Microwave radiation in Escherichia coli and Bacillus subtilis cell suspensions resulted in a dramatic reduction of the viable counts as well as increases in the amounts of DNA and protein released from the cells according to the increase of the final temperature of the cell suspensions. However, no significant reduction of cell density was observed in either cell suspension. It is believed that this is due to the fact that most of the bacterial cells inactivated by microwave radiation remained unlysed. Scanning electron microscopy of the microwave-heated cells revealed severe damage on the surface of most E. coli cells, yet there was no significant change observed in the B. subtilis cells. Microwave-injured E. coli cells were easily lysed in the presence of sodium dodecyl sulfate (SDS), yet B. subtilis cells were resistant to SDS.

Plant growth-promoting endophytic fungi with gibberellin-producing ability were isolated from the roots of Carex kobomugi Ohwi, a common sand-dune plant, and bioassayed for plant growth-promotion. A new strain, Arthrinium phaeospermum KACC43901, promoted growth of waito-c rice and Atriplex gemelinii. Analysis of its culture filtrate showed the presence of bioactive GA(1) (0.5 ng/ml), GA(3) (8.8 ng/ml), GA(4) (4.7 ng/ml) and GA(7) (2.2 ng/ml) along with physiologically inactive GA(5) (0.4 ng/ml), GA(9) (0.6 ng/ml), GA(12) (0.4 ng/ml), GA(15) (0.4 ng/ml), GA(19) (0.9 ng/ml) and GA(24) (1.8 ng/ml). The fungal isolate was identified through sequence homology and phylogenetic analysis of 18S rDNA (internal transcribed region).

The growth of red pepper plug seedlings was promoted by Bacillus cereus MJ-1, B. macroides CJ-29, and B. pumilus CJ-69 isolated from the rhizosphere. Gibberellins (GAs), a well-known plant growth-promoting hormone, were detected in the culture broth of their rhizobacteria. Among the GAs, the contents of GA1, GA3, GA4, and GA7, physiologically active GAs, were comparatively higher than those of others, suggesting that the growth promoting effect was originated from the GAs. This isthe first report on the production of GA5, GA8, GA34, GA44, and GA53 by bacteria.

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