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Thermostable and alkalitolerant xylanases have got intense research focus due to their vast applications in various industries including pulp and paper, food, feed, textile, biofuel, etc. In the present investigation, a Penicillum sp. SS1 isolated from degrading woody material was found to produce moderately thermoactive and alkalistable endo-β-1,4-xylanase (xylanase). Maximum xylanase production was observed after fourth day of fermentation (43.84 IU/ml). The organism produced substantial quantities of xylanase using agricultural residues like wheat bran (20.6 IU/ml), rice bran (21.8 IU/ml) and sawdust (10.7 IU/ml) as carbon sources. The enzyme preparation was totally free of filter paper activity (FPase) and possessed negligible carboxymethyl cellulase (CMCase) activity; this could be an important feature of enzyme if the intended application of enzyme is in pulp and paper industries. Among nitrogen sources examined, yeast extract supported maximum xylanase production (45.74 IU/ml), and was followed by soybean meal (22.2 IU/ml) and ammonium sulphate (20 IU/ml). Maximum xylanase production was observed at initial medium pH 9 (25.6 IU/ml); however, at pH 8 and 10 also significantly high enzyme titre was observed (24 and 21.2 IU/ml, respectively). Thus, Penicillium sp. SS1 displayed capability of growing and producing xylanase at high alkaline pH (8–10). Maximum xylanase activity was reported at 50 °C, however, significantly high activity was observed at 60 °C (65.4%), however, at 70–80 °C activity was lost considerably. At 50–60 °C the enzyme retained very high activity up to 30–60 min (91–100%), however, prolonged incubation (90 min) caused considerable activity reduction (residual activity 63–68%).

Discovery of new/novel enzymes with process-apt features has been a continuous practice. A wide range pH-stable and thermostable xylanase was reported hitherto from a newly isolated fungal strain Aspergillus terreus S9, from mushroom compost. This is the first ever report where-in a pH-stable and thermostable xylanase is being reported from a strain of A. terreus. Solid state fermentation was executed on agro-industrial residues for xylanase production. Maximum xylanase production was supported by wheat bran (40 U/ml), however, substantial xylanase yield was observed on other residues like corn cob powder (38.4 U/ml), cotton cake (38 U/ml), malt (37.6 U/ml) and almond hulls (35.2 U/ml). Almond hulls are being reported for the first time as the substrate for xylanase production. Plackett-Burman design was used to earmark the most effective process variables (wheat bran, medium pH, and incubation time), and the same were optimized by design of experiments (DoE) based on response surface methodology to achieve a yield enhancement of 1.82-fold. A. terreus S9 xylanase exhibited an excellent and brisk clarification of mosambi and orange juices. DoE based optimization of process parameters (enzyme dose, treatment time and incubation temperature) resulted in 1.23-fold and 1.28-fold enhanced orange and mosambi juice clarification, respectively. Furthermore, admirable dough raising capacity and pulp brightening ability of A. terreus S9 xylanase shows its promising potential for bread making, and eco-friendly biobleaching processes, respectively. The xylanase must be in-depth investigated to decipher the molecular mechanisms of diverse applications.

High production cost and lack of process‐suitable characteristics in available microbial xylanases limit their vast industrial application potential. A new strain of Aspergillus terreus S9 isolated from mushroom compost (Directorate of Mushroom Research, Solan, India), utilized agro‐industrial wastes as substrates for growth, and produced a process‐apt xylanase. The study is the first ever report of a thermostable (60–90°C) and broad range pH stable (6.0–10.0) xylanase from a strain of Aspergillus terreus. Of a total of ten process variables examined based on Plackett‐Burman design, four variables, i.e., wheat bran, incubation time, pH, and CaCl2 were earmarked to have substantial influence on xylanase production. These selected four variables were further optimized using Design of Experiments (DoE) approach (response surface methodology), and xylanase yield was enhanced (1.92‐fold). Saccharification potential of xylanase was assessed using rice straw as substrate, under several sets of combinatorial regimes. Results showed that alkali pretreatment (0.2M KOH) followed by acid pretreatment (1% sulphuric acid) and enzymatic hydrolysis with cellulase and xylanase yielded maximum sugars. Desired industrial traits of A. terreus S9 xylanase reflect its application prospective for valorization of lignocellulosic biomass for production of biofuel‐ethanol/other industrial products. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1210–1219, 2018