Medium Initial pH and Carbon Source Stimulate Differential Alkaline Cellulase Time Course Production in Stachybotrys microspora

Abstract

The production profile of cellulases of the mutant strain A19 from the filamentous fungus Stachybotrys microspora was studied in the presence of various carbon sources (glucose, lactose, cellulose, carboxymethylcellulose (CMC), and wheat bran) and a range of medium initial pH (5, 7, and 8). Two extracellular cellulases from the Stachybotrys strain (endoglucanases and β-glucosidases) were monitored by enzymatic assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and zymogram analysis. Glucose and lactose repressed CMCase time course production while they permitted a strong β-glucosidase one. On Avicel cellulose, CMC, and wheat bran, both activities were highly produced. Wheat bran (WB) is the best carbon source with an optimum of production at days 5 and 6. The production kinetics of both activities were shown to depend on the medium initial pH, with a preference for neutral or alkaline pH in the majority of conditions. The exception concerned the β-glucosidase which was much more produced at acidic pH, on glucose and cellulose. Most interestingly, a constitutive and conditional expression of an alkaline endoglucanase was revealed on the glucose-based medium at an initial pH of 8 units. The zymogram analysis confirmed such conclusions and highlighted that carbon sources and the pH of the culture medium directed a differential induction of various endoglucanases and β-glucosidases.

Optimization of cultivation conditions in banana wastes for production of extracellular β-glucosidase byTrichoderma harzianumRifai efficient forin vitroinhibition ofMacrophomina phaseolina

“…The critical values that represented the maximum b-glucosidase activity as high as 1483.27 U/mL were observed when the amount of carbon source and pH were increased up to a certain extent, at approximately 10% (w/v) and pH 7.3, respectively ( Figure 5). The outcome seen here is reflected in its positive value (+142.75BD) ( Table 2) and corroborated an earlier study by Al-Jazairi et al [52], in which the activity of b-glucosidase produced by Brettanomyces lambics was the highest when the fungus was cultured at both high pH and high content of carbon source.…”

The Hybrid Strategy of Thermoactinospora rubra YIM 77501T for Utilizing Cellulose as a Carbon Source at Different Temperatures

“…It revealed that expression of some cellulase genes may need some special induced conditions and there may be expression of some cellulase genes under presence of other carbon source, like glucose. For Stachybotrys microspore A19, carbon sources and the pH of the culture medium can direct a differential induction of various cellulases (such as endoglucanases and beta-glucosidases; Ben Hmad et al, 2014). …”

Improvement of cellulase and xylanase production by solid‐state fermentation of Stachybotrys microspora

“…Biochemical results showed that higher rates of enzyme activities were obtained for a basic pH of about 8 [15]. However, for the first condition (W1), we kept the pH neutral.…”