Sterile Capsule–Egg Cocoon Covering Constitutes an Antibacterial Barrier for Spider Parasteatoda tepidariorum Embryos

The myth of antibiotic spider silk

“…These properties are consistent with the hypothesis that b-silk sheets contributes to providing a physical barrier to microbes. In support of this idea, Babczynska et al (2019) found that silk cases of the spider Parasteatoda tepidariorum placed on broth agar did not inhibit bacterial growth, i.e. showing no antimicrobial effect, whereas in contrast, no bacterial growth was visible when eggs were taken out of the egg case and directly incubated on broth agar.…”

“…underground, and their eggs are always deposited inside a silk case; therefore the deposition of antimicrobial molecules on the silk could function to protect against pathogens. Spider eggs consist of energy-rich compounds and water, which makes them an ideal substrate for pathogens and other microorganisms, therefore it is reasonable to hypothesize that egg case silk (cylindrical and aciniform silk) or the eggs themselves could possess antimicrobial properties ( Babczynska et al., 2019 ; Makover et al., 2019 ). Second, spider silks are protein-based fibers with primarily nonpolar and hydrophobic amino acids ( Romer and Scheibel, 2008 ; Vollrath, 2000 ) that may be targeted as substrate for microbes, therefore requiring antimicrobial properties as defense.…”

Does Only Egg Sac Protect Spider Embryos From Pathogens? Detection Of Antibacterial Proteins In Embryos of Theridiidae And Lycosidae Representatives

“…Research by Wright and Goodacre, (2012) indicates that the web produced by the spider Tegenaria domestica has an inhibitory effect on the growth of Gram (+) bacteria Bacillus subtilis. The lack of observed microorganisms in the cocoon structure con rms the antibacterial silk property and bacterial growth tests showed that no cultivable bacteria had grown in spider eggs samples 19 .…”

“…Samples with empty cocoons were overgrown with several colonies of bacteria and fungi. Tests suggest that eggs inside the cocoon may be sterile 19 . Moreover, young spiders hatched from the eggs used in this study.…”

“…The outer layer has got signi cantly densely packed threads, and an amorphous disks and droplet-like spherites appear between them. Furthermore, no bacterial cells were observed on either layer 19 . Research by Wright and Goodacre, (2012) indicates that the web produced by the spider Tegenaria domestica has an inhibitory effect on the growth of Gram (+) bacteria Bacillus subtilis.…”