TABLE 2.

Sporulation efficiency after 3 days of incubation at 30°Ca

Growth conditionsParameter (unit)Result for strain and medium
PY79 HU58 HU78
DSMDSM + NO2DSM + NO3DSMDSM + NO2DSM + NO3DSMDSM + NO2DSM + NO3
AerobicTotal count (CFU/plate)2.1 × 1010 2.21 × 1010 1.05 × 1010 2.07 × 1010 2.18 × 1010 1.88 × 1010 1.46 × 1010 1.19 × 1010 1.31 × 1010
Spore count (CFU/plate)1.82 × 1010 2.22 × 1010 1.04 × 1010 1.96 × 1010 2.02 × 1010 1.82 × 1010 1.40 × 1010 1.16 × 1010 1.30 × 1010
Sporulation efficiency (%)87100999593979899100
AnaerobicTotal count (CFU/plate)1.97 × 107 2.85 × 107 2.48 × 107 0.92 × 107 1.96 × 107 1.48 × 107 1.54 × 107 2.45 × 107 2.11 × 107
Spore count (CFU/plate)923274.14 × 104 2.44 × 106 2.36 × 106 9.1 × 105 6.6 × 106 1.19 × 107
Sporulation efficiency (%)4.6 × 10−5 8.1 × 10−5 1.1 × 10−4 0.5121662756
  • a B. subtilis strains grown in liquid culture were plated on solid DSM agar plates. For anaerobic growth, potassium nitrate or potassium nitrite was added to the medium as an electron acceptor. After 72 h of incubation at 30°C, the entire bacterial lawn was recovered from each plate, and the suspension was serially diluted and plated out for CFU or heat treated (68°C, 45 min) before serial dilution to determine spore counts.