Fast coliform detection in portable microbe enrichment unit (PMEU) with Colilert® medium and bubbling  Elias Hakalehto, Anneli Heitto, Lauri Heitto  Pathophysiology  Volume 20, Issue 4, Pages 257-262 (September 2013) DOI: 10.1016/j.pathophys.2013.05.001 Copyright © 2013 Elsevier Ireland Ltd Terms and Conditions

Fig. 1 Klebsiella mobilis cultivation in PMEU Coliline™ using Colilert® as the growth medium without gas bubbling. The growth was initiated in 13–18h depending on the inocula. Pathophysiology 2013 20, 257-262DOI: (10.1016/j.pathophys.2013.05.001) Copyright © 2013 Elsevier Ireland Ltd Terms and Conditions

Fig. 2 Hospital strains of Escherichia coli cultivated in PMEU Coliline™. Bacterial growth started in 10h in Colilert® medium and without gas bubbling. Pathophysiology 2013 20, 257-262DOI: (10.1016/j.pathophys.2013.05.001) Copyright © 2013 Elsevier Ireland Ltd Terms and Conditions

Fig. 3 Escherichia coli ATCC8739 strain cultivated in PMEU Coliline™ in Colilert® medium without gas bubbling. Time lapsed before the onset of growth was dependent on the dilutions of the inoculum being 2h with the dilution 10E−3, 3.5h with the dilution 10E−4, 5h with the dilution 10E−5. With the dilution 10E−8 bacterial growth started after 15h. This dilution corresponded to the initial concentration of 1–10cfu/ml (results not shown here). The secondary sensors of the PMEU Coliline™ verified the presence of E. coli by detecting the emitted UV fluorescence. Pathophysiology 2013 20, 257-262DOI: (10.1016/j.pathophys.2013.05.001) Copyright © 2013 Elsevier Ireland Ltd Terms and Conditions

Fig. 4 (a) Escherichia coli growth starting after about 4h in the nitrogen flow in the first syringe of chained five syringes containing added vancomycin. The growth peaked approximately at time point 10h. (b) Escherichia coli growth starting almost directly after inoculation in the fifth PMEU syringe culture containing vancomycin, positioned into a gas flow from the preceding culture syringe in series chained by the gas flow. The growth peaked at approximately time point 5.5h for the first time, but the optical density continued to increase also after that for more than 12h, even though the exponential phase ceased already at 3.5h. This could be resulting from some secondary growth. The lack of proper lag phase in the last culture in the chain illustrates the potential of bubble gas flow in stimulating the growth, as the successive production of volatiles in the preceding syringes has caused the alterations in the growth mode in the fifth and last syring culture in the chain. Pathophysiology 2013 20, 257-262DOI: (10.1016/j.pathophys.2013.05.001) Copyright © 2013 Elsevier Ireland Ltd Terms and Conditions