Tomato domestication rather than subsequent breeding events reduces microbial associations related to phosphorus recovery.

Legacy phosphorus (P) is a reservoir of sparingly available P, and its recovery could enhance sustainable use of nonrenewable mineral fertilizers. Domestication has affected P acquisition, but it is unknown if subsequent breeding efforts, like the Green Revolution (GR), had a similar effect. We examined how domestication and breeding events altered P acquisition by growing wild, traditional (pre-GR), and modern (post-GR) tomato in soil with legacy P but low bioavailable P. Wild tomatoes, particularly accession LA0716 (Solanum pennellii), heavily cultured rhizosphere P solubilizers, suggesting reliance on microbial associations to acquire P. Wild tomato also had a greater abundance of other putatively beneficial bacteria, including those that produce chelating agents and antibiotic compounds. Although wild tomatoes had a high abundance of these P solubilizers, they had lower relative biomass and greater P stress factor than traditional or modern tomato. Compared to wild tomato, domesticated tomato was more tolerant to P deficiency, and both cultivated groups had a similar rhizosphere bacterial community composition. Ultimately, this study suggests that while domestication changed tomato P recovery by reducing microbial associations, subsequent breeding processes have not further impacted microbial P acquisition mechanisms. Selecting microbial P-related traits that diminished with domestication may therefore increase legacy P solubilization.

Harnessing Phosphorous (P) Fertilizer-Insensitive Bacteria to Enhance Rhizosphere P Bioavailability in Legumes.

Phosphorous (P) is widely used in agriculture; yet, P fertilizers are a nonrenewable resource. Thus, mechanisms to improve soil P bioavailability need to be found. Legumes are efficient in P acquisition and, therefore, could be used to develop new technologies to improve soil P bioavailability. Here, we studied different species and varieties of legumes and their rhizosphere microbiome responses to low-P stress. Some varieties of common beans, cowpeas, and peas displayed a similar biomass with and without P fertilization. The rhizosphere microbiome of those varieties grown without P was composed of unique microbes displaying different levels of P solubilization and mineralization. When those varieties were amended with P, some of the microbes involved in P solubilization and mineralization decreased in abundance, but other microbes were insensitive to P fertilization. The microbes that decreased in abundance upon P fertilization belonged to groups that are commonly used as biofertilizers such as Pseudomonas and Azospirillum. The microbes that were not affected by P fertilization constitute unique species involved in P mineralization such as Arenimonas daejeonensis, Hyphomicrobium hollandicum, Paenibacillus oenotherae, and Microlunatus speluncae. These P-insensitive microbes could be used to optimize P utilization and drive future sustainable agricultural practices to reduce human dependency on a nonrenewable resource.

Shifts of the soil microbiome composition induced by plant-plant interactions under increasing cover crop densities and diversities.

Interspecific and intraspecific competition and facilitation have been a focus of study in plant-plant interactions, but their influence on plant recruitment of soil microbes is unknown. In this greenhouse microcosm experiment, three cover crops (alfalfa, brassica, and fescue) were grown alone, in paired mixtures, and all together under different densities. For all monoculture trials, total pot biomass increased as density increased. Monoculture plantings of brassica were associated with the bacteria Azospirillum spp., fescue with Ensifer adhaerens, and alfalfa with both bacterial taxa. In the polycultures of cover crops, for all plant mixtures, total above-ground alfalfa biomass increased with density, and total above ground brassica biomass remained unchanged. For each plant mixture, differential abundances highlighted bacterial taxa which had not been previously identified in monocultures. For instance, mixtures of all three plants showed an increase in abundance of Planctomyces sp. SH-PL14 and Sandaracinus amylolyticus which were not represented in the monocultures. Facilitation was best supported for the alfalfa-fescue interaction as the total above ground biomass was the highest of any mixture. Additionally, the bulk soil microbiome that correlated with increasing plant densities showed increases in plant growth-promoting rhizobacteria such as Achromobacter xylosoxidans, Stentotrophomonas spp., and Azospirillum sp. In contrast, Agrobacterium tumefaciens, a previously known generalist phytopathogen, also increased with alfalfa-fescue plant densities. This could suggest a strategy by which, after facilitation, a plant neighbor could culture a pathogen that could be more detrimental to the other.

