Figure 2

TEM images of untreated bagasse showing the following cell wall layers: primary cell wall (PCW), secondary cell wall (SCW) and middle lamella (ML) (Fig. A). Fig. B – higher magnification of SCW showing the cellulose microfibrils orientation. Fig. E, F – SO₂ (190°C/5 min) pretreated cell wall. Large pores with distinct size and shape are observed (Fig. C, asterisks). Compaction of cell wall matrix was visualized forming round and elongated structures (Fig. D, arrows). Fig. C, D – CO₂ (205°C/15 min) pretreated cell wall. After treatment pores (Fig. E, asterisks) and structures formed by compaction of cell wall matrix (Fig. F, arrows) are seen spread at the outer region of secondary cell wall