Cs. Young et al., SURVIVAL OF INOCULATED BACILLUS-CEREUS SPORES AND VEGETATIVE CELLS INNON-PLANTED AND RHIZOSPHERE SOIL, Soil biology & biochemistry, 27(8), 1995, pp. 1017-1026
The survival of vegetative cells and spores of an antibiotic-resistant
Bacillus cereus (B11) inoculant was similar in wheat rhizosphere soil
and non-planted soil over a period of 21 d. Reliable ways of producin
g either spore or vegetative single cell inocula were developed. When
applied to give densities ranging from 1 x 10(2) t o 1 x 10(7) g(-1) s
oil, B11 spores survived for at least 21 d at levels similar to those
introduced but numbers of vegetative cells decreased by 1-2 orders of
magnitude within the first 48 h and the extent of decrease was proport
ionately greater at low inoculum density. There was no significant dif
ference after 21 d between total counts (vegetative cells + spores) or
spore counts in either the rhizosphere or non-planted soil, regardles
s of whether the inoculant was composed of vegetative or spore cells.
There was no difference between the changing spore-to-vegetative cell
ratio within total cell counts between rhizosphere and non-planted soi
l. Inoculating soil with a mixture of Bacillus B11 (2 x 10(7) g(-1)),
Flavobacterium P25 (3 x 10(8) g(-1)) and Arthrobacter A109 (2 x 10(8)
g(-1)) increased the survival of P25 and A109 but decreased the surviv
al of B11 in both non-planted and rhizosphere soil compared with each
bacterium inoculated alone. For example, at day 21 in rhizosphere soil
there were 1 x 10(6) g (-1) A109 (single inoculant) and 1 x 10(7) g(-
1) A109 (mixed inoculum) and in non-planted soil 1 x 10(5) g(-1) (sing
le) and 1 x 10(7) g(-1) (mixed). Thus, neither the survival nor the ph
ysiological state of Bacillus B11 was affected by the presence of deve
loping wheat roots but survival was negatively affected by the presenc
e of other inoculants.