Community structure and abundance of ACC deaminase containing bacteria in soils with 16S-PICRUSt2 inference or direct acdS gene sequencing.

Bacteria containing the enzyme 1-aminocyclopropane-1-carboxylate deaminase (ACCD+) can reduce plant ethylene levels and increase root development and elongation resulting in increased resiliency to drought and other plant stressors. Although these bacteria are ubiquitous in the soil, non-culture-based methods for their enumeration and identification are not well developed. In this study we compare two culture-independent approaches for identifying ACCD+ bacteria. First, quantitative PCR (qPCR) and direct acdS sequencing with newly designed gene-specific primers; and second, phylogenetic construction of 16S rRNA amplicon libraries with the PICRUSt2 tool. Using soils from eastern Colorado, we showed complementary yet differing results in ACCD+ abundance and community structure responding to water availability. Across all sites, gene abundances estimated from qPCR with the acdS gene-specific primers and phylogenetic reconstruction using PICRUSt2 were significantly correlated. However, PICRUSt2 identified members of the Acidobacteria, Proteobacteria, and Bacteroidetes phyla (now known as Acidobacteriota, Pseudomonadota, and Bacteroidota according to the International Code of Nomenclature of Prokaryotes) as ACCD+ bacteria, whereas the acdS primers amplified only members of the Proteobacteria phyla. Despite these differences, both measures showed that bacterial abundance of ACCD+ decreased as soil water content decreased along a potential evapotranspiration (PET) gradient at three sites in eastern Colorado. One major advantage of using 16S sequencing and PICRUSt2 in metagenomic studies is the ability to get a potential functional profile of all known KEGG (Kyoto Encyclopedia of Genes and Genomes) enzymes within the bacterial community of a single soil sample. The 16S-PICRUSt2 method paints a broader picture of the biological and biochemical function of the soil microbiome compared to direct acdS sequencing; however, phylogenetic analysis based on 16S gene relatedness may not reflect that of the functional gene of interest.

A Microbiological Approach to Alleviate Soil Replant Syndrome in Peaches.

Replant syndrome (RS) is a global problem characterized by reduced growth, production life, and yields of tree fruit/nut orchards. RS etiology is unclear, but repeated monoculture plantings are thought to develop a pathogenic soil microbiome. This study aimed to evaluate a biological approach that could reduce RS in peach (Prunus persica) orchards by developing a healthy soil bacteriome. Soil disinfection via autoclave followed by cover cropping and cover crop incorporation was found to distinctly alter the peach soil bacteriome but did not affect the RS etiology of RS-susceptible 'Lovell' peach seedlings. In contrast, non-autoclaved soil followed by cover cropping and incorporation altered the soil bacteriome to a lesser degree than autoclaving but induced significant peach growth. Non-autoclaved and autoclaved soil bacteriomes were compared to highlight bacterial taxa promoted by soil disinfection prior to growing peaches. Differential abundance shows a loss of potentially beneficial bacteria due to soil disinfection. The treatment with the highest peach biomass was non-autoclaved soil with a cover crop history of alfalfa, corn, and tomato. Beneficial bacterial species that were cultivated exclusively in the peach rhizosphere of non-autoclaved soils with a cover crop history were Paenibacillus castaneae and Bellilinea caldifistulae. In summary, the non-autoclaved soils show continuous enhancement of beneficial bacteria at each cropping phase, culminating in an enriched rhizosphere which may help alleviate RS in peaches.

Comparison of Oxford Nanopore Technologies and Illumina MiSeq sequencing with mock communities and agricultural soil.

Illumina MiSeq is the current standard for characterizing microbial communities in soil. The newer alternative, Oxford Nanopore Technologies MinION sequencer, is quickly gaining popularity because of the low initial cost and longer sequence reads. However, the accuracy of MinION, per base, is much lower than MiSeq (95% versus 99.9%). The effects of this difference in base-calling accuracy on taxonomic and diversity estimates remains unclear. We compared the effects of platform, