The Egg-Yolk Reaction of Aerobic Sporing Bacilli

Abstract

SUMMARY: Among a large number of strains of aerobic sporing bacilli only Bacillus cereus, B. mycoides and, to a lesser extent, B. anthracis were able to produce turbidity and formation of a curd in saline extract of egg-yolk. None of the other species tested, namely, B. alvei, B. alcalophilus, B. brevis, B. carotarum, B. Circulans, B. coagulans, B. fusifomnis, B. licheniformis, B. macerans, B. megatherium, B. pumilus, B. polgmgxa, B. orpheecs, B. repens and B. subtilis caused any opalescence in the yolk medium. The yolk reaction was due to the action of phospholipinase produced by the organisms. As in the case of Cl. we&hii a-toxin, the yolk curd-forming activity of B. cereus and B. mycoides also was associated with haemolytic activity. The substances responsible for these activities appear to be sirhilar, and may be identical. The yolk reaction has proved useful for the rapid identification of B. cereus, as it is more specific than any of the other distinguishing tests hitherto employed. The three positive organisms, B. cereus, B. mycoides and B. anthracis, have been considered by previous workers on the grounds of morphology and antigenic structure to be closely related. Nagler (1989) described the effect of CZ. welchii cultures and toxic filtrates on human serum in producing an opalescence and curding (Nagler reaction) ; later Macfarlane, Oakley & Anderson (1941) found that egg-yolk saline (a lecithovitellin emulsion) is even more sensitive than human serum (the lecithovitellin (L.v.) reaction). Macfarlane & Knight (1941) then showed that the production of oialescence in egg-yolk emulsion was due to the action of a lecithinase, which split phosphocholine from lecithin, in the CZ. welchii toxic filtrates which was probably identical with the a-toxin. Since then, the Nagler reaction and the lecitho-vitellin (L.v.) reaction have been extensively used for the titration of a-toxin of CZ. welchii (Nagler, 1939; van Heyningen, 1941 a) and for the rapid identification of certain clostridia (Hayward, 1941(Hayward, , 1948.It is interesting that Nagler (1989) observed a non-pathogenic aerobic sporebearing bacillus which caused an opalescence in human serum like that caused by CZ. welchii; but the effect was not inhibited by CZ. welchii antitoxin. Crook (1942) and Hayward (1943) also mentioned that some aerobic bacteria caused similar opalescence. In the light of these observations we have sought for similar enzymes in the aerobic spore-bearing bacilli. The work started with a survey of the Bacillus group to ascertain which of them produced an eggyolk reaction. A test of 260 identified strains, comprising 24 species, showed that only B. cereus, B. mycoides and some strains of B. anthracis were positive.In comparison with other characteristics generally used for the differentiation of the BaeilZzcs group, the yolk reaction seems to be much more selective. One can hardly find any other characteristics which are confined to only two or three species of this very large group of organisms, and the test deserves the ...

Bacillus anthracisPhospholipases C Facilitate Macrophage-Associated Growth and Contribute to Virulence in a Murine Model of Inhalation Anthrax

“…The gamma-hemolysis is thought to be a consequence of the truncated transcriptional activator PlcR, resulting in the silencing of the PlcR regulon (20). However, low levels of hemolysis have been reported for various B. anthracis strains, in addition to lecithinase activity (13,19). Earlier reports imply that PLC expression may be induced under strictly anaerobic growth (15).…”

Phosphatidylcholine-Preferring Phospholipase C from B. cereus. Function, Structure, and Mechanism

“…The history of bacterial phospholipase C activity dates back to 1948 when bacterial strains from the Bacillus genus were screened for the hydrolysis of phosphatidylcholine on agar plates [20]. B. cereus gave a strong positive response, whereas B. anthracis and B. mycoides exhibited weaker activity.…”

Penicillin resistance in soil bacteria is an index of soil metal content near a porphyry copper deposit and near a concealed massive sulfide deposit

“…cereus colonies in overnight pour plates made by amending our medium with 2.5% (volume/volume) egg yolk as a 1:1 dilution in deionized water and 0.5% (weight/volume) trisodium citrate as recommended by Donovan (1958). According to McGaughey and Chu (1948), only two Bacil lus species give positive results with this test, Bacillus cereus and Bacillus anthracis. The anthrax bacillus, apart from being rare enough to be dismissed a priori at most sites, gives a much weaker reaction than B_.…”

“…cereus with egg yolk agar (the opaque zone not extending beyond the colony in the case of B. anthracis). McGaughey and Chu (1948) Data were standardized by the following procedure. All percent values were plotted on the y_ (4-cycle) axis against test concentrations of penicillin on the 21 (6-cycle) axis of 4x6 cycle log paper for each soil site.…”