The plant root tip is a highly specialized region where cells transition from stem cells to differentiated types and respond to environmental cues. Yet, cell-type-specific proteomic responses to abiotic stress in field-grown plants remain poorly understood. This study generated proteomes for five root-tip cell types in switchgrass (Panicum virgatum), including (1) quiescent center and stem cell niche (Quc), (2) protodermal epidermal cells in the meristematic zone (PEC), (3) epidermal cells in the transition and elongation zones (Epi), (4) peripheral root cap cells (PRC) and (5) columella root cap cells (Col), and characterized their drought-responsive profiles. Root tips from seven-year-old field-grown "Alamo" plants under well-watered or long-term drought conditions were analyzed using laser capture microdissection (LCM) coupled with nanoPOTS and nano-LC-MS. In well-watered samples, 6336-6640 proteins were quantified per cell type, and principal component analysis confirmed distinct proteomic identities. Drought-stressed samples, collected from fewer cells per type, yielded 1109-3298 proteins, with 4,493 proteins quantified overall and 935 shared across all cell types. After median normalization of peptide abundance, differentially abundant proteins (DAPs) were identified using Welch's t test (|log2FC| > 1, adjusted p ≤ 0.05), revealing cell-type-specific drought responses, with the largest numbers of DAPs in Quc and Col cells. DAPs were associated with phytohormone biosynthesis and signaling (auxin, cytokinin, jasmonic acid), DNA repair and mitosis (notably enriched in Quc), and metabolic pathways involving amino acids, carbohydrates, and lipids. Stress-responsive proteins generally increased, whereas proteins linked to translation decreased across all cell types. Overall, this work provides the first spatially resolved, cell-type-specific root-tip proteomes from field-grown switchgrass, offering new insight into distinct cellular strategies underlying drought tolerance.

Understanding the effects of multiple global change drivers, for example, warming (W) and nitrogen (N) fertilization, is critical for accurately predicting ecosystem responses to climate change. This study investigates the main and interactive effects of soil warming and N fertilization on soil organic carbon (SOC), total nitrogen (TN), microbial biomass, extracellular enzyme activities (EEAs), and soil respiration (Rs) in a switchgrass (Panicum virgatum) cropland located in Middle Tennessee. The field experiment employed a split-plot design with two levels of warming (ambient and heated) and two levels of N fertilization (zero and 168 kg N ha-1 year-1). Hourly measurements of Rs, soil temperature (T), and volumetric moisture (Mv), along with biweekly SOC, TN, microbial biomass carbon (MBC) and nitrogen (MBN), and EEAs in soil samples (0-10 cm) were quantified consecutively for 1 year. Warming significantly increased T by 2.92 degrees C, reduced Mv by 32%, and enhanced Rs by 19%, respectively, but significantly reduced nitrogen acquisition enzyme (N acq), acid phosphatase (AP), peroxidase (PER), and oxidase (OX). Relative to unfertilized treatment, N fertilization significantly reduced Rs by 14%. There were no significant main or interactive effects of warming and N fertilization on MBC, MBN, SOC, TN, and C:N. A significant negative interaction of warming and N fertilization on Rs was observed, such that N fertilization suppressed Rs by 24% compared to unfertilized treatments under warming conditions. In addition, a significant negative interaction on PER and a significant positive interaction on AP were observed. These results suggest that warming significantly enhanced soil respiratory C losses, while N fertilization reduced this warming impact, likely through reduced enzyme activity and shifts in microbial community function and resource use. The need for long-term field trials is imperative to elucidate the mechanisms underlying these responses under the combined warming and N fertilization, particularly in bioenergy croplands.

