Each experiment was repeated three to four times and one standard deviation is shown. The structures of Trp, Ind, IAA, I3CA, IAN, I3A, TM, and OI are shown. The asterisk indicates statistical significance determined using a Student Ro 61-8048 datasheet t test (P < 0.05). Most interestingly, a plant auxin, 3-indolylacetonitrile dramatically (up to 2900-fold) decreased the heat-resistant CFU of P. alvei in a dose dependent manner at 16 and 30 hr (Figure 2B and Figure 4A), while another auxin 3-indoleacetic acid had a less significant influence,

and tryptamine and 2-oxindole had no effect (Figure 4A). Therefore, these results suggest that the functional groups of indole derivatives may control the development of P. alvei spores. Similar to indole, the proportion of sporulating cells in the total click here number of cells was similar with

and without treatment of 3-indolylacetonitrile (upper panel in Figure 3). Also, 3-indolylacetonitrile produced an irregular spore coat, while no treatment produced sturdy coat (Figure 3). Therefore, it appeared that indole and 3-indolylacetonitrile inhibited spore maturation rather than sporulation initiation. In order to understand how most spores (upper panel in Figure 3) in the presence of indole and 3-indolylacetonitrile could not survive against heat treatment, the lysozyme resistance assay [36] was performed with 30-hour grown cells since the lysozyme treatment could release all spores. As a result, indole and 3-indolylacetonitrile

produced a large portion of lysozyme-resistant PND-1186 mw cells (47 ± 8% with indole and 50 ± 3% with 3-indolylacetonitrile) which are probably the number of total spores, while indole and 3-indolylacetonitrile produced only 6.7 ± 0.9% and 1.5 ± 0.1% heat-resistant cells (Figure 2C); hence it appeared that a large number of spores have some spore defect for heat resistance. Therefore, it appeared that the low heat-resistant CFU was caused by some spore defect or the altered spore structure. Furthermore, the effect of indole and 3-indolylacetonitrile was investigated using another spore-forming medium, Brain Heart Infusion (BHI) agar for a longer incubation time (here, 14 days) when sporulation process would be completed. Similar to DSM medium, indole (1 mM) and 3-indolylacetonitrile (1 mM) inhibited the heat-resistant CFU of P. alvei (17 ± 10% and 16 ± 1%), compared to no addition of exogenous Carnitine palmitoyltransferase II indole (77 ± 3%). Therefore, the inhibitory impact of indole and 3-indolylacetonitrile was effective in different media for a long term, while their effect on heat resistance was attenuated with a longer incubation time. Effect of indole and indole derivatives on cell growth To test the toxicity of indole and indole derivatives, cell turbidity at 16 hr and the specific growth rates with indole and 3-indolylacetonitrile were measured. Most indole derivatives at the concentration tested (1 mM) did not have much of an inhibition effect on the cell growth of P.