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Cell counting and carbon utilization velocities via microbial calorimetry
Author(s) -
Boe Irwin,
Lovrien Rex
Publication year - 1990
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260350102
Subject(s) - calorimetry , chemistry , spectrophotometry , calorimeter (particle physics) , turbidity , cell counting , chromatography , bacterial growth , carbon fibers , analytical chemistry (journal) , bacteria , biochemistry , materials science , biology , cell , thermodynamics , cell cycle , ecology , physics , genetics , detector , composite number , electrical engineering , composite material , engineering
Bacteria rapidly metabolize sugars and produce heat accordingly ( Escherichia coli , aerobic conditions, 25°C). Two kinds of heat output are gotten: (1) from excess cells and limiting carbon, 2 × 10 9 to 5 × 10 9 cells, 5‐50 nanomole glucose; (2) from limited cells and excess carbon, 0. 1 × 10 9 ‐1 × 10 9 bacteria and 200‐600 nmol glucose. The thermograms from heat conduction calorimetry under the first conditions measure velocities of sugar uptake and initial metabolic throughput in 1‐6‐min time spans before a growth cycle possibly can occur. Under the second conditions with limited cells, power output plateaus to a steady state proportional to cell biomass and number of cells. In order to evaluate the calorimetric means for measuring number of cells, six independent means including spectrophotometry (turbidity) were compared: microkjeldahl nitrogen, biuret protein, dry weight, microscopy direct counting in Petroff‐Hausser chambers, and viable colony counting. Using turbidity as a central standard, all methods including calorimetry under the second set of conditions agree within ±18% of one another. Spectrophotometry is the most rapid method but is seriously interfered with by pigments that absorb and foreign particles that also scatter. Calorimetry requires 10‐30 min but measures cell numbers in opaque samples impossible for optical means.