Background: Tomatoes are self-pollinating plants, and successful fruit set depends on the production of functional pollen within the same flower. Our previous studies have shown that the ‘Black Vernissage’ tomato variety exhibits greater resilience to heat stress in terms of pollen productivity compared to the ‘Micro-Tom’ variety. Pollen productivity is determined by meiotic activity during microsporogenesis and the development of free microspores during gametogenesis. This study focused on identifying heat stress (HS)-induced proteomes in pollen mother cells (PMCs) and microspores. Methods: Tomato plants were grown under two temperature conditions: 26 °C (non-heat-treated control) and 37 °C (heat-treated). Homogeneous cell samples of meiotic PMCs (prior to the tetrad stage) and free microspores were collected using laser capture microdissection (LCM). The heat-induced proteomes were identified using tandem mass tag (TMT)–quantitative proteomics analysis. Results: The enrichment of the meiotic cell cycle in PMCs and the pre-mitotic process in free microspores confirmed the correlation between proteome expression and developmental stage. Under HS, PMCs in both tomato varieties were enriched with heat shock proteins (HSPs). However, the ‘Black Vernissage’ variety exhibited a greater diversity of HSP species and a higher level of enrichment compared to the ‘Micro-Tom’ variety. Additionally, several proteins involved in gene expression and protein translation were downregulated in PMCs and microspores of both varieties. In the PMC proteomes, the relative abundance of proteins showed no significant differences between the two varieties under normal conditions, with very few exceptions. However, HS induced significant differential expression both within and between the varieties. More importantly, these heat-induced differentially abundant proteins (DAPs) in PMCs are directly involved in meiotic cell division, including the meiosis-specific protein ASY3 (Solyc01g079080), the cell division protein kinase 2 (Solyc11g070140), COP9 signalosome complex subunit 1 (Solyc01g091650), the kinetochore protein ndc80 (Solyc01g104570), MORC family CW-type zinc finger 3 (Solyc02g084700), and several HSPs that function in protecting the fidelity of the meiotic processes, including the DNAJ chaperone (Solyc04g009770, Solyc05g055160), chaperone protein htpG (Solyc04g081570), and class I and class II HSPs. In the microspores, most of the HS-induced DAPs were consistently observed across both varieties, with only a few proteins showing significant differences between them under heat stress. These HS-induced DAPs include proteases, antioxidant proteins, and proteins related to cell wall remodeling and the generation of pollen exine. Conclusions: HS induced more dynamic proteomic changes in meiotic PMCs compared to microspores, and the inter-varietal differences in the PMC proteomes align with the effects of HS on pollen productivity observed in the two varieties. This research highlights the importance of the cell-type-specific proteomics approach in identifying the molecular mechanisms that are critical for the pollen developmental process under elevated temperature conditions.

Asparagus tea enhances the taste and flavor of processed foods when used as an ingredient during preparation. In this study, asparagus tea ultra-micro powder was incorporated into wheat flour during the mixing process before noodle formation at levels of 5 %, 10 % and 20 %. Flavor analysis using electric nose (E-nose) and gas chromatography-mass spectrometry (GC-MS) revealed clear distinctions among 100 % wheat flour noodle, green asparagus tea ultra-micro powder noodles (GATUPNs) and white asparagus tea ultra-micro powder noodles (WATUPNs). Based on principal component analysis (PCA) of the volatiles using GC-MS, with a threshold of VIP > 1 and P < 0.05, the key flavor components of GATUPNs were 1-octen-3-ol, hexanal, (E)-2-octenal, pyrazine and 3,5-diethyl-2-methyl-(8Cl, 9Cl). In contrast, the key flavor components of WATUPNs were hexanal and (+)-dipentene. The antioxidant capacity of the noodles exhibited a dose-dependent relationship with the ATUP content, with GATUPNs showing the highest antioxidant activity.

Blanching plays important roles in shaping the volatile profile of asparagus tea. In this study, the flavor of blanched and unblanched asparagus teas were studied in detail by electronic nose (E-nose), electronic tongue (Etongue) and gas chromatography-mass spectrometry (GC-MS) coupled with chemometrics methods. Sensory evaluation showed that in blanched asparagus tea, sweet aroma was significant improved, whereas grassy and harsh smell were declined. Linear discriminant analysis (LDA) of the E-nose data showed a clear discrimination between the blanched and unblanched samples. Volatile metabolites analysis showed that blanching treatment generally resulted in a decrease in aldehydes, pyrroles, pyrazines and an increase in ketones and hydrocarbons. Furthermore, styrene, nerylacetone, pentanal, and heptanal were identified as key compounds causing sweet aroma in blanched asparagus teas. While benzothiazole, 2-pentylfuran, naphthalene and several additional compounds are responsible for the green odor in unblanched asparagus teas. The E-tongue and antioxidant activity showed that blanched improved the quality of asparagus tea. These results provided a new insight and scientific basis to improve the processing techniques and quality control for asparagus tea.

