Catabolic repression of bacterial sporulation.

Abstract

The formation of endospores in bacteria is generally studied in media which do not support growth: the exhausted growth medium or a solution of mineral salts into which washed growing bacteria are transferred.", 2 Under carefully adjusted cultural conditions, a reasonably synchronous sporulation can thus be obtained in the majority of the population. There seems therefore to be no need, and even no possibility, for a change in the conventional methods used to study sporulation.An entirely new approach became available in 1961, however, when it was observed that spores are constantly being formed in cultures of Bacillus rnegateriuin growing exponentially in a mineral-glucose medium.3 Similar results have recently been obtained with B. subtilis.' Relative to the total viable population, the number of spores first reaches a limit value, and then increases with time at a constant rate, equal to the growth rate of the total population.3The present work investigates the influence of various factors on the size of the sporulated fraction (hereafter called p) in growing cultures of B. subtilis. The interpretation of the results is that the probability for a cell in a growth medium to become committed to sporulate" I must be determined by the intracellular concentration of at least one nitrogen-containing catabolite repressing, directly or indirectly, the expression of all the sporulation genes. A preliminary account of this work has been included in recent reviews;6 further evidence supporting the proposed interpretation will be published elsewhere.8' I Experimental Procedure.-The wild Marburg strain of Bacillus subtilis has been used. A common mineral base for all media was prepared from the following three solutions (all figures in gm/liter); solution I: K2HP04, 10.5; KH2PO4, 3.5; solution II: MIgSO4, 7H20, 5.0; FeSO4, 7H20, 0.5; solution III: CaCl2, 5.0; MnCl2, 4H20, 0.5; solutions I and III were autoclaved, solution II sterile-filtered. The base medium is made of 100 vol of solution I for 1 vol each of solutions II and III. Various substances are then added as carbon or as nitrogen source; the complete medium is thus fully described with the mention of the nature of each source, followed, in gm/liter, by its concentration [e.g., NH4Cl(0.5)-glucose (2)].

A functional Spo0A is required for maximal aprE expression in Bacillus subtilis

“…subtilis cells carrying pSG35.1 and pSub-204 ( Fig. 1) were grown at 37°C in Schaeffer's sporulation media [11]. At regular time intervals, samples of 1 ml were taken and assayed for B-galactosidase specific activity as described in [9].…”

Selection of Bacillus species for targeted in situ release of prebiotic galacto-rhamnogalacturonan from potato pulp in piglets

“…The strains were isolated from mainly feces of humans, chickens and pigs or from soil (Supplementary Table S1). Strain 10894 that is identical to isolate 37 in (Barbosa et al 2005 (Schaeffer et al 1965). For evaluation of biofilm formation, the strains were grown in biofilm medium (LB medium supplemented with 0.1 mM MnCl 2 , and 3 % v/v glycerol) (Trejo et al 2013).…”

“…Prior to harvest the degree of sporulation was evaluated by microscopy, and the concentration was estimated by plating serial dilutions on LB agar plates and counting colony forming units (Schaeffer et al 1965).…”

“…It is consequently of importance for the industrial application that the strains can efficiently sporulate. In this study, spores were prepared using a standard procedure for B. subtilis (Schaeffer et al 1965). Using this method, spore concentration was in the order 10 8 spores/mL.…”

Development of natto with germination-defective mutants of Bacillus subtilis (natto)

“…NAFM5 was a derivative of the major natto starter, Miyagino strain, and NAFM5 had the competence ability. B. subtilis was grown on LB medium (Sambrook et al 1989) at 37°C overnight, inoculated into DSM (Schaeffer sporulation medium) (Schaeffer et al 1965), and then shaken at 37°C. If necessary, kanamycin and tetracycline were added to the medium to final concentrations of 20 and 10 µg ml -1 , respectively.…”