Bacteria within ovules and seeds

Surface-sterilized ovules and seeds of 27 species of plants were cultured in the water of syneresis of a nutrient medium low in agar content. Bacteria were obtained from 30% of the ovules, 15% of the seeds of herbaceous plants, 16% of the seeds of woody plants, 5.4% of the overwintered noncereal seeds, and 13.5% of overwintered cereal seeds. In no instance did every ovule or seed of a plant species contain bacteria. No bacteria were obtained from the hard, waxy seeds of mimosa or yellowwood. They were not obtained from ovules with unbroken coats or from seeds with coats that were not ruptured during the swelling of the seed. Only one species of bacteria was recovered in 93% of the instances in which bacteria were obtained. Bacteria were obtained from seeds that were embedded in the acidic parenchyma of the lemon or surrounded by the thickened flesh of the cucurbits. The bacteria were distributed among 19 genera and 46 species. The species isolated in greatest numbers were Bacillus megaterium, B. cereus, Erwinia herbicola, Flavobacterium devorans, and Pseudomonas fluorescens. Bacteria recovered less frequently were in the genera Achromobacter, Acinetobacter, Alcaligenes, Brevibacterium, Corynebacterium, Cytophaga, Leuconostoc, Micrococcus, Nocardia, Proteus, Streptococcus, Streptomyces, and Xanthomonas. Members of 11 genera and 15 species of bacteria were isolated once.