Membrane inlet mass spectrometric measurement of O2 and CO2 gradients in cultures of Lactobacillus paracasei and a developing Cheddar cheese ecosystem

Tammam, Jonathan; Williams, Alan G.; Banks, J. M.; Cowie, G. A.; Lloyd, David

doi:10.1016/s0168-1605(00)00438-4

Cited by 18 publications

(11 citation statements)

References 25 publications

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“…The aerobic zone is considered to exist through 30–40 μm depth in a gelatine medium (Walker et al, 1997 ). However, Tammam et al ( 2001 ), questions the use of micro-electrodes because they can give non-reproducible results due to the poisoning of the platinum electrodes by other ions. Instead, these authors developed in situ mass spectroscopy measurements to investigate the concentrations of O 2 and CO 2 concentrations in MRS agar inoculated with a strain of L. paracasei (Tammam et al, 2001 ).…”

Section: Growth In Colonies: When and How It Differs From Planktonic mentioning

confidence: 99%

“…However, Tammam et al ( 2001 ), questions the use of micro-electrodes because they can give non-reproducible results due to the poisoning of the platinum electrodes by other ions. Instead, these authors developed in situ mass spectroscopy measurements to investigate the concentrations of O 2 and CO 2 concentrations in MRS agar inoculated with a strain of L. paracasei (Tammam et al, 2001 ). Their results show that O 2 was rapidly consumed by LAB metabolism, while CO 2 was produced as expected.…”

Section: Growth In Colonies: When and How It Differs From Planktonic mentioning

confidence: 99%

“…A MIMS (membrane inlet mass spectrometric) probe was inserted through column of growth. Adapted from Tammam et al ( 2001 ).…”

Section: Growth In Colonies: When and How It Differs From Planktonic mentioning

confidence: 99%

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Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions with the Micro-Environment

et al. 2015

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Bacteria, either indigenous or added, are immobilized in solid foods where they grow as colonies. Since the 80's, relatively few research groups have explored the implications of bacteria growing as colonies and mostly focused on pathogens in large colonies on agar/gelatine media. It is only recently that high resolution imaging techniques and biophysical characterization techniques increased the understanding of the growth of bacterial colonies, for different sizes of colonies, at the microscopic level and even down to the molecular level. This review covers the studies on bacterial colony growth in agar or gelatine media mimicking the food environment and in model cheese. The following conclusions have been brought to light. Firstly, under unfavorable conditions, mimicking food conditions, the immobilization of bacteria always constrains their growth in comparison with planktonic growth and increases the sensibility of bacteria to environmental stresses. Secondly, the spatial distribution describes both the distance between colonies and the size of the colonies as a function of the initial level of population. By studying the literature, we concluded that there systematically exists a threshold that distinguishes micro-colonies (radius < 100–200 μm) from macro-colonies (radius >200 μm). Micro-colonies growth resembles planktonic growth and no pH microgradients could be observed. Macro-colonies growth is slower than planktonic growth and pH microgradients could be observed in and around them due to diffusion limitations which occur around, but also inside the macro-colonies. Diffusion limitations of milk proteins have been demonstrated in a model cheese around and in the bacterial colonies. In conclusion, the impact of immobilization is predominant for macro-colonies in comparison with micro-colonies. However, the interaction between the colonies and the food matrix itself remains to be further investigated at the microscopic scale.

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Section: Growth In Colonies: When and How It Differs From Planktonic mentioning

confidence: 99%

Section: Growth In Colonies: When and How It Differs From Planktonic mentioning

confidence: 99%

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Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions with the Micro-Environment

et al. 2015

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“…Colonies of Bacillus cereus were cultured on the surface of tryptone soya broth agar (TSBA) contained in petri dishes and oxygen measurements were performed with an oxygen-sensitive microelectrode mounted on a prior micromanipulator. On the other hand, it has been reported the potential inaccuracy in the use of microelectrodes, due to oxygen leakage around the electrode and poisoning tip ( Tammam et al, 2001 ). Microelectrodes have also been applied for measuring pH gradients, e.g., Walker et al (1997) described the pH gradients within and around surface colonies of S. Typhimurium grown in an adapted gelatin cassette system.…”

Section: Studying Bacterial Colonies In Solid Model Food Systemsmentioning

confidence: 99%

Recent trends in non-invasive in situ techniques to monitor bacterial colonies in solid (model) food

Lobete¹,

Fernández²,

Impe³

2015

Front. Microbiol.

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Planktonic cells typically found in liquid systems, are routinely used for building predictive models or assessing the efficacy of food preserving technologies. However, freely suspended cells often show different susceptibility to environmental hurdles than colony cells in solid matrices. Limited oxygen, water and nutrient availability, metabolite accumulation and physical constraints due to cell immobilization in the matrix, are main factors affecting cell growth. Moreover, intra- and inter-colony interactions, as a consequence of the initial microbial load in solid systems, may affect microbial physiology. Predictive food microbiology approaches are moving toward a more realistic resemblance to food products, performing studies in structured solid systems instead of liquids. Since structured systems promote microbial cells to become immobilized and grow as colonies, it is essential to study the colony behavior, not only for food safety assurance systems, but also for understanding cell physiology and optimizing food production processes in solid matrices. Traditionally, microbial dynamics in solid systems have been assessed with a macroscopic approach by applying invasive analytical techniques; for instance, viable plate counting, which yield information about overall population. In the last years, this approach is being substituted by more mechanistically inspired ones at mesoscopic (colony) and microscopic (cell) levels. Therefore, non-invasive and in situ monitoring is mandatory for a deeper insight into bacterial colony dynamics. Several methodologies that enable high-throughput data collection have been developed, such as microscopy-based techniques coupled with image analysis and OD-based measurements in microplate readers. This research paper provides an overview of non-invasive in situ techniques to monitor bacterial colonies in solid (model) food and emphasizes their advantages and inconveniences in terms of accuracy, performance and output information.

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“…Although not designed for CP‐MIMS, the pioneering work of the Lloyd group developing miniature probes for ' in situ ' gaseous acceptor phase MIMS helped to inspire the CP‐MIMS probe design presented in this work. Additional influences were the miniature sampling probe designs utilized for in vivo micro‐dialysis .…”

mentioning

confidence: 99%

A miniature condensed‐phase membrane introduction mass spectrometry (CP‐MIMS) probe for direct and on‐line measurements of pharmaceuticals and contaminants in small, complex samples

Duncan

Willis

Krogh

et al. 2013

Rapid Comm Mass Spectrometry

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Membrane inlet mass spectrometric measurement of O2 and CO2 gradients in cultures of Lactobacillus paracasei and a developing Cheddar cheese ecosystem

Cited by 18 publications

References 25 publications

Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions with the Micro-Environment

Bacterial Colonies in Solid Media and Foods: A Review on Their Growth and Interactions with the Micro-Environment

Recent trends in non-invasive in situ techniques to monitor bacterial colonies in solid (model) food

A miniature condensed‐phase membrane introduction mass spectrometry (CP‐MIMS) probe for direct and on‐line measurements of pharmaceuticals and contaminants in small, complex samples

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