Formation of Crystalline δ-Endotoxin or Poly-β-Hydroxybutyric Acid Granules by Asporogenous Mutants of Bacillus thuringiensis

Abstract

Parental strains and asporogenous mutants of Bacillus thuringiensis subspp. kurstaki and aizawai produced high yields of &-endotoxin on M medium, which contained 330 p.g of potassium per ml, but not on ST and ST-a media, each of which contained only 11 p.g of potassium per ml. On ST and ST-a media, refractile granules were formed instead. These granules had no insecticidal activity against silkworms and were isolated and identified as poly-p-hydroxybutyric acid. Supplementation of the potassium-deficient ST-a medium with 0.1% KH2PO4 (3.7 mM) led to the formation of crystalline 8-endotoxin. The replacement of KH2PO4 with equimolar amounts of KCl, KNO3, and potassium acetate or an equivalent amount of K2SO4 had a similar effect, whereas the addition of an equimolar amount of NaH2PO4 or NH4H2PO4 did not cause the endotoxin to form. An asporogenous mutant, B. thuringiensis subsp. kurstaki strain 290-1, produced 5endotoxin on ST-a medium supplemented with 3 mM or more potassium but formed only poly-3-hydroxybutyric acid granules on the media containing .1 mM potassium. These results clearly indicate that a certain concentration of potassium is essential for the fermentative production of 6-endotoxin by these isolates of B. thuringiensis. Manganese could not be substituted for potassium. Phosphate ions stimulated poly-,B-hydroxybutyric acid formation by strain 290-1. The sporulation of B. thuringiensis and several other Bacillus strains was suppressed on the potassium-deficient ST medium. This suggests that potassium plays an essential role not only in Bacillus cell growth and 5-endotoxin formation but also in sporulation.

Polyhydroxyalkanoate biosynthesis in Bacillus cereus SPV under varied limiting conditions and an insight into the biosynthetic genes involved

“…Potassium sulphate is the limiting factor leading to the PHA formation in Bacillus thurungiensis (Kim and Lenz 2001). In the present study, by limiting potassium, we obtained maximum cellular growth (1AE71 g l )1 ) and PHA accumulation (13AE4% dcw) at 48 h. Wakisaka et al 1982 reported that phosphate ion concentration higher than 120 lg ml -1 stimulated P(3HB) production in the Bacillus strain 290-1. However, in the present study by limiting phosphate, cell growth was found to be very low (0AE18 g l )1 ) although the P(3HB) yield was better (33AE33% dcw) compared to potassium (13AE4% dcw) or sulphur (13AE15% dcw) limitation.…”

“…A previously reported potassium-deficient production medium (Wakisaka et al 1982) was used for PHA production under potassium-deficient conditions. The pH of the medium was adjusted to 6AE8 before autoclaving.…”

“…When B. cereus SPV was grown in the potassium limiting media (Wakisaka et al 1982), good growth was observed until 48 h (1AE71 g dcw l -1 ); however, there was a sharp decrease in growth after 72 h of growth (0AE86 g dcw l -1 ) ( Table 1). The PHA yield increased up to 13AE4% dcw at 48 h after which it decreased.…”

“…kurstaki strain B-43-d-e and B. thuringiensis subsp. aizawai strain B-106-4-4 (Wakisaka et al 1982). Potassium sulphate is the limiting factor leading to the PHA formation in Bacillus thurungiensis (Kim and Lenz 2001).…”

The influence of nutritional and environmental conditions on the accumulation of poly-beta-hydroxybutyrate in Bacillus mycoides RLJ B-017

“…A number of Bacillus spp. have been reported to accumulate 9±44á5% dry cell weight (DCW) PHA (Nickerson et al 1981;Wakisaka et al 1982;Haywood et al 1989;Anderson et al 1990;Ramsay et al 1990;Kofronova et al 1994; . This paper describes the in¯uence of nutritional and environmental conditions on the growth of and PHB accumulation by a new strain of Bacillus mycoides RLJ B-017.…”