrient condition, biofilm detachment occurred regardless of the temperature condition; thus, lack of nutrients may cause biofilm detachment. Therefore, aside from cleaning blots and strict maintenance of a low temperature during the distribution of agricultural produce, attention must be paid to biofilm detachment as it can lead to an increased risk of bacterial contamination and food poisoning.Keywords: biofilm, bacterial attachment, biofilm detachment, Pseudomonas putida *To whom correspondence should be addressed. E-mail: toshiu@bpes.kyushu-u.ac.jp IntroductionIn recent years, it has been revealed that bacteria attached to food surfaces form biofilm, which is a structure formed by the production of amorphous extracellular polysaccharides that embed into the attached viable and dead cells. Zottola et al. (1994) observed that biofilm enhances the tolerance of microorganisms to sterilization by heat and chemical agents. Hence, the presence of biofilm-forming bacteria has received much attention as a problem related to food safety. Houdt et al. (2010) also highlighted the importance of understanding the microbial mechanism of biofilm formation in order to control problems caused by biofilm. Bacteria attach onto food surfaces and form biofilm during the food distribution process in which the food is exposed to a variety of environmental conditions. In practice, for the prevention of bacterial growth during the distribution of agricultural produce, nutrients available to the bacteria are restricted by cleaning blots from the surface of food (Simões et al., 2010), and the activity of these bacteria is reduced by strict maintenance of a low temperature (Ukuku et al., 2007). Thus, there have been many active studies on the single effect of environmental conditions related to the distribution of agricultural produce on biofilm formation in order to shed light on the mechanism of biofilm formation (Song et al., 2006;Sakuragi et al., 2007). However, in the actual distribution environment, plural environmental factors simultaneously affect bacterial biofilm formation, and there has not been enough research to clarify the multiple effects on biofilm formation. This study aimed to investigate the effect of temperature and nutrient conditions encountered during the actual food distribution process on biofilm formation by examining the amount of attached biofilm and the number of bacteria in biofilm grown at a variety of constant temperatures under rich and poor nutrient conditions. Materials and MethodsBacterial strains and growth conditions In this study, bacteria isolated from cucumber fruit w...

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“…For process optimization, the spatial distribution of the different types of microorganisms, and therefore the reactions in the biofilm, may be controlled by varying the operational conditions such as surface loading rate, upflow fluid velocity, and oxygen supply. Other studies also demonstrated the possible structural change of the biofilms as a result of the differences in the local substrate availability (33)(34)(35), or upflow fluid velocity outside the biofilm in the reactor (20). Future studies will be directed to further examine the influence of the operation parameters on the biofilm structures and functions for more effective treatment of organonitrile wastewater by the MABR technology.…”

Section: Resultsmentioning

confidence: 96%

Membrane-Aerated Biofilm Reactor for the Treatment of Acetonitrile Wastewater

Liu

Bai

et al. 2008

Environ. Sci. Technol.

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A membrane-aerated biofilm reactor (MABR) was studied for the treatment of wastewater containing acetonitrile, a typical organonitrile compound. The MABR used hydrophobic hollow fiber membranes as the diffusers for bubbleless aeration as well as the carriers for biofilm growth. The objectives were to prevent the stripping-loss of acetonitrile during aeration and to achieve acetonitrile biodegradation plus nitrogen removal simultaneously in a single biolfilm on the membranes. In the MABR, oxygen and substrates were supplied to the biofilm from opposite sides, in contrast to those from the same side in conventional biofilm bioreactors. Operational factors, including surface loading rate and upflow fluid velocity in the bioreactor, on the effect of acetonitrile biodegradation performance were examined. The profiles of dissolved oxygen concentration and microbial activities and populations in the biofilm were investigated. Experimental results showed that, with the adapted microorganisms, removal of acetonitrile at approximately 98.6 and 83.3%, in terms of total organic carbon and total nitrogen, were achieved at a surface loading rate (in terms of membrane surface) of up to 11.29 g acetonitrile/ m 2 · d with an upflow fluid velocity of 12 cm/s and a hydraulic retention time of 30 h. The biofilm on the membranes developed an average thickness of about 1.6 mm in the steady state and consisted of oxic/anoxic/anaerobic zones that provided different functions for acetonitrile degradation, nitrification, and denitrification. The acetonitrile-degrading bacteria in the MABR appeared to secrete more extracellular polymeric substances that enhanced the attachment and development of the biofilm on the membranes. The study demonstrated the potential of using the MABR for the treatment of organonitrile wastewater.

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A unifying hypothesis for the structure of microbial biofilms based on cellular automaton models

Cited by 300 publications

References 27 publications

Modelling the spatial dynamics of plasmid transfer and persistence

Modelling the spatial dynamics of plasmid transfer and persistence

Effects of Temperature and Nutrient Conditions on Biofilm Formation of Pseudomonas putida

Membrane-Aerated Biofilm Reactor for the Treatment of Acetonitrile Wastewater

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