Respiratory activity, molar growth yields, and ATP content in an Arthrobacter sp. ammonium-limited chemostat culture

Abstract

Respiratory activity, molar growth yields, and ATP content in. an Arthrobacter sp. ammonium-limited chemostat culture. Can. J. Microbiol. 29: 11 36-1140.ArthrobacterfIuorescens was grown in chemostat culture under ammonium-limited conditions and respiratory activity; molar growth yields and ATP content were determined over a wide range of dilution rates. Within a range of dilution rates between 0.10 h-' and 0.20 h-', morphological transition occurred, the ratio of cocci to rods appearing inversely related to growth rate. Molar growth yields for both glucose and ammonium decreased with increasing dilution rates because of the higher intracellular polysaccharide content at the lower growth rates. Different metabolic activities were shown in cocci, in rods, and during morphogenesis. A sharp decrease in in situ and potential oxygen quotient (Q(02)) and in ATP content was observed in the range of dilution rates in which morphological changes occurred.CACCIARI, I., D. LIPPI, S. IPPOLITI et W. PIETROSANTI. 1983. Respiratory activity, molar growth yields, and ATP content in an Arthrobacter sp. ammonium-limited chemostat culture. Can. J. Microbiol. 29: 1136-1 140. ArthrobacterfIuorescens a Ctt mis en cultures continues (chemostat) sous des conditions limittes d'ammonium et d'activitC respiratoire en vue de dCterminer dans une g a m e de taux de dilution les rendements molaires de croissance et la teneur en ATP. A I'intCrieur de cette gamme, entre 0,10 h-' et 0,20 h-', des transitions morphologiques sont survenues et le rapport des formes sphkriques aux formes en bkonnet s'est avCrC inversement relit5 au taux de croissance. Les rendements molaires de croissance, tant pour le glucose que pour l'ammonium, ont dtcru face a une augmentation des taux de dilution en raison de la teneur ClevCe des poly saccharides intracellulaires aux taux infkrieurs de croissance. DiffCrentes activitCs mCtaboliques se sont manifestCes chez les formes sphCriques, chez les bltonnets, et au cours de la morphogenkse. Un dtclin rapide a Ct C observt in situ du quotient oxygkne (Q(02)) potentiel et de la teneur en ATP dans les divers taw de ddution o~ des changements morphologiques sont survenus.[Traduit par le journal]

Effect of previous growth conditions on starvation survival and endogenous metabolism rate of Arthrobacter fluorescens

“…2). These results confirmed previous findings (CACCIARI et al 1985) and indicated that the organism grew less efficiently under oxygen limitation. The sudden stressful change in oxygen availability influenced significantly the starvation survival of cells from both growth rates (Table 1).…”

“…The loss of viability during starvation was an exponential process and its specific rate was reported as death rate that was calculated according to CHAMBERLIN and MITCHELL (1978). The rates of death (Table 1) were higher within the range of dilution rates in which morphological and physiological changes have been previously observed in the culture grown under the same nutritional conditions (CACCIARI et al 1983). …”

“…Protein content was measured by the method Of LOWRY et al (195 1) with bovine serum albumin as standard. The endogenous respiration rate of starved cultures was polarographically measured at 30 "C on 9 ml cells by means of a BECKMAN Model 0260 Oxygen Analyzer and the oxygen consumption was continuously recorded for about 30 min (CACCIARI et al 1985). Viable cell number was determined on the basis of colony forming units (c.f.u.)…”

“…The 0,-limited cultures were grown at D = 0.03 and 0.20 h-'. When the culture grown under ammonium limitation reached the steady state it was made oxygen-limited: the inlet air was replaced with a mixture of 97% (v/v) nitrogen and 3% (v/v) air, at the flow rate of 0.5 Vmin, and the (NH,),SO, concentration in the inflowing medium was increased from0.2 to 1 g/1 (CACCIARI et al 1985), to attain a new 0,-limited steady state. The gas mixture was achieved by means of a gas mixing pump as described by CACCIARI et al (1 979).…”

ATP level of a starving surface-bound and free-living marineVibriosp.

“…26,27]. It is noteworthy that a drop in ATP levels of Arthrobacter fluorescens was observed in the range of nutrients in which a decrease in respiratory activity was monitored [28]. Gustafsson [29] also reported a marked correlation between the ATP content and the specific heat production for Debaryomyces hansenii.…”