PREINCUBATION OF PENICILLIUM-COMMUNE-CONIDIA UNDER MODIFIED ATMOSPHERE CONDITIONS - INFLUENCE ON GROWTH-POTENTIAL AS DETERMINED BY AN IMPEDIMETRIC METHOD
I. Haasum et Pv. Nielsen, PREINCUBATION OF PENICILLIUM-COMMUNE-CONIDIA UNDER MODIFIED ATMOSPHERE CONDITIONS - INFLUENCE ON GROWTH-POTENTIAL AS DETERMINED BY AN IMPEDIMETRIC METHOD, Journal of Stored Products Research, 32(4), 1996, pp. 329-337
The combined effect of preincubation time, relative humidity (r.h.), h
eadspace carbon dioxide (CO2) and oxygen (O-2) on subsequent growth po
tential of conidia from Penicillium commune was studied using Response
Surface Modelling (RSM). Native conidia were preincubated under modif
ied atmosphere conditions in sealed vials for 14, 35 and 56 d. Lag tim
e and growth rates were determined using impedance microbiology on a B
actometer. Conidia survived and some swelling was observed during all
experimental preincubation. conditions. Regression analysis of the sub
sequent growth responses showed that relative humidity in the vials wa
s the most significant factor affecting lag time of the conidia after
preincubation for 14 and 35 d. Storage for 35 d extended lag times by
15 h when the level of r.h. was increased from 41% to 80%. After prolo
nged storage (56 d) r.h. and CO2 levels elicited a significant effect
on the growth potential of the conidia. Increasing CO2 levels (7% to 2
0%) in the storage atmosphere, reduced lag times from 65 to 25 h. By t
he same increase in CO2 levels, at 70% r.h., growth rates were doubled
. Oxygen in the range 2-18%, did not produce any significant effect on
either lag time or growth rate during the time of preincubation. This
paper describes the first investigation of the combined effect of two
significant environmental factors on the growth potential of conidia
from P. commune. It is demonstrated that storage for more than 56 d in
levels of CO2 below 20% results in sublethal injury of the conidia fr
om P. commune, retarding growth by increasing lag times and decelerati
ng growth rates. Copyright (C) 1996 Published by Elsevier Science Ltd