| Summary: | <b> </b>Agro-byproducts can be utilized as effective and low-cost nutrient sources for microbial fermentation to produce a variety of usable products. In this study, wheat bran powder (WBP) was found to be the most effective carbon source for xylanase production by <i>Streptomyces thermocarboxydus</i> TKU045. The optimal media for xylanase production was 2% (<i>w/v</i>) WBP, 1.50% (<i>w/v</i>) KNO<sub>3</sub>, 0.05% (<i>w/v</i>) MgSO<sub>4</sub>, and 0.10% (<i>w/v</i>) K<sub>2</sub>HPO<sub>4</sub>, and the optimal culture conditions were 50 mL (in a 250 mL-volume Erlenmeyer flask), initial pH 9.0, 37 °C, 125 rpm, and 48 h. Accordingly, the highest xylanase activity was 6.393 ± 0.130 U/mL, 6.9-fold higher than that from un-optimized conditions. <i>S. thermocarboxydus</i> TKU045 secreted at least four xylanases with the molecular weights of >180, 36, 29, and 27 kDa when cultured on the WBP-containing medium. The enzyme cocktail produced by <i>S. thermocarboxydus</i> TKU045 was optimally active over a broad range of temperature and pH (40–70 °C and pH 5–8, respectively) and could hydrolyze birchwood xylan to produce xylobiose as the major product. The obtained xylose oligosaccharide (XOS) were investigated for 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and the growth effect of lactic acid bacteria. Finally, the solid waste from the WBP fermentation using <i>S. thermocarboxydus</i> TKU045 revealed the high adsorption of Congo red, Red 7, and Methyl blue. Thus, <i>S. thermocarboxydus</i> TKU045 could be a potential strain to utilize wheat bran to produce xylanases for XOS preparation and dye adsorbent.
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