Staphylococcus aureus aggregation in the plasma fraction of silkworm hemolymph.

Hiroki Ryuno,Kazuhisa Sekimizu,Chikara Kaito,Isao Naguro,Fuki Nigo

doi:10.1371/journal.pone.0217517

Hiroki Ryuno, Kazuhisa Sekimizu + Show 3 more

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https://doi.org/10.1371/journal.pone.0217517

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Abstract

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.

Highlights

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
The precipitates were not observed when S. aureus was cultured in tryptic soy broth (TSB) or S. aureus was not inoculated into silkworm plasma (Fig 1A)
The precipitates were collected by low centrifugation (70 g for 5 min), whereas the planktonic S. aureus cells in TSB was not collected by this centrifugation condition (Fig 1B)

Summary

Introduction

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. Overcoming S. aureus infectious diseases will require a comprehensive understanding of the detailed molecular mechanisms underlying S. aureus virulence. S. aureus forms aggregates in mammalian blood plasma, which is called the “coagulase reaction” [2]. The coagulase reaction is an important clinical feature for identifying S. aureus [3,4,5]. Clarification of the molecular mechanism of the aggregation reaction of S. aureus in animal blood plasma is important for understanding S. aureus virulence. Many molecular aspects of the coagulase reaction in mammalian plasma have been studied, it has remained unclear whether S. aureus forms aggregates in the plasma fraction from animals other than mammals

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