Steady state growth space study of Lactococcus lactis in D-stat cultures

• Published in: Antonie van Leeuwenhoek 2009-11, Vol.96 (4), p.487-496
• Main Authors: Lahtvee, Petri-Jaan, Valgepea, Kaspar, Nahku, Ranno, Abner, Kristo, Adamberg, Kaarel, Vilu, Raivo
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial physiology; Bacteriology; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biomedical and Life Sciences; Biotechnology; Cell culture; Chemostats; Continuous culture; Cultivation techniques; Data processing; Environmental changes; Environmental conditions; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Growth conditions; Growth rate; Hydrogen-Ion Concentration; Hysteresis; Lactococcus lactis; Lactococcus lactis - growth & development; Life Sciences; Medical Microbiology; Metabolism; Microbiology; Microorganisms; Miscellaneous; Mission oriented research; Original Paper; pH effects; Physiology; Physiology and metabolism; Plant Sciences; Soil Science & Conservation; Standard deviation; Stress, Physiological; Temperature; Temperature effects
• ISSN: 0003-6072; 1572-9699
• DOI: 10.1007/s10482-009-9363-2

Growth space of Lactococcus lactis subsp. lactis IL1403 was studied at constant growth rate using D-stat cultivation technique. Starting from steady state conditions in a chemostat culture (μ = 0.2 h⁻¹), the pH and/or temperature were continuously changed in the range of 5.4-6.4 and 26-34°C, respectively, followed by the return to the initial environmental conditions. Based on substrate consumption and product formation yields and expression changes of 1,920 genes, it was shown that changes of physiological state were not dependent on the direction of movement (from pH 6.3 to 5.4 or from 5.4 to 6.3), showing that quasi steady state values in D-stat corresponded to the steady state values in chemostats. Relative standard deviation of growth characteristics in triplicate D-stat experiments was below 10%. Continuing the experiment and reestablishing initial growth conditions revealed in average 7% difference (hysteresis) in growth characteristics when comparing chemostat steady state cultures prior and after the change of environmental conditions. Similarly, shifts were also seen at gene expression levels. The large amount of quantitatively reliable data obtained in this study provided a new insight into dynamic properties of bacterial physiology, and can be used for describing the growth space of microorganisms by modeling cell metabolism.