Freeze-drying of sol–gel encapsulated recombinant bioluminescent E. coli by using lyo-protectants

Tessema, Dejene A.; Rosen, Rachel; Pedazur, Rami; Belkin, Shimshon; Gun, Jenny; Ekeltchik, Irina; Lev, Ovadia

doi:10.1016/j.snb.2005.07.030

Cited by 20 publications

(13 citation statements)

References 30 publications

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“…Solution number 1, computed by the software having maximum desirability, was selected. At optimal conditions, 93.6423% R M C and 3.60763% R A E were predicted, corresponding to a drying time of only 4 h, which was much less than the 40 h reported by Tessema et al [28] The R M C value represents 4.8% final moisture content and R A E signifies acceptable a-amylase activity of the freeze-dried Bacillus subtilis MTCC 2396.…”

Section: Optimal Process Conditionsmentioning

confidence: 65%

Intensification of Freeze-Drying Rate ofBacillus subtilisMTCC 2396 Using Tungsten Halogen Radiation: Optimization of Moisture Content and α-Amylase Activity

2014

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A novel freeze-drying protocol has been explored to render fast and cost-effective freeze drying of hyperamylase producing Bacillus subtilis MTCC2396 employing a tungsten halogen lamp radiator (THLR) as a heat source. Response surface methodology assessed the maximum reduction in moisture content (96.07%) and minimum reduction in a-amylase (EC 3.2.1.1) activity (1.02%) in 4 h drying time at 42.5 C radiation temperature. a-amylase activity (0.046 U) and final moisture content (3.93%) of the optimally freeze-dried bacterial strain appeared satisfactory. The freeze-drying time using THLR (4 h) is remarkably lower compared to that under a conventional conductive plate heater (CPH) (10 h) at otherwise identical conditions. The higher effective moisture diffusivity of 0.0052 to 0.0078 m 2 /s under THLR compared to 0.00084 to 0.0015 m 2 /s under CPH (corresponding to 20-50 C) advocated the superiority of the THLR heating protocol. The higher efficacy of THLR was also evidenced through lower activation energy (8.42 kJ/mol) of moisture diffusion compared to that (12.051 kJ/mol) of CPH. The optimally freeze-dried bacteria demonstrated the same growth rate in addition to exhibiting excellent retention of bioremedial (Hg 2þ removal) activity to that of the control.

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Section: Optimal Process Conditionsmentioning

confidence: 65%

Intensification of Freeze-Drying Rate ofBacillus subtilisMTCC 2396 Using Tungsten Halogen Radiation: Optimization of Moisture Content and α-Amylase Activity

2014

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“…Changes in light emission or the production of fluorescent compounds by microorganisms might also be used as signals of unspecified stress (Kuncová et al 2004;Tessema et al 2006). However, other factors affecting BLM such as growth-phase (Heitzer et al 1992) or membrane perturbations (Heitzer et al 1998;Trögl et al 2007Trögl et al , 2010) have yet to be taken into account.…”

Section: Blmmentioning

confidence: 99%

Bioluminescence of Pseudomonas fluorescens HK44 in the course of encapsulation into silica gel. Effect of methanol

2010

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The bioluminescence (BLM) and colony-forming units (CFU) of Pseudomonas fluorescens HK44 were monitored during encapsulation into pre-polymerized Si(OMe)₄. The non-induced BLM of free cells was increased in the presence of 0.5-2.5 % MeOH. After mixing silica sol with the cell suspension, both BLM and CFU dropped to 1-3 and 8-18 %, respectively; both remained lowered as long as the silica biofilm contained residual MeOH. The kinetics of MeOH being released from silica biofilms (a thickness of 2-6 mm) were first-order. The decrease of bacterial activity due to encapsulation was proportional to the biofilm thickness. MeOH evolving during encapsulation is probably the principal stress factor but not the only one.

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“…Therefore, it is a good common practice to first process the semiconductor platform, second to deposit the cells and third, start the measurement. Most WCBC use prokaryotes with specific storage and handling procedures [19,20]. It can be extended to eukaryotes, such as yeast or even mammalian cells.…”

Section: Whole-cell Bio Sensors For Long Term Usagementioning

confidence: 99%

“…2. Cell storage methods [19,20], it depends on the cell type, longevity of use and the logistics involved in the specific application.…”

Section: Introductionmentioning

confidence: 99%

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Optical and Electrical Interfacing Technologies for Living Cell Bio-Chips

Shacham‐Diamand¹,

Belkin²,

Rishpon³

et al. 2010

CPB

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Whole-cell bio-chips for functional sensing integrate living cells on miniaturized platforms made by micro-system-technologies (MST). The cells are integrated, deposited or immersed in a media which is in contact with the chip. The cells behavior is monitored via electrical, electrochemical or optical methods. In this paper we describe such whole-cell biochips where the signal is generated due to the genetic response of the cells. The solid-state platform hosts the biological component, i.e. the living cells, and integrates all the required micro-system technologies, i.e. the micro-electronics, micro-electro optics, micro-electro or magneto mechanics and micro-fluidics. The genetic response of the cells expresses proteins that generate: a. light by photo-luminescence or bioluminescence, b. electrochemical signal by interaction with a substrate, or c. change in the cell impedance. The cell response is detected by a front end unit that converts it to current or voltage amplifies and filters it. The resultant signal is analyzed and stored for further processing. In this paper we describe three examples of whole-cell bio chips, photo-luminescent, bioluminescent and electrochemical, which are based on the genetic response of genetically modified E. coli microbes integrated on a micro-fluidics MEMS platform. We describe the chip outline as well as the basic modeling scheme of such sensors. We discuss the highlights and problems of such system, from the point of view of micro-system-technology.

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Freeze-drying of sol–gel encapsulated recombinant bioluminescent E. coli by using lyo-protectants

Cited by 20 publications

References 30 publications

Intensification of Freeze-Drying Rate ofBacillus subtilisMTCC 2396 Using Tungsten Halogen Radiation: Optimization of Moisture Content and α-Amylase Activity

Intensification of Freeze-Drying Rate ofBacillus subtilisMTCC 2396 Using Tungsten Halogen Radiation: Optimization of Moisture Content and α-Amylase Activity

Bioluminescence of Pseudomonas fluorescens HK44 in the course of encapsulation into silica gel. Effect of methanol

Optical and Electrical Interfacing Technologies for Living Cell Bio-Chips

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