Bacterial inducible expression of plant cell wall-binding protein YesO through conflict between Glycine max and saprophytic Bacillus subtilis

Abstract

Saprophytic bacteria and plants compete for limited nutrient sources. Bacillus subtilis grows well on steamed soybeans Glycine max to produce the fermented food, natto. Here we focus on bacterial responses in conflict between B. subtilis and G. max. B. subtilis cells maintained high growth rates specifically on non-germinating, dead soybean seeds. On the other hand, viable soybean seeds with germinating capability attenuated the initial growth of B. subtilis. Thus, B. subtilis cells may trigger saprophytic growth in response to the physiological status of G. max. Scanning electron microscope observation indicated that B. subtilis cells on steamed soybeans undergo morphological changes to form apertures, demonstrating cell remodeling during saprophytic growth. Further, transcriptomic analysis of B. subtilis revealed upregulation of the gene cluster, yesOPQR, in colonies growing on steamed soybeans. Recombinant YesO protein, a putative, solute-binding protein for the ATP-binding cassette transporter system, exhibited an affinity for pectin-derived oligosaccharide from plant cell wall. The crystal structure of YesO, in complex with the pectin oligosaccharide, was determined at 1.58 Å resolution. This study expands our knowledge of defensive and offensive strategies in interspecies competition, which may be promising targets for crop protection and fermented food production.

Disentangling the genetic basis of rhizosphere microbiome assembly in tomato

“…In particular, alphagalactosidase (B2R_16136) and arabinose import (B2R_29105) had the highest LOD and smallest overlapping confidence intervals with chromosomes 6 and 11 (Figure 7). Indeed, many SNPs in genes involved in the degradation of xylan 58 , one of the most dominant non-cellulosic polysaccharides in plant cell-walls 59 , as well as carbohydrate and protein metabolism were linked to chromosomes 6 and 11, including xyloglucanase Xgh74A (B2R_10589), alpha-xylosidase (B2R_23763), endo-1,4-beta-xylanase (B2R_20609), extracellular exo-alpha-Larabinofuranosidase (B2R_20608), multiple protease HtpX (B2R_19218), cutinase (B2R_19356), and putative ABC transporter substrate-binding protein YesO (B2R_09821) which has been implicated in the transport of plant cell wall pectin-derived oligosaccharides 60 . A Streptomyces SNP in acetolactate synthase (B2R_28001) was linked to chromosome 6 where a plant acetolactate synthase was located.…”

Bacteria with a mouth: Discovery and new insights into cell surface structure and macromolecule transport

“…In 2020, we found that Bacillus cells can form a “hole”-like structure in their cell surface 115 ) during growth on solid media. Briefly, when the cells of B. subtilis 168 were grown in a nutrient medium solidified with agar, the cells shrank at the end of growth ( Fig.…”

“…A1, 120 – 123 ) PVA-degrading enzymes in Sphingopyxis sp. 113P3, 112 – 114 ) and plant cell wall (pectin)-degrading enzymes in B. subtilis , 115 , 124 − 132 ) respectively. In other words, applied studies led to the discovery of novel basic biological phenomena, which will expand and develop new areas of microbiology and bioscience.…”

Accelerated Alcoholic Fermentation of Intact Grapes by Saccharomyces Cerevisiae in Symbiosis with Microbial Community Inhabiting Grape-skin

“…Among pectin-degrading enzymes, polygalacturonase is genetically encoded and expressed by grape-skin resident species and by S. cerevisiae 42,43 . Recently, we revealed the importance of pectin as an initial target for the saprophytic bacterium Bacillus subtilis to recognize the surface of dead soybeans 44 , whereas it is unlikely that pectin degradation by non-Saccharomyces microorganisms specifically accelerated alcoholic fermentation of intact grapes. As shown in Fig.…”