Background Goat rumen microbial communities are perceived as one of the most potential biochemical reservoirs of multi-functional enzymes, which are applicable to enhance wide array of bioprocesses such as the hydrolysis of cellulose and hemi-cellulose into fermentable sugar for biofuel and other value-added biochemical production. Even though, the limited understanding of rumen microbial genetic diversity and the absence of effective screening culture methods have impeded the full utilization of these potential enzymes. In this study, we applied culture independent metagenomics sequencing approach to isolate, and identify microbial communities in goat rumen, meanwhile, clone and functionally characterize novel cellulase and xylanase genes in goat rumen bacterial communities. Results Bacterial DNA samples were extracted from goat rumen fluid. Three genomic libraries were sequenced using Illumina HiSeq 2000 for paired-end 100-bp (PE100) and Illumina HiSeq 2500 for paired-end 125-bp (PE125). A total of 435gb raw reads were generated. Taxonomic analysis using Graphlan revealed that Fibrobacter , Prevotella , and Ruminococcus are the most abundant genera of bacteria in goat rumen. SPAdes assembly and prodigal annotation were performed. The contigs were also annotated using the DOE-JGI pipeline. In total, 117,502 CAZymes, comprising endoglucanases, exoglucanases, beta-glucosidases, xylosidases, and xylanases, were detected in all three samples. Two genes with predicted cellulolytic/xylanolytic activities were cloned and expressed in E. coli BL21(DE3). The endoglucanases and xylanase enzymatic activities of the recombinant proteins were confirmed using substrate plate assay and dinitrosalicylic acid (DNS) analysis. The 3D structures of endoglucanase A and endo-1,4-beta xylanase was predicted using the Swiss Model. Based on the 3D structure analysis, the two enzymes isolated from goat’s rumen metagenome are unique with only 56–59% similarities to those homologous proteins in protein data bank (PDB) meanwhile, the structures of the enzymes also displayed greater stability, and higher catalytic activity. Conclusions In summary, this study provided the database resources of bacterial metagenomes from goat’s rumen fluid, including gene sequences with annotated functions and methods for gene isolation and over-expression of cellulolytic enzymes; and a wealth of genes in the metabolic pathways affecting food and nutrition of ruminant animals.

The commercialization of GE crops requires a rigorous safety assessment, which includes a precise DNA level characterization of inserted T-DNA. In the past, several strategies have been developed for identifying T-DNA insertion sites including, Southern blot and different PCR-based methods. However, these methods are often challenging to scale up for screening of dozens of transgenic events and for crops with complex genomes, like potato. Here, we report using target capture sequencing (TCS) to characterize the T-DNA structure and insertion sites of 34 transgenic events in potato. This T-DNA is an 18 kb fragment between left and right borders and carries three resistance (R) genes (RB, Rpi-blb2 and Rpi-vnt1.1 genes) that result in complete resistance to late blight disease. Using TCS, we obtained a high sequence read coverage within the T-DNA and junction regions. We identified the T-DNA breakpoints on either ends for 85% of the transgenic events. About 74% of the transgenic events had their T-DNA with 3R gene sequences intact. The flanking sequences of the T-DNA were from the potato genome for half of the transgenic events, and about a third (11) of the transgenic events have a single T-DNA insertion mapped into the potato genome, of which five events do not interrupt an existing potato gene. The TCS results were confirmed using PCR and Sanger sequencing for 6 of the best transgenic events representing 20% of the transgenic events suitable for regulatory approval. These results demonstrate the wide applicability of TCS for the precise T-DNA insertion characterization in transgenic crops.

