Determination of biomass

• US 4,965,206 A
• Filed: 02/09/1990
• Issued: 10/23/1990
• Est. Priority Date: 09/22/1986
• Status: Expired due to Term

• Current Assignee: Douglas B. Kell
• Original Assignee: Douglas B. Kell
• Inventors: Kell, Douglas B.
• Primary Examiner(s): Kamen, Noah P.
• Application Number:
  US07/479,211
• Time in Patent Office: 256 Days
• Field of Search: 436/149, 436/150, 435/3, 435/34, 435/39, 435/4, 435/29, 435/173, 435/289, 435/291, 435/313, 435/286, 324/61 R
• US Class Current: 435/287.1
• CPC Class Codes: G01N 33/48735 Investigating suspensions of cells, e.g. measuring microbe concentration by chemical means C12Q1/04; colony counters C12M1/34; concentration of particle suspensions in general G01N15/06

Abstract

Method and apparatus for the determination of biomass in a suspension, such as a culture, in `real` time and a fermentation process using the method. In the method the electrical capacitance of the suspension is measured and from the measurement the volume fraction of the suspension enclosed by the cytoplasmic membranes of the cells (biovolume) is determined.

Claims

1. A method for the determination of biomass in a medium comprising a suspending fluid and cells, electrodes being mutually spaced in said medium, the method comprising the steps of:

(a) generating a signal dependent on the dielectric permittivity of the material in the bulk of said medium, but essentially independent of the conductivity of the medium, using electrical capacitance measurement, and

(b) determining the volume fraction of the medium enclosed by the cytoplasmic membranes of the cells from said permittivity dependent signal.

2. A fermentation process utilizing a culture comprising a suspending fluid and cells, said process comprising the steps of:

(a) generating a signal dependent on the dielectric permittivity of the culture in the bulk of the culture using electrical capacitance measurement, at a suitable frequency, between electrodes mutually spaced in said culture or a sample thereof;

(b) providing an indication if the permittivity dependent signal differs from a predetermined value or falls outside a predetermined range, and/or

(c) altering the value of a process parameter to return said signal towards the predetermined value or range, said predetermined frequency being such that the dielectric permittivity of the material in the bulk of the culture between the electrodes depends on the volume fraction of the culture enclosed by the cytoplasmic membranes of the cells.

3. Apparatus for performing a fermentation utilizing a culture comprising a suspending liquid and cells, the apparatus comprising:

(a) a fermenter for containing the culture;

(b) electrodes mutually spaced in the fermenter so as to be in contact with the culture in use; and

(c) means for generating a signal dependent on the dielectric permittivity in the bulk of the culture, using electrical capacitance measurement between the electrodes, at a predetermined frequency.

4. An apparatus as in claim 3 further comprising means for determining whether the permittivity dependent signal differs from a predetermined value or falls outside a predetermined range.

5. An apparatus as in claim 4 further comprising means for altering one or more parameters of the process to return the permittivity dependent signal towards the predetermined value or the predetermined range, responsive to said means for determining.

6. An apparatus as in claims 3, 4 or 5, wherein said predetermined frequency is in the range 0.1 MHz to 10 MHz.