Survival of Nocardia corallina and Degradation of Constituents during Starvation

Abstract

The survival of Nocardia corallina and the degradation of constituents were examined during periods of starvation. Organisms were harvested at the end of the growth phase and were starved, after resuspending in phosphate buffer containing Mg2+, with vigorous aeration at 30 "C. Viability fell gradually to 50 % over a period of 480 h. After 48 h of starvation the dry weight of the organisms was reduced by 35 % and the Qo, was decreased from I o to approximately I. The fall in dry weight coincided with a decrease of microbial polysaccharide from 25 % to 7 % of the initial dry weight. After this degradation of polysaccharide there was a decrease in microbial protein and a release of ammonia into the supernatant. The contribution of different constituents to the total decrease in dry weight during a period of 240 h starvation was; polysaccharide, 40 %; protein, 25 %; RNA, 6 %; total fatty acids, 5 %. Loss of viability could not be directly correlated with the utilization of any particular constituent.

The Survival of Coryneform Bacteria during Periods of Prolonged Nutrient Starvation

“…crystallopoietes (Boylen & Ensign, 19706) and N . corallina (Robertson & Batt, 1973). In view of the similarities in the retention of viability shown by these organisms, the differences observed in the rates of degradation of various macromolecules are probably not significant.…”

“…However, many organisms possessing such reserves are not truly starvation-resistant for long periods of time when compared with the coryneform bacteria (Boylen & Ensign, 1970a;Luscombe & Gray, 1974;Robertson & Batt, 1973 ;Zevenhuizen, 1966). Nevertheless, the coryneform organisms have been shown to degrade cellular constituents in much the same manner as other organisms.…”

A linear megaplasmid, p1CP, carrying the genes for chlorocatechol catabolism of Rhodococcus opacus 1CP

“…Members of the genus Rhodococcus are metabolically extraordinarily versatile (Finnerty, 1992;Warhurst & Fewson, 1994); exhibit slow growth rates but stable cell numbers (Golovlev, 1995), high tolerance to dryness and starvation (Koronelli et al, 1988;Robertson & Batt, 1973), weak catabolic repression by glucose (Warhurst & Fewson, 1994), and long-lasting induction levels in the absence of substrate (Cain, 1981;Dugan & Golovlev, 1983). Another characteristic that enables rhodococci to act as dominant degraders is their extraordinary ability to adapt.…”

Physiologie des bactéries du genre Lactococcus en conditions de privation nutritionnelle. Une revue

“…Dans ce contexte, la viabilité des bactéries étudiées en laboratoire n'est pas forcément étroitement corrélée avec les limites de survie dans l'environnement naturel. Toutefois, quand plusieurs souches de Laetoeoeeus sont étudiées conjointement, leur capacité à survivre est très proche, mais toutefois beaucoup plus courte que celle d'autres espèces bacté-riennes telles Arthrobaeter s p qui conserve 50% de viabilité après 1680 h de privation nutritionnelle (Ensign, 1970).Chez Noeardia corallina, le taux de consommation d'oxygène, la dégradation des glucides et le rejet d'ammoniaque dans le milieu extérieur sont approximativement 5 fois plus lents (Robertson et Batt, 1973) que chez E coli (Dawes et Ribbons, 1965), tandis que la capacité à survivre de N eorallina est également largement supérieure (480 h contre 36 h).La diminution de la viabilité est notamment corrélée au taux de dégradation des macromolécules pour chaque organisme au cours de la privation nutritionnelle. …”