Research Article: Staphylococcus aureus aggregation in the plasma fraction of silkworm hemolymph

Date Published: May 30, 2019

Publisher: Public Library of Science

Author(s): Hiroki Ryuno, Fuki Nigo, Isao Naguro, Kazuhisa Sekimizu, Chikara Kaito, Erjun Ling.


Staphylococcus aureus formed bacterial aggregates in the plasma fraction of the hemolymph of silkworm, the larva of Bombyx mori, in a growth-dependent manner. The addition of arabinose or galactose inhibited the formation of S. aureus aggregates in the silkworm plasma. Formation of the bacterial aggregates depended on S. aureus genes required for the synthesis of bacterial surface polysaccharides–ypfP and ltaA, which are involved in lipoteichoic acid synthesis, and the tagO gene, which is involved in wall teichoic acid synthesis. These findings suggest that S. aureus forms bacterial aggregates in the silkworm plasma via bacterial surface teichoic acids.

Partial Text

Staphylococcus aureus is a human pathogenic bacterium that exists in the nares of 30% healthy persons and causes various diseases such as pneumonia, meningitis, and sepsis in immunocompromised patients. Since the 1960s, methicillin-resistant S. aureus (MRSA) has infected many people in hospitals and clinical care facilities, and a new type of MRSA, called community-acquired MRSA, has emerged in the last two decades, infecting healthy persons in the general population [1]. Overcoming S. aureus infectious diseases will require a comprehensive understanding of the detailed molecular mechanisms underlying S. aureus virulence.

The present study demonstrated that S. aureus forms bacterial aggregates in silkworm plasma in vitro, which is the first indication that S. aureus bacterial aggregates in animal plasma is not specific to mammals, but is conserved in insects.




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