Table 6.

Growth of Vegetative Cells of Pseudomonas fluorescens ATCC 13525 and Serratia liquefaciens ATCC 27592 for 28 d at 7 mbar, 0°C, and CO₂-Enriched Anoxic Atmospheres

		Growthy
Bacteriax	Pressure (mbar)	7 days	14 days	21 days	28 days	30°C in O2/N2z
TSA
Pseudomonas fluorescens	1013	0 c	0 c	0.10 b	0.13 b	1.9 a
	7	0	0	0	0	2.1
Serratia liquefaciens	1013	0 d	0.10 c	0.20 bc	0.20 b	2.5 a
	7	0 d	0.17 c	0.26 c	0.37 b	2.6 a
TSAGN
Pseudomonas fluorescens	1013	0 c	0 c	0.10 b	0.15 b	1.9 a
	7	0	0	0	0	2.1
Serratia liquefaciens	1013	0 d	0.10 c	0.20 bc	0.23 b	2.4 a
	7	0 d	0.20 c	0.20 c	0.37 b	2.6 a

^xBacteria were grown for 28 d on trypticase soy agar (TSA) or TSA supplemented with 0.25% glucose and 0.1% potassium nitrate (TSAGN) at 7 mbar, 0°C, and CO₂-enriched anoxic atmospheres. Bacteria were rated on 7, 14, 21, and 28 d.

^yBacterial growth was rated using a 5×pair of jeweler's magnifying glasses. Growth was rated in only the 2^nd or 3^rd quadrants of three-quadrant streaked plates; the 1^st quadrant was ignored in order to avoid false positives. Rating scale: 4=large robust colonies>5 mm in diameter; 3=colonies 2–4 mm in diameter; 2=colonies ∼1 mm in diameter; 1=colonies ∼0.5 mm in diameter; 0.50=colonies<0.5 mm in diameter; 0.1=smallest visually discernible colonies (pin-prick-sized colonies at ∼0.1 mm in diameter); 0=no growth. All bacteria were grown on double-thick trypticase soy agar (TSA; 35 mL per plate). Data were 0.25-power transformed prior to analysis to induce homogeneity of variances. Letters in rows designate significant differences among time steps for individual species based on ANOVA and protected least-squares mean separation tests (P≤0.05; n=3).

^zAt the end of the assays, all cultures were transferred to lab conditions for an additional 48 h of incubation at 30°C, 1013 mbar, and O₂/N₂ atmosphere. In general, bacteria grew normally under lab conditions and were not killed by exposure to hypobaric, low-temperature, or anoxic atmospheres.