Sensitivity of partially purified ice nucleation activity of Fusarium acuminatum SRSF 616

Factors that affect bacterial ice nucleation, including growth medium, grow th phase, nutrient deprivation, and cold-temperature exposure, were investi gated in the ice nucleation active (INA) fungus Fusarium acuminatum SRSF 61 6. Ice nucleation activity remained relatively constant throughout the grow th cycle, and the cell-free culture supernatant consistently displayed high er ice nucleation activity than the hyphal pellet. Although nutrient starva tion and low-temperature exposure enhance bacterial ice nucleation activity , reducing the concentration of C, N, or P in synthetischer nahrstoffarmer broth (SNB) did not increase fungal ice nucleation activity, nor did exposu re to 4 degreesC or 15 degreesC. From the SNB supernatant, selected INA chr omatography fractions were obtained that demonstrated increased sensitivity to proteinase K and heat compared with culture supernatant. We propose tha t partial purification of the fungal ice nuclei resulted in removal of low- molecular-weight stabilizing factors.