Heat stress (HS) poses a significant challenge to tomato production due to disruption of the reproductive organs, especially the male gametophytes. This study reports HS-induced proteome changes in meiotic pollen mother cells during early stages of anther development. Tomato (Solanum lycopersicum L. × S. habrochaites) 'Maxifort' were grown in a heated polytunnel in Nashville, Tennessee, USA. Plants at flowering stage were subjected to heat treatment at 40 ± 2 °C for 4 hr (11:00−15:00 HR); and the non-heat-treated control was at 30 ± 2 °C (day/night) at the same period of time for 10 d. The size of the flower buds containing meiotic pollen mother cells was determined based on the histology of DAPI stained cross section of anthers. Flower buds were embedded in optimal cutting temperature solutions (OCT) and then cut into sections of 20 µm thickness. Sections containing meiotic pollen mother cells were collected using laser capture microdissection (LCM). A protein extraction procedure was optimized for the LCM collected pollen samples which yielded 25−30 μg protein from 150,000−200,000 pollen cells. The heat-induced proteomes of meiotic pollen mother cells were quantified using tandem mass tag (TMT) quantitative proteomics analysis. Among the 6,343 quantified proteins, 254 differentially expressed proteins (DEPs) showed significant differences in abundance level from heat treated to non-heat-treated control conditions. The heat-up-regulated-DEPs (96 proteins) include heat shock proteins, calreticulin and exocytosis (synaptobrevin) which are involved in protein folding/refolding/targeting/removal and secretion of aggregated and damaged proteins/peptides. The heat-down-regulated-DEPs (158 proteins) were involved in pathways of ubiquitin-mediated protein degradation, antioxidant mechanism, and metabolic processes of carbohydrates and lipids. Proteins affecting apoptotic programmed cell death and pollen mother cell meiotic activity were significantly changed under HS. The identified proteins and the affected biological processes could represent the major heat tolerance mechanisms during early developmental stages of male gametophyte when exposed to daily periods of above 40 °C HS condition.

Aluminum (Al) toxicity primarily targets the root tips, inhibiting root growth and function and leading to crop yield losses on acidic soils. Previously we reported using laser capture microdissection (LCM) proteomics to identify Al-induced proteins in the outer layer cells in the transitional zone of tomato root-tips. This study aims to further characterize Al-induced proteomic dynamics from the outer to interior tissues, thus providing a panoramic view reflecting Al resistance in the root tip as a whole in tomatoes. Three types of cells were isolated via LCM from the basal 350-400 mu m (below cell elongation regions) of root tips using tomato (Solanum lycopersicum) 'Micro-Tom' plants. Type I and Type II were from Al-treated plants. Type I included cells of the outer three layers, i.e., the epidermis and cortex initials and the quiescent center (QC) in root apical meristem (RAM), and Type II possessed the interior tissues of the same region. Type III contained cells from the non-Al-treated root tips collected in the same region as Type I. Two tandem mass tag (TMT) proteomics analyses with three biological replicates for each sample type were conducted. The TMTexp1 (comparing Type I and Type II) identified 6575 quantifiable proteins and 178 different abundance proteins (DAPs). The TMTexp2 (comparing Type I and Type III) identified 7197 quantifiable proteins and 162 DAPs. Among all quantified proteins (7685) from the two TMT experiments, 6088 (79%) proteins, including 313 DAPs (92% of the 340 total), were identified in all tissues. A model reflecting the tissue-specific Al-resistance mechanism was proposed, in which the level of the citrate transporter MATE protein, involved in Al exclusion, accumulated to the highest level in the outer-layer cells but decreased toward the interior of root-tips (which concurs with the tissue-specific importance in Al resistance). Proteins for biosynthesis of ethylene and jasmonic acid, proteolytic enzymes, stress-responsive proteins, and cell wall modeling were affected by Al treatment, some in a cell type-specific manner. The KEGG metabolite pathways enriched with these DAPs changed depending on the cell types. This study demonstrated the advantage of using the tissue/cell-specific analysis for identifying proteins and their dynamic changes directly associated with Al resistance in the root-tip region. The proteomics datasets have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository (https://www.ebi.ac.uk/pride/) with the dataset identifier as PXD021994 under project title: Proteomics studies of outer and inner cellular layers of tomato root-tips for Al stress, Project DOI: 10.6019/ PXD021994; and PXD018234 under Project title: Al-induced root proteomics changes in stress-acclimated tomato plant, Project DOI: https://doi.org/10.6019/PXD018234. Significance: This paper presents the method of using laser capture microdissection (LCM) to collect homogenous cell-type specific tissue samples from the outer layers and inner central regions of tomato root-tips. The tandem mass tag-proteomics analysis showed that the outer-layer cells expressed proteomes that were different from the inner tissues of Al-treated root-tips; proteins related to resistance/tolerance to Al toxicity were highly accumulated in the outer-layer cells. Furthermore, the Al-treated outer-layer cells expressed proteomes which were different from the non-Al treated counterpart cells. This study has provided the first dataset of proteins differentiating from the outer to inner layers of cells in Al-treated root-tips. It provided convincing experimental evidences demonstrating the single-cell type proteomics as a powerful analytical approach to identify Al tolerance mechanisms in plants. The analytical procedure of LCM-tandem mass tag-quantitative proteomics analysis has a broad application for proteomics analysis of spatially separated cells in complex tissues.

