Preservation of Ceriporiopsis subvermispora and Lentinula edodes treated wheat straw under anaerobic conditions

Abstract

Background: No attention has been paid so far to the preservation of fungal-treated lignocellulose for longer periods. In the present study, we treated wheat straw (WS) with the white-rot fungi Ceriporiopsis subvermispora and Lentinula edodes for 8 weeks and assessed changes in pH, chemical composition and in vitro gas production (IVGP) weekly. Fungal-treated WS was also stored for 64 days 'as is', with the addition of lactic acid bacteria (LAB) or with a combination of LAB and molasses in airtight glass jars mimicking ensiling conditions.

Results: Both fungi significantly reduced the lignin and hemicellulose content of WS, and increased the cellulose content. The IVGP increased with increasing time of incubation, indicating the increase in digestibility. Both fungi lowered the pH of WS under 4.3, which guarantees an initial and stable low pH during anaerobic storage. Minor changes in fibre composition and IVGP were observed for stored L. edodes treated WS, whereas no change occurred for C. subvermispora.

Conclusion: It is possible to conserve C. subvermispora and L. edodes treated straw under anaerobic condition without additives up to 64 days. This finding is important for practical application to supply fungi-treated feed to ruminant animals for a prolonged period. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Keywords: Ceriporiopsis subvermispora; Lentinula edodes; anaerobic storage; in vitro gas production; wheat straw.

Figure 1

pH value of wheat straw (WS), autoclaved wheat straw (AWS), C. subvermispora treated AWS (CS + AWS) and L. edodes treated AWS (LE + AWS) for 0–8 weeks (week 0 represents AWS inoculated with spawn without incubation). Error bars indicate the SD.

Figure 2

Total gas production after 72 h of wheat straw (WS), autoclaved wheat straw (AWS), C. subvermispora treated AWS (CS + AWS) and L. edodes treated AWS (LE + AWS) for 0–8 weeks (week 0 represents AWS inoculated with spawn without incubation). Error bars represent the SD.

Figure 3

pH value of (A) untreated autoclaved wheat straw (AWS) and (B) wheat straw (WS) after 0, 2, 4, 8, 16, 32 and 64 days of storage. Substrates were stored ‘as is’, with the addition of lactic acid bacteria (LAB) or with the addition of a combination of LAB and molasses (LAB + M). Error bars represent the SD.

Figure 4

pH value of autoclaved wheat straw treated with (A) C. subvermispora (CS) and (B) L. edodes (LE) after 0, 2, 4, 8, 16, 32 and 64 days of storage. Substrates were stored ‘as is’, with the addition of lactic acid bacteria (LAB) or with the addition of a combination of LAB and molasses (LAB + M). Treatment of AWS and WS are described in Fig. 3. Error bars represent the SD.