Electronically controlled continuous culture device

New Type of Turbidostat with Intermittent Determination of Cell Density Outside the Culture Vessel

An inexpensive turbidostat featuring intermittent determination of optical density in an interchangeable measuring tube and incorporating electronic circuits for the automated mechanics is described.

Influence of temperature on substrate and energy conversion in Pseudomonas fluorescens

The influence of temperature on yield, maintenance rate, growth rate, and conversion of calories to biomass was studied with Pseudomonas fluorescens grown in a chemostat. Maintenance and growth rate are influenced linearly with temperature. Both rates increased with increasing temperature and gave linear Arrhenius plots over a limited range. Cells harvested during the steady-state at each temperature were burned in a microcalorimeter. The number of kilocalories per gram (dry weight) of organism was not influenced significantly by the temperature during growth, indicating that the conversion of substrate calories into biomass is apparently regulated in the range of temperature studied.

Use of a fiber optic probe for spectral measurements and the continuous recording of the turbidity of growing microbial cultures

This paper describes the properties and use of a fiber optic probe as an attachment to a spectrophotometer and its use for measurements in solutions and turbid suspensions. Measurements of a standard were identical when a spectrophotometer equipped with the probe was used or when a spectrophotometer was used in a conventional manner. The probe was calibrated for turbidimetric measurements with microorganisms by relating the apparent absorbancy measured on the spectrophotometer to the dry weight of each species of organism. Continuous measurements were made of the turbidity of growing cultures of Escherichia coli, Streptococcus mutans, and Saccharomyces cerevisiae. Transient changes in cell mass were observed in some cultures during continuous monitoring of growth. The data were recovered in a manner which allowed direct computer processing.

Automated continuous culture of mammalian cells in suspension

A system has been developed for the continuous culture of mammalian cells in suspension. The system maintains constant cell concentrations (monitored as the degree of light scattering) over a wide range of previously selected values by automatic additions of known amounts of medium and simultaneous withdrawals of equal volumes of cell suspension.

Automatic sample collector for continuous cultures

An automatic sample collector is described that samples growing cultures sequentially. It can be programmed to collect at preselected intervals (usually several hours apart) for a prescribed period (usually from minutes to hours). Samples are collected serially but during intermediate time periods; when the sample is not required, it is disposed of by diverting it into a discard reservoir. This device collects culture samples on a predetermined schedule and stores them under refrigeration for study at a later time.