The hard-end is a disorder of pear fruit, however, the mechanisms underlying its development remain unknown. In this study, we found that the hard-end fruit contained a higher transcript abundance level of ethylene-response factor 1b-like (PpERF1b-like) and released more ethylene compared to normal pear. In the ethephon treated normal fruit, flesh tissues accumulated more lignin together with elevated expression of PpERF1b-like. Overexpressing PpERF1b-like transiently in fruit and stably in callus increased lignin accumulation and the expression of lignin biosynthesis genes; the opposite results were observed in fruit showing repressed expression of PpERF1b-like. These results confirmed the role of PpERF1b-like in promoting hard-end formation through promoting lignin synthesis. This study provided valuable information for further clarifying the regulation of hard-end formation in pear.

In the U.S., 30-40% of all food produced ends up as waste. By taking advantage of biological processes this waste nutrients can be converted into value-added 2,3-butanediol( 2,3-BDO). However, food waste contains live bacteria and fungi which must first be inactivated, a process typically done with autoclaving under high pressure steam. If contaminantsare not removed they can out-compete added industrial microbes for nutrients, resultingin lower yields of bio-products. Unfortunately, sterilization methods such as autoclavinggreatly increase production time, and increase energy consumption. This creates a demandfor novel microorganisms that can out-compete food waste microbiota by natural means without the need for sterilization of food waste. For this study, several Bacillus licheniformis isolates from Yellowstone National Park were investigated for their potential use in the 2,3-BDO industry. B. licheniformis species are a strain of industrial importance as of late, due to the wide metabolic functions and sustainable growth conditions above 45 degrees C. Whole genomic sequencing data and biochemical classification of B. licheniformis YNP1-TSU, B. licheniformis YNP2TSU, and B. licheniformis YNP3-TSU were assessed and revealed a wide assortment of antimicrobial peptides and antibodies as well as catabolic genes for assimilation of glucose, fructose, galactose, xylose, arabinose, mannose, starch and sucrose, and linoleic acid. All three B. licheniformis strains had an optimal growth temperature of 50 degrees C, and were identified as high 2,3-BDO producers. Each strain YNP1-TSU, YNP2-TSU, and YNP3-TSU yielded 0.44 g/g, 0.45 g/g, and 0.43 g/g from mixed sugars found in non-sterilized food waste, respectively. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Background Bacillus cereus is a bacterial species which grows efficiently on a wide range of carbon sources and accumulates biopolymer poly-hydroxybutyrate (PHB) up to 80% cell dry weight. PHB is an aliphatic polymer produced and stored intracellularly as a reservoir of carbon and energy, its mobilization is a key biological process for sporulation in Bacillus spp. Previously, B. cereus tsu1 was isolated and cultured on rapeseed cake substrate (RCS), with maximum of PHB accumulation reached within 12 h, and depleted after 48 h. Fore-spore and spore structure were observed after 24 h culture. Results Quantitative proteomic analysis of B. cereus tsu1 identified 2952 quantifiable proteins, and 244 significantly changed proteins (SCPs) in the 24 h:12 h pair of samples, and 325 SCPs in the 48 h:12 h pair of samples. Based on gene ontology classification analysis, biological processes enriched only in the 24 h:12 h SCPs include purine nucleotide metabolism, protein folding, metal ion homeostasis, response to stress, carboxylic acid catabolism, and cellular amino acid catabolism. The 48 h:12 h SCPs were enriched into processes including carbohydrate metabolism, protein metabolism, oxidative phosphorylation, and formation of translation ternary structure. A key enzyme for PHB metabolism, poly(R)-hydroxyalkanoic acid synthase (PhaC, KGT44865) accumulated significantly higher in 12 h-culture. Sporulation related proteins SigF and SpoEII were significantly higher in 24 h-samples. Enzymes for nitrate respiration and fermentation accumulated to the highest abundance level in 48 h-culture. Conclusions Changes in proteome of B. cereus tsu1 during PHB intracellular mobilization were characterized in this study. The key enzyme PhaC for PHB synthesis increased significantly after 12 h-culture which supports the highest PHB accumulation at this time point. The protein abundance level of SpoIIE and SigF also increased, correlating with sporulation in 24 h-culture. Enzymes for nitrate respiration and fermentation were significantly induced in 48 h-culture which indicates the depletion of oxygen at this stage and carbon flow towards fermentative growth. Results from this study provide insights into proteome profile changes during PHB accumulation and reuse, which can be applied to achieve a higher PHB yield and to improve bacterial growth performance and stress resistance.

