A Repeating Sulfated Galactan Motif Resuscitates Dormant Micrococcus luteus Bacteria

Abstract

Only a small fraction of bacteria can autonomously initiate growth on agar plates. Nongrowing bacteria typically enter a metabolically inactive dormant state and require specific chemical trigger factors or signals to exit this state and to resume growth. has become a model organism for this important yet poorly understood phenomenon. Only a few resuscitation signals have been described to date, and all of them are produced endogenously by bacterial species. We report the discovery of a novel type of resuscitation signal that allows to grow on agar but not agarose plates. Fractionation of the agar polysaccharide complex and sulfation of agarose allowed us to identify the signal as highly sulfated saccharides found in agar or carrageenans. Purification of hydrolyzed κ-carrageenan ultimately led to the identification of the signal as a small fragment of a large linear polysaccharide, i.e., an oligosaccharide of five or more sugars with a repeating disaccharide motif containing d-galactose-4-sulfate (G4S) 1,4-linked to 3,6-anhydro-α-d-galactose (DA), G4S-(DA-G4S) Most environmental bacteria cannot initiate growth on agar plates, but they can flourish on the same plates once growth is initiated. While there are a number of names for and manifestations of this phenomenon, the underlying cause appears to be the requirement for a molecular signal indicating safe growing conditions. has become a model organism for studying this growth initiation process, often called resuscitation, because of its apparent connection with the persistent or dormant form of , an important human pathogen. In this report, we identify a highly sulfated saccharide from agar or carrageenans that robustly resuscitates dormant on agarose plates. We identified and characterized the signal as a small repeating disaccharide motif. Our results indicate that signals inherent in or absent from the polysaccharide composition of solid growth media can have major effects on bacterial growth.

Inhibitory Effect of Depolymerized Sulfated Galactans from Marine Red Algae on the Growth and Adhesion of Diarrheagenic Escherichia coli

“…This hypothesis was supported by previous studies, in which Cordyceps cicadae polysaccharide was also believed to serve as nutrition for E• coli growth after 24 h cultivation [27,28]. However, according to recent studies, it is reported that sulfated galactans are required for growth of Gram-positive Micrococcus luteus [29]. Therefore, the effects of sulfated polysaccharide on different microorganisms remain to be further studied.…”

Comparative Genomics Reveals Broad Genetic Diversity, Extensive Recombination and Nascent Ecological Adaptation in Micrococcus luteus

“…The history of knowledge of M. luteus could date back to 1922, when Fleming used it to prove the lytic activity of lysozyme found in body secretions and tissues [4,5]. Since then, M. luteus was gradually used in a variety of scienti c elds [6][7][8][9][10]. One of the most famous application is resuscitating and stimulating the protein called resuscitation-promoting factor (Rpf), which could promote the resuscitation and growth of some bacteria by autocrine and paracrine signalling functions (e.g., Mycobacterium, Arthrobacter, Bacillus, Streptomyces, etc) [14].…”

Antibacterial Activity of Sulfated Galactans from Eucheuma serra and Gracilari verrucosa against Diarrheagenic Escherichia coli via the Disruption of the Cell Membrane Structure

“…The collection and pretreatment of red algae E. serra and G. verrucosa were performed according to the methods used in an earlier study [ 18 ]. The sulfated galactans from E. serra were extracted and isolated based on previous studies [ 18 , 30 ]. Briefly, 100 g of the dried E. serra powder were macerated in water at 50 °C for 4 h. Then, the E. serra syrup was filtered through filter cloth, concentrated to 1/4th of the original volume, cooled, and precipitated overnight with three volumes of ethanol at 4 °C.…”