Cellulose is a polysaccharide predominantly found in the extracellular matrices of plants, algae and bacteria [1], with urochordates being the sole cellulose-producing animals [2]. In plants, cellulose microfibrils in primary and secondary cell walls adopt tightly ordered arrangements, enhancing structural rigidity [3]. Cell wall synthesis is important for microorganisms, though cellulose is not universally present across all microbial species. But their molecular mechanisms are poorly understood [4]. Compared to plant cellulose, bacterial cellulose does not contain other plant cell wall components, such as lignin and hemicellulose and therefore is of higher purity [5]. However, the bacterial cellulose synthase enzyme does not require primers, so it is relatively easier to isolate and purify [6]. Meanwhile, bacterial cellulose has the advantage of high crystallinity, high tensile strength and a high modulus of elasticity [2]. Currently, multiple genera have been confirmed to produce bacterial cellulose [7]. Enhancing bacterial cellulose production has become a key industrial focus, contributing to both mechanistic understanding and large-scale applications [8]. Concurrently, elucidating plant cellulose biosynthesis is crucial for improving yield and supporting sustainable utilization.

Fig. 1 illustrates research hotspots via keyword co-occurrence analysis. Node size corresponds to keyword frequency while connecting lines indicate co-occurrence relationships (line thickness reflects association strength). Specifically, the blue clusters in the figure focus on the study of the association between cellulose and cell wall synthesis. The green clusters, on the other hand, delve into the role of cellulose in wood formation, especially in the biosynthesis of primary and secondary walls of xylem. And it can be seen that cellulose synthase, cellulose biosynthesis, and gene expression are the keywords with the highest frequency of occurrence. The yellow cluster focuses on bacterial cellulose and encompasses bacterial cellulose biosynthesis. Finally, the red clustering brings together the research hotspots in the field of plant cellulose synthesis, in which the key role of cellulose synthase complex in the process of cellulose synthesis is also reflected. Therefore, this review focuses on plant cellulose, bacterial cellulose, and their biosynthesis.

Cellulose, composed of β-1,4-D glucan monomers [9], is polymerized at the plasma membrane by CSCs. In bacteria, linear terminal complexes (TCs) are observed at growing microfibril ends [10]. In plants, CSCs form rosette-shaped TCs, as confirmed by immunogold labeling [11]. The synthesis of cellulose in plants is different from that of bacterial cellulose. CSCs catalyze the formation of cellulose molecular chains and enable their exportation to the periplasm [12]. Molecular biology studies have shown that CSCs consist of multiple cellulose synthase subunits, known in bacteria as bacterial cellulose synthase subunits [13]. In bacteria, cellulose synthesis typically includes BcsA and BcsB as the catalytic core while plant CSCs comprise multiple CesA isoforms. Cellulose synthesis in plants is regulated by CSCs assembly, transport, and gene expression [14], and is influenced by environmental factors such as pH, temperature, and nutrient availability.

Although numerous excellent reviews have separately detailed the mechanisms of cellulose biosynthesis in plants or bacteria, a systematic and comparative analysis that highlights the convergent and divergent strategies employed by these two kingdoms is relatively scarce. This review aims to fill this gap by providing a side-by-side comparison of the synthesis machinery, focusing on the core and auxiliary components, and critically evaluating the challenges in recapitulating the native process, particularly the biosynthesis of cellulose I, in vitro.