Bacteria inhabiting spider webs enhance host silk extensibility

Area of Science:

• Biomaterials Science
• Microbiology
• Biotechnology

Background:

• Spider silk possesses remarkable mechanical properties, making it attractive for biomedical applications.
• The microbial communities on spider webs and their interactions with silk remain largely unexplored.

Purpose of the Study:

• To investigate the impact of exopolysaccharide-secreting bacteria from spider webs on major ampullate (MA) silk properties.
• To determine the role of silk surface layers in mediating bacterial-silk interactions.

Main Methods:

• Orb spider web-derived bacteria (Microbacterium sp., Novosphigobium sp.) were exposed to Triconephila clavata MA silk.
• MA silk with and without surface layers was analyzed after bacterial exposure.
• Silk extensibility was measured, and exopolysaccharide presence was confirmed via NMR.

Main Results:

• Bacterial exposure significantly increased MA silk extensibility by 58.7%.
• This enhancement was abolished when silk surface lipid and glycoprotein layers were removed.
• Exopolysaccharides were detected on MA silk exposed to bacteria, but not on unexposed silk.

Conclusions:

• Exopolysaccharide-secreting bacteria inhabiting spider webs can enhance the extensibility of host MA silk.
• The natural surface layers of MA silk are crucial for mediating this bacterial-induced enhancement.