Switchgrass plants were grown in a Sandwich tube system to induce gradual drought stress by withholding watering. After 29 days, the leaf photosynthetic rate decreased significantly, compared to the control plants which were watered regularly. The drought-treated plants recovered to the same leaf water content after three days of re-watering. The root tip (1cm basal fragment, designated as RT1 hereafter) and the elongation/maturation zone (the next upper 1 cm tissue, designated as RT2 hereafter) tissues were collected at the 29th day of drought stress treatment, (named SDT for severe drought treated), after one (D1W) and three days (D3W) of re-watering. The tandem mass tags mass spectrometry-based quantitative proteomics analysis was performed to identify the proteomes, and drought-induced differentially accumulated proteins (DAPs). From RT1 tissues, 6156, 7687, and 7699 proteins were quantified, and 296, 535, and 384 DAPs were identified in the SDT, D1W, and D3W samples, respectively. From RT2 tissues, 7382, 7255, and 6883 proteins were quantified, and 393, 587, and 321 proteins DAPs were identified in the SDT, D1W, and D3W samples. Between RT1 and RT2 tissues, very few DAPs overlapped at SDT, but the number of such proteins increased during the recovery phase. A large number of hydrophilic proteins and stress-responsive proteins were induced during SDT and remained at a higher level during the recovery stages. A large number of DAPs in RT1 tissues maintained the same expression pattern throughout drought treatment and the recovery phases. The DAPs in RT1 tissues were classified in cell proliferation, mitotic cell division, and chromatin modification, and those in RT2 were placed in cell wall remodeling and cell expansion processes. This study provided information pertaining to root zone-specific proteome changes during drought and recover phases, which will allow us to select proteins (genes) as better defined targets for developing drought tolerant plants. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD017441.

