Table 1.

Identities and provenances of bacterial strains used in this study.

Isolate ID	Bacterial culture details	Provenance	Chitinolytic activity detectedb	Sporulation of Polysphondylium observed in association with the bacteriac	Taxonomic affiliation by 16S rRNA gene fragment sequencing (sequence similarity of closest match in GenBank)
1	Isolate D22	Isolated from grassland soil, Czech Republic	Yes	n.a.	Janthinobacterium sp. (100%), Oxalobacteraceae, β-proteobacteria
2	Isolate D23	Isolated from grassland soil, Czech Republic	Yes	Yes, abundant	Janthinobacterium sp. (100%), Oxalobacteraceae, β-proteobacteria
5	Paenibacillus chitinolyticus CCM 4527	Public culture collection, originally isolated from forest soil, Japan	Yes	Yes, abundant	Paenibacillus sp. (100%), Paenibacillaceae, Firmicutes
8	Isolate M-N	Isolated from a mycorrhizal inoculum pota	No	No	Gordonia sp. (100%), Nocardiaceae, Actinobacteria
9	Isolate M-R	Isolated from a mycorrhizal inoculum pota	No	n.a.	Rhodococcus sp. (100%), Nocardiaceae, Actinobacteria
10	Isolate NM-A	Isolated from a non-mycorrhizal inoculum pota	No	n.a.	Arthrobacter sp. (99%), Micrococcaceae, Actinobacteria
12	Isolate M-F	Isolated from a mycorrhizal inoculum pota	No	Yes	Bacillus sp. (94%), Bacillaceae 1, Firmicutes
13	Isolate M-U	Isolated from a mycorrhizal inoculum pota	No	No	Mycobacterium sp. (99%), Mycobacteriaceae, Actinobacteria
15	Isolate NM-H	Isolated from a non-mycorrhizal inoculum pota	No	Yes	Rhodococcus sp. (100%), Nocardiaceae, Actinobacteria
16	Isolate NM-O	Isolated from a non-mycorrhizal inoculum pota	No	n.a.	Nocardia sp. (100%), Nocardiaceae, Actinobacteria
17	Paenibacillus ehimensis CCM 4526	Public culture collection, originally isolated from garden soil, Japan	Yes	Yes, abundant	Paenibacillus sp. (100%), Paenibacillaceae, Firmicutes

n.a. not analysed.

^aIsolated using yeast extract agar supplemented with colloidal chitin.

^bSee supplementary Figs. S1, S2 and S3 for details.

^cSee supplementary Fig. S6 for photos.