Wild-type bacterial silk: a next-gen biomaterial beyond silkworm and spider silks

This review examines bacterial silk (BNES) from Bacillus sp. strain NE as a next-generation biomaterial, showcasing its unique structural and functional properties compared to silkworm and spider silks. BNES exhibits an amino acid profile with elevated proline (16.61%), cysteine (1.85%), and histidine (5.42%), promoting flexibility, disulfide bonding, and metal coordination. Structural analysis reveals predominantly β-sheet (45%) and random coil (50%) conformations, with FTIR and NMR confirming unique S-S (605.67/551.66 cm⁻¹) and metal-ligand (2148.77 cm⁻¹) peaks. Thermal studies indicate a lower glass transition temperature (138 °C) and greater water loss (~ 30% at 140 °C) than silkworm and spider silks, reflecting differences in thermal stability and hydrophobicity (0.45 for BNES vs. -0.25 and − 0.35 for silkworm and spider silks). Functional analysis of BNES-derived sericin (10% yield) reveals strong antioxidant (IC50 0.38–0.41 mg/mL), anticancer (IC50 0.51–0.83 mg/mL), antimicrobial (MIC ≤ 1.33 mg/mL), and antiviral (IC50 4.1 µg/mL for HSV-1) activities. While challenges in large-scale production and regulatory approval remain, advancements in metabolic engineering and fermentation optimization show promise. BNES’s versatility and superior bioactivities position it as a sustainable biomaterial for applications in tissue engineering, drug delivery, water remediation, and advanced material design, offering distinct advantages over traditional silks.