This paper reports a laser capture microdissection-tandem mass tag-quantitative proteomics analysis of Al-sensitive cells in root tips. Cherry tomato (Solarium lycopersicum var. cerasiforme 'LA2710') seedlings were treated under 15 mu M Al3+ activity for 13 d. Root-tip longitudinal fresh frozen tissue sections of 10 mu m thickness were prepared. The Al-sensitive root zone and cells were determined using histochemical analysis of root-tips and micro-sections. A procedure for collecting the Al-sensitive cells using laser capture microdissection-protein extraction-tandem mass tag-proteomics analysis was developed. Proteomics analysis of 18 mu g protein/sample with three biological replicates per treatment condition identified 3879 quantifiable proteins each associated with two or more unique peptides. Quantified proteins constituted a broad range of Kyoto Encyclopedia of Genes and Genomes pathways when searched in the annotated tomato genome. Differentially expressed proteins between the Al-treated and non-Al treated control conditions were identified, including 128 Al-up-regulated and 32 Al-down-regulated proteins. Analysis of functional pathways and protein-protein interaction networks showed that the Al-down-regulated proteins are involved in transcription and translation, and the Al-up-regulated proteins are associated with antioxidant and detoxification and protein quality control processes. The proteomics data are available via ProteomeXchange with identifier PXD010459 under project title 'LCM-quantitative proteomics analysis of Al-sensitive tomato root cells'. Significance: This paper presents an efficient laser capture microdissection-tandem mass tag-quantitative proteomics analysis platform for the analysis of Al sensitive root cells. The analytical procedure has a broad application for proteomics analysis of spatially separated cells from complex tissues. This study has provided a comprehensive proteomics dataset expressed in the epidermal and outer-cortical cells at root-tip transition zone of Al-treated tomato seedlings. The proteomes from the Al-sensitive root cells are valuable resources for understanding and improving Al tolerance in plants.

2,3-Butanediol (2,3-BD) is an important platform chemical that can be produced biologically. It is currently fermented below 40 degrees C using mesophilic strains at acid to neutral pH conditions, but the processes often suffer bacterial contamination. Here we reported a new nonpathogenic strain Bacillus licheniformis YNP5-TSU isolated from Yellowstone National Park, which produces 2,3-BD with high yield and productivity at thermophilic and alkaline conditions. B. licheniformis YNPS-TSU has the ability to survive in pH ranges from 8.0 to 10.0 and temperature ranges from 40 to 55 degrees C, which greatly reduces the chance of contamination from other microorganisms. At its optimum condition with a temperature of 50 degrees C and pH of 8-9, YNPS-TSU can produce 27.4 g/L 2,3-BD from 60 g/L glucose, with a high yield of 0.46 g/g (92% of theoretical value) and productivity of 1.1 g/L/h in a batch fermentation. YNPS-TSU also can ferment different carbohydrates including fructose, sucrose, arabinose, galactose, mannose, xylose, as well as alcohols such as glycerol. The effects of nitrogen and mineral sources on 2,3-BD fermentation were also investigated to improve the fermentation process. In a fed-batch fermentation, 99.3 g/L of 2,3-BD was obtained within 96 h, with a yield of 0.41 g/g. The results provided indicate that B. licheniformis YNP5-TSU is a very adaptable strain to withstand harsh environments while still producing 2,3-BD near theoretical values.

Conversion of food waste into 2,3-butanediol (2,3-BDO) via microbial fermentation provides a promising way to reduce waste disposal to landfills and produce sustainable chemicals. However, sterilization of food waste, an energy- and capital-costly process, is generally required before fermentation to avoid any contamination, which reduces the energy net output and economic feasibility of food waste fermentation. In this study, we investigated the non-sterile fermentation of food waste to produce 2,3-BDO using a newly isolated thermophilic and alkaliphilic B. licheniformis YNP5-TSU. Three unitary food waste samples (i.e., pepper, pineapple, cabbage wastes) and one miscellaneous food waste mixture were respectively inoculated with B. licheniformis YNP5-TSU under non-sterile conditions. At 50 °C and an initial pH of 9.0, B. licheniformis YNP5-TSU was able to consume all sugars in food waste and produce 5.2, 5.9, 5.9 and 4.3 g/L of 2,3-BDO within 24 h from pepper, pineapple, cabbage and miscellaneous wastes, respectively, corresponding to a yield of 0.40, 0.38, 0.41 and 0.41 g 2,3-BDO/g sugar. These 2,3-BDO concentrations and yields from the non-sterile fermentations were comparable to those from the traditional sterile fermentations, which produced 4.0-6.8 g/L of 2,3-BDO with yields of 0.31-0.48 g 2,3-BDO/g sugar. Moreover, B. licheniformis was able to ferment various food wastes (pepper, pineapple and miscellaneous wastes) without any external nutrient addition and produce similar 2,3-BDO quantities. The non-sterile fermentation of food waste using novel thermophilic and alkaliphilic B. licheniformis YNP5-TSU provides a robust and energy-efficient approach to convert food waste to high-value chemicals.