Abstract
We have noticed that hydroquinone drastically inhibited not only denitrification but also sol respiration. Accordingly, compounds relating with hydroquinone were examined for their effects on growth and activities of varying organisms. p-Benzoquinone not hydroquinone was found to be effective in suppressing denitrification and soil respiration : hydroquinone was oxidized to p-benzoquinone in the soil. In spite of this, resorcinol and o-benzoquinone were not effective. p-Benzoquinone was confirmed to be toxic to both aerobic and anaerobic bacteria but no toxic to yeast and A. oryzae and not inhibitory to germination and growth of plants. These results suggested that p-benzoquinone was toxic only to prokaryotes. In addition, a dark-colored humus-like water-soluble compound, which was produced by heating p-benzoquinone, was also inhibitory to microbial activities. Several implications of these results were discussed in connection with the role of organic matter in the soil ecosystem.
