Fig A: Correlation of gene-expression between samples plotted into a heatmap.

Gene-expression between samples was measured using Pearson’s correlation and plotted into a heatmap. Samples from glucose-grown and chitin-grown conditions (each in triplicate) cluster strongly by condition, indicating high within-condition reproducibility and distinct transcriptional profiles. The data underlying this Figure can be found in S1 Data. Fig B: Principal Component Analysis RNA seq samples. First two principal components are plotted. PCA was performed on normalized gene expression values from glucose-grown and chitin-grown samples, grown for 24 h in liquid cultures (n = 3 per condition). The first two principal components capture the majority of variance across samples. Chitin-grown replicates cluster tightly together, while glucose-grown samples are slightly more dispersed but still primarily separated along the same components, indicating distinct transcriptional signatures between conditions. The data underlying this Figure can be found in S1 Data. Fig C: SEM images of S. venezuelae growing on grasshopper. A) Mycelial sheet covering a significant part of the coxa and femur of the midleg. B) Closer view of the mycelial sheet edge, showing multiple hyphal layers entirely coating the exoskeleton. C) Further magnification of B, depicting an individual hypha navigating between the exoskeleton scales. Scale bar: 25 µM. Fig D: Mycelial aggregates of various Streptomyces species on chitin flakes. Dense mycelial aggregates on chitin flakes isolated from shrimp were observed after two to four days of growth for A) Streptomyces coelicolor; B) Streptomyces avermitilis; C) Streptomyces sp. WAC288; D) Streptomyces sp. WAC303. Scale bar: 50 microns. Fig E. Growth on chitin by Bacillus subtilis, E. coli, P. aeruginosa, and R. jostii. A) Growth curves of B. subtilis in LB and minimal chitin medium, monitored via mCherry fluorescence. B. subtilis shows steady growth in LB, as indicated by increasing fluorescence over time. In contrast, no appreciable increase in fluorescence was observed when B. subtilis was cultured in chitin medium. B) Colony-forming units (CFUs) of E. coli, P. aeruginosa, and R. jostii after incubation in minimal chitin medium chitin and LB (or MYM for R. jostii). Cultures were inoculated with 10⁵ CFUs/mL (indicated by the dotted line) and incubated at 30 °C with shaking for 24 h (E. coli and P. aeruginosa) or 48 h (R. jostii). CFU counts in chitin medium remained stable or declined, whereas in LB/MYM CFUs increased. Data represent the average of three biological replicates with standard deviations. The data underlying this figure can be found in S2 Data. Fig F. Phylogeny and expression of S. venezuelae chitinases. Unrooted tree of various known bacterial GH18 chitinases from subfamilies A, B, and C, including S. venezuelae. Fig H: Colony-forming units (CFUs) of wild-type and mutant strains grown in MYM liquid cultures. Wild-type (WT) strains typically produce an average of 109 CFUs per milliliter in MYM cultures. Mutant strains (KO for knock-out) that are affected during growth on chitin maintain comparable CFUs per microliter on MYM. Bars represent the averages of three biological replicates and the error bars show standard deviations. The data underlying this figure can be found in S2 Data. Fig G: Co-culture of B. subtilis-mCherry with S. venezuelae on MYM. Both wild-type (WT) and the dasBC deletion Streptomyces strains allow growth of B. subtilis on MYM as indicated by the increase of fluorescence signal over time. Datapoints are averages of three biological replicates and the error bars show standard deviations. The data underlying this figure can be found in S2 Data. Fig I: Growth curves B. subtilis-mCherry on LB with Streptomyces venezuelae spent medium concentrate. B. subtilis expressing the red fluorophore mCherry is unable to grow on LB medium supplemented with 25 μg/ml chloramphenicol. Growth on LB with either extracts of chitin medium, or concentrated spend medium of S. venezuelae wild-type (WT) and the dasBC deletion mutant (dasBC KO) grown on chitin grown for 16H, resemble growth comparable to when the bacterium is grown on LB alone. Datapoints are averages of three biological replicates and the error bars show standard deviations. The data underlying this figure can be found in S2 Data. Table A: Strains, plasmids and cosmids used in this study. Table B: Uniprot entries Streptomyces venezuelae chitinases. Table C: primers used in this study. Table D: List of 40 genes that are most significantly upregulated during growth on chitin. Table E: Number of hits in comparative BLASTP analysis of S. venezuelae recombinase RecA, and Vnz_04420 (of the chloramphenicol biosynthetic gene cluster), and chitinases (Chi) in Streptomycetaceae. * Homologs were identified by BLASTp against the NCBI protein database using full-length protein sequences of all identified S. venezuelae chitinases, recombinase Vnz_26845, and Vnz_04420. Inclusion criteria: query coverage 80%–100%, sequence identity 50%–100%, E-value ≤ 1E−05, and a maximum of 5,000 target sequences retrieved.
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