Biology subjects

Tashiro, Y.

Publications and source records attributed to Tashiro, Y..

10 recordsLinked to original sources

bioRxiv2026

Fluorescence in situ hybridization reveals endophytic and epiphytic root colonization of the novel plant growth-promoting bacterium Citrobacter sedlakii CESi7

Plant growth-promoting bacteria are gaining significant attention as promising biofertilizers. However, the inconsistency between in vitro plant growth-promoting traits and actual field performance remains a challenge, driven partly by a limited understanding of in situ colonization. This study characterized the colonization patterns of Citrobacter sedlakii CESi7, a novel plant growth-promoting bacterium, isolated from oil palm waste compost, during Brassica rapa cultivation. The in situ behavior of CESi7 was observed in both sterilized medium and non-sterilized soil using fluorescence in situ hybridization with a strain-targeting probe. The results revealed that CESi7 can establish both epiphytic and endophytic populations that transiently colonize roots. In a sterilized medium, CESi7 was widely distributed throughout the root tissues. Conversely, in non-sterilized soil, the bacterium formed dense aggregates specifically at the root tips. This study provides direct microscopic evidence of the colonization strategy of CESi7, offering crucial insights for its development as an effective biofertilizer.

microbiology↗

bioRxiv2026

Fermented Botanical Product Modulates Soil Bacterial Communities and Enhances Plant-Growth-Promoting Activity for Sustainable Agriculture

Although biostimulants have attracted attention for sustainable agricultural systems, their efficacy remains poorly understood. In this study, we evaluated the effects of fermented botanical product (FBP) produced by fermenting and aging 41 types of fruits, grains, seaweed, and root vegetables with brown sugar for more than three years. Three crops, tomato, rice, and komatsuna (Brassica rapa), were cultivated with the application of 5,000- or 10,000-fold diluted FBP in greenhouses or fields. Application of diluted FBP promoted plant growth, as indicated by increased fresh weights of shoots, leaves, and roots, fruit production in tomato, and rice husk yield. As diluted FBP contained low nutrient levels, an indirect mechanism of plant growth promotion was suggested. Bacterial community structure analysis indicated changes in alpha diversity, beta diversity, and the predominant phyla in FBP-applied soils without plants and in soils cultivated with tomato, rice, and komatsuna. In addition, the abundance of plant-growth-promoting bacteria, such as Arthrobacter, Pseudomonas, Paraburkholderia, and Planifilum, increased in soils treated with diluted FBP. Furthermore, ammonium formation activity was observed in komatsuna cultivation soils treated with diluted FBP, whereas phosphate-solubilizing activity was enhanced in soils from all three crop cultivation systems treated with diluted FBP. These results suggest that diluted FBP influences bacterial communities and promotes crop growth through indirect effects, including increases in plant-growth-promoting bacteria, ammonium production, and phosphate solubilization. Alternatively, FBP may directly stimulate plant growth. Therefore, FBP may be a useful biostimulant for sustainable agricultural systems. HighlightsO_LIDiluted FBP promoted the growth of tomato, rice, and komatsuna (Brassica rapa). C_LIO_LIDiluted FBP altered the bacterial community structure in cultivated soils. C_LIO_LIFBP increased the abundance of plant-growth-promoting bacteria in cultivated soils. C_LIO_LIFBP stimulated ammonium formation and phosphate solubilization in cultivated soils. C_LIO_LIFBP may be a useful biostimulant for sustainable agricultural systems. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/728655v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@4772dorg.highwire.dtl.DTLVardef@12c40e8org.highwire.dtl.DTLVardef@594513org.highwire.dtl.DTLVardef@c5e5a6_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2026

Competition-induced metabolic switching governs the interaction network in plant microbiome assembly

Plants are colonized by characteristic microbiomes that help maintain plant health and function. However, the mechanisms that make these communities assemble in a consistent, repeatable manner remain poorly understood. Here, we show how microbial metabolic strategies for host-derived substrates drive plant microbiome assembly, using a six-member synthetic community that captures the taxonomic diversity of natural duckweed microbiome. Contrary to expectations of metabolic niche partitioning, five of six strains adopt similar metabolic states when colonizing the host alone, consistent with the preferential use of a shared substrate, acetaldehyde. In contrast, during competition with specific community members, these strains consistently switch toward alternative substrates, including sugars and aromatics. Strikingly, this metabolic switching accompanies all negative interspecies interactions observed in the community, indicating that a single class of metabolic response dominates the inhibitory interaction network organizing community structure. By comparison, although metabolite cross-feeding is widespread, its contribution to facilitative interactions depends on the background of resource competition. Together, these findings highlight competition-induced metabolic switching as a primary driver of microbial interaction networks, and provide a cross-scale account of how microbial metabolic strategies underpin the reproducible assembly of plant microbiomes.

microbiology↗

bioRxiv2025

Kinetic modeling of continuous meta-fermentation quantifies metabolic activity in a complex microbial system

One of the serious drawbacks of a complex microbial system is the difficulty in quantifying the metabolic activity of each microorganism. A kinetic model of predominant microbial species was constructed for continuous meta-fermentation in a complex microbial system at several dilution rates (D). The introduction of biomass and lactic acid inhibition terms improved model accuracies at D = 0.05 h-1 and 0.4 h-1, respectively. The coefficient of determination (R2) and root mean square error (RMSE) improved from 0.577 and 5.21 to 0.972 and 0.759, respectively, with the inhibition term at D = 0.05 h-1. The inhibition terms resulted in good R{superscript 2} (0.996) and RMSE (1.27) values at D = 0.4 h-1. By solving the Michaelis-Menten equation in the constructed models, the species flux (SF) was calculated to estimate the metabolic activity (formation and consumption) of each microorganism. At D = 0.05 h-1, Caldibacillus hisashii contributed to lactic acid production at 0.333 g/L/h, whereas Clostridium cochlearium consumed lactic acid at 0.203 g/L/h, suggesting cross-feeding of a metabolite. It is therefore possible to account for consumption that cannot be considered in gene-derived calculations, indicating that this is a promising analytical method for investigating the dynamic behavior of complex microbial systems. Kinetic models for continuous meta-fermentation at several D values were developed. A new metabolic analysis method is proposed to estimate the activity of microbial species in a complex microbial system.

bioinformatics↗

bioRxiv2023

Rechargeable Biomineral Induced by Sulfate Reducing Bacterium Cupidesulfovibrio sp. HK-II

A black precipitate produced by a sulfate reducing bacterium Cupidesulfovibrio sp. strain HK was investigated with multidisciplinary methods. X-ray diffraction (XRD) analysis revealed that the black precipitate was mackinawite. Cyclic voltammetry analysis showed the obvious redox peaks, and the biogenic mackinawite exhibited rechargeable properties. XRD analyses showed that the form of the rechargeable biogenic mackinawite (RBM-II) was changed by discharge and recharge treatments: Field-emission transmission electron microscope analyses revealed that lepidocrocite and amorphous iron oxide were appeared from mackinawite on discharged condition, and the three kinds of minerals were intermingled via the rechargeable treatments. Physicochemical parameters were changed regularly under the treatments, suggesting that discharge would be occurred by iron oxidation and sulfur reduction, and vice versa. These results indicated that dynamics of sulfur is important key process in rechargeable mechanism, supporting that a part of mackinawite was transformed to lepidocrocite and iron oxides, and vice versa. Microbial fuel cells (MFCs) equipped with lactate, strain HK-II and anode including RBM-II consumed lactate even under opened circuit conditions, after which MFCs generated higher current density at re-closed circuit conditions. These results demonstrated that the biogenic mackinawite is one of rechargeable materials and would play important roles in geomicrobiological reactions and biotechnology.

bioengineering↗

bioRxiv2023

Learning beyond-pairwise interactions enables the bottom-up prediction of microbial community structure

The way to deal with higher-order effects (i.e., modification of pairwise interactions by third-party species) has been a major consideration in community ecology. Ignoring these effects is not in line with reality, yet fully considering them make the situation overly complex. Here, we propose a simple framework incorporating higher-order effects into a bottom-up community modeling, and assessed its validity using a seven-member synthetic bacterial community on a host plant, duckweed. Our findings revealed that actual interspecies interactions in community could not be predicted from pairwise co-culturing results; however, using information from trio combinations allowed for acceptable prediction. In addition, inclusion of four-, five-, and six-member combinations did not markedly enhance the prediction accuracy from trio-based prediction, suggesting that trio combinations, the smallest unit of higher-order effects, provide a reasonable baseline to unravel complex interaction networks. Building on this finding, we developed a prediction rule to estimate the structure of 4 - 7 member communities based on information from [≤] 3-member combinations, which yielded significantly better accuracy (relative mean square percentage errors of 22.7% - 61.2%) than pairwise-based model (53.5% - 185.2%). This highlights the possibility of establishing a quantitative link between the interspecies interactions and community structure, by observing beyond-pairwise combinations.

ecology↗

bioRxiv2021

A glycosylphosphatidylinositol-anchored α-amylase encoded by amyD contributes to a decrease in the molecular mass of cell wall α-1,3-glucan in Aspergillus nidulans

-1,3-Glucan is one of the main polysaccharides in the cell wall of Aspergillus nidulans. We previously revealed that it plays a role in hyphal aggregation in liquid culture, and that its molecular mass (MM) in an agsA-overexpressing (agsAOE) strain was larger than that in an agsB-overexpressing (agsBOE) strain. The mechanism that regulates the MM of -1,3-glucan is poorly understood. Although the gene amyD, which encodes glycosyl-phosphatidylinositol (GPI)-anchored -amylase (AmyD), is involved in the biosynthesis of -1,3-glucan in A. nidulans, how it regulates this biosynthesis remains unclear. Here we constructed strains with disrupted amyD ({Delta}amyD) or overexpressed amyD (amyDOE) in the genetic background of the ABPU1 (wild-type), agsAOE, or agsBOE strain, and characterized the chemical structure of -1,3-glucans in the cell wall of each strain, focusing on their MM. The MM of -1,3-glucan from the agsBOE amyDOE strain was smaller than that in the parental agsBOE strain. In addition, the MM of -1,3-glucan from the agsAOE {Delta}amyD strain was greater than that in the agsAOE strain. These results suggest that AmyD is involved in decreasing the MM of -1,3-glucan. We also found that the C-terminal GPI-anchoring region is important for these functions.

microbiology↗

bioRxiv2021

Histone H3K4me3 and H3K9me3 are super over-methylated in soft tissue sarcoma compared to normal muscle in patient-derived xenograft (PDX) mouse models: an indicator of cancer methionine addiction

Methionine addiction is a fundamental and general hallmark of cancer discovered by us almost a half-century ago [Proc Natl Acad Sci U S A 73 (1976) 1523-1527]. Methionine addiction is defined as the requirement, specific for cancer cells of all types, for exogenous methionine despite the normal ability to synthesize methionine from homocysteine. The methionine addiction of cancer is termed the Hoffman-effect, analogous to the Warburg-effect of the high glucose requirement of cancer cells. Methionine addiction is due to excess transmethylation reactions resulting in high methionine flux in cancer cells, which causes them to selectively arrest under methionine restriction due to depletion of free methionine and S-adenosyl methionine. Recently we have shown methionine-addicted cancer cells over-methylate histone H3 lysine marks which are not over-methylated in normal cells or in low-malignancy methionine-independent revertants derived from methionine-addicted cancer cells. In the present report, we show that in patient-derived xenograft (PDX) mouse models of the most common soft tissue sarcomas: myxofibrosarcoma, undifferentiated pleomorphic sarcoma (UPS) and liposarcoma, histone H3K4me3 and H3K9me3 are super over-methylated compared to normal muscle tissue. This new result is discussed along with our previous reports, regarding the potential of histone H3 over-methylation as a basis of malignancy.

cancer biology↗

bioRxiv2020

Cancer-specific overmethylation of histone H3 lysines is necessary for methionine addiction and malignancy

Methionine addiction is a fundamental and general hallmark of cancer and is an area of current intense interest. Methionine addiction results from the overuse of methionine by cancer cells for excess transmethylation reactions. In order to identify excess transmethylation reactions in cancer and further understand the basis of methionine addiction, we compared the histone H3 lysine-methylation status and malignancy between methionine-addicted cancer cells and their methionine-independent revertants which have regained the ability to grow on low levels of methionine or independently of exogenous methionine. The levels of trimethylated histone H3 lysine marks were reduced in methionine-independent revertants compared to parental cancer cells in vitro. Tumorigenicity and experimental metastatic potential in nude mice were also highly reduced in the methionine-independent revertants compared to the parental cells. Our present results demonstrate that overmethylation of histone H3 lysines is linked with methionine addiction of cancer and to malignancy which suggests a possible causal relationship.

cancer biology↗

bioRxiv2019

The diet and feeding behaviour of the black-and-white colobus (Colobus guereza) in the Kalinzu Forest, Uganda

One of the goals for primate feeding ecology is to understand the factors that affect inter- and intra-specific variations. Therefore, a detailed description of basic feeding ecology in as many populations and sites as possible is necessary and warrants further understanding. The black-and-white colobus (Colobus guereza) or guereza is widely distributed in Africa and is one of the well-studied colobines in terms of their feeding; they demonstrate considerable variation in their diets in response to local conditions. We studied the diet of a group of guerezas in the Kalinzu Forest, Uganda, for over 30 consecutive months using behavioural observation (4,308 h total), phenology, and vegetation surveys. A total of 31 plant species were consumed by the study group. This study group was predominantly folivorous; the majority of their feeding time was involved in feeding on young leaves (87%). However, during certain times of the year, fruits and seeds accounted for 45% of monthly feeding time. Young leaves of Celtis durandii were by far the most important food, which constituted 58% of the total feeding records. There was a significant increase in the consumption of fruits and flowers once young leaf availability was low, but their consumption of fruits did not significantly increase even when fruit availability was high. Their monthly dietary diversity increased as the number of available plants with young leaves declined, suggesting that much of the dietary diversity in the study group may be attributable to the young leaf portion of their diet. Our findings may help contribute to a better understanding of the dietary adaptations and feeding ecology of guerezas in response to local environmental conditions.

ecology↗