Diffusion into microbial aggregates

Matson, Jack V.; Characklis, William G.

doi:10.1016/0043-1354(76)90022-1

Cited by 123 publications

(46 citation statements)

References 2 publications

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“…This confirms the work of Tatevossian (30) and Lens et al (13), who also found that glutaraldehyde and heat treatment significantly affects the transport properties of cell aggregates. In agreement with results reported by Matson and Characklis (21), deactivation of microbial metabolism by HgCl 2 did not alter the self-diffusion coefficient compared to that in untreated aggregates. Thus, HgCl 2 deactivation of aggregates can be recommended for measurement techniques of the diffusion coefficient that rely on biomass deactivation.…”

Section: Discussionsupporting

confidence: 82%

Diffusional Properties of Methanogenic Granular Sludge: ¹ H NMR Characterization

Lens

Gastesi

Vergeldt

et al. 2003

Appl Environ Microbiol

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The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H 2 O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H 2 O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl 2 did not affect the H 2 O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors.

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Section: Discussionsupporting

confidence: 82%

Diffusional Properties of Methanogenic Granular Sludge: ¹ H NMR Characterization

Lens

Gastesi

Vergeldt

et al. 2003

Appl Environ Microbiol

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“…Zhang and Bishop (2001) extended this work to the investigation of gradients of EPS, phospholipids and density in 11 week old biofilms and determined that the deeper, more dense, region of the biofilm contained more nonviable cells and less EPS, these findings suggested that the density gradient could be attributable to the accumulation of inert material. This is consistent with other work (Matson and Characklis, 1976, Horn and Hempel 1997, Telgmann, 2004 showing a decreasing (or at best steady) trend in substrate diffusion coefficients with increasing biomass age.…”

Section: Introductionsupporting

confidence: 93%

Tracer measurements reveal experimental evidence of biofilm consolidation

Casey

2007

Biotech & Bioengineering

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SummaryThe ability to simultaneously measure both biofilm thickness and the mass transfer coefficient of an inert tracer through it provides a powerful method to study biofilm development. In this communication previously published data has been collated to interpret global trends in biofilm structure during the transition towards steady-state. It appears that sudden changes in biofilm structure (directly related to the rate of change of biofilm mass transfer resistance) may occur following transitions in rate of biomass production. These observations are consistent with the concept of consolidation, recently introduced into spatially structured biofilm mathematical models to account for structural realignment of the biofilm under dynamic conditions.

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“…This is despite the fact that the P-lactamase of P. aeruginosa would not be considered to be very active against cefsulodin (Livermore, 1983 ;Hewinson, 1988). The idea that a continuously removed penetrating substance finally attains steady-state gradients of concentration and flux throughout a biofilm was also demonstrated by Matson & Characklis (1976) for nutrient diffusion occurring simultaneously with a zero-order reaction. We speculate that the above phenomenon contributes to the well-known 'inoculum effect' that is observed with P-lactamase-producing bacteria (e.g.…”

Section: Modelling Antibiotic Penetration Into Biojlms and Microcoloniesmentioning

confidence: 99%

“…where k is a first-order rate constant for the irreversible reaction, and the other symbols are as above (for solutions of the problem of diffusion occurring together with zero-order reaction, see Matson & Characklis, 1976). Both of the series solutions for C already presented (equations 1 and 2) were of the form c b / c O or cc/co = 1 -x f ( x ) exp( -vt) (equation 14.23 of Crank, 1975).…”

Section: W W Nichols a N D Othersmentioning

confidence: 99%

The Penetration of Antibiotics into Aggregates of Mucoid and Non-mucoid Pseudomonas aeruginosa

et al. 1989

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~~ ~ ~Cells of mucoid and non-mucoid Pseudomonas aeruginosa in colonies were at least onethousandfold less sensitive to the antibiotics tobramycin or cefsulodin than were cells of the same bacteria in dispersed suspension. We did not detect any difference between the mucoid form and the non-mucoid form in the antibiotic sensitivity of colonies, from which we infer that the exopolysaccharide of the mucoid form does not contribute to colony-resistance by forming a barrier to antibiotic diffusion. Mathematical models were constructed in order to estimate timecourses of penetration of tobramycin and cefsulodin into biofilms and microcolonies of mucoid and non-mucoid P. aeruginosa. For tobramycin penetration, adsorption of antibiotic to the exopolysaccharide of the glycocalyx and antibiotic uptake by cells were taken into account in the calculations. The longest time-period for the concentration of tobramycin at the base of a biofilm 100 prn deep to rise to 90% of the concentration outside the biofilm was predicted to be 2.4 h. For cefsulodin penetration, irreversible hydrolysis catalysed by p-lactamase was taken into account, using P-lactamase levels taken from the literature. The calculations predicted that the cefsulodin concentration at the base of a biofilm 100pm deep would rise to 90% of the external concentration in 29 s when the /I-lactamase was synthesized at the basal level. For a similar biofilm of bacteria synthesizing enhanced levels of fl-lactamase ('derepressed'), the concentration of cefsulodin at the base was calculated to rise to 41% of the external concentration in about 50s and then remain at that level. This was despite the fact that cefsulodin is a poor substrate for this P-lactamase.

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Diffusion into microbial aggregates

Cited by 123 publications

References 2 publications

Diffusional Properties of Methanogenic Granular Sludge: ¹ H NMR Characterization

Diffusional Properties of Methanogenic Granular Sludge: ¹ H NMR Characterization

Tracer measurements reveal experimental evidence of biofilm consolidation

The Penetration of Antibiotics into Aggregates of Mucoid and Non-mucoid Pseudomonas aeruginosa

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Diffusion into microbial aggregates

Cited by 123 publications

References 2 publications

Diffusional Properties of Methanogenic Granular Sludge: 1 H NMR Characterization

Diffusional Properties of Methanogenic Granular Sludge: 1 H NMR Characterization

Tracer measurements reveal experimental evidence of biofilm consolidation

The Penetration of Antibiotics into Aggregates of Mucoid and Non-mucoid Pseudomonas aeruginosa

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Diffusional Properties of Methanogenic Granular Sludge: ¹ H NMR Characterization

Diffusional Properties of Methanogenic Granular Sludge: ¹ H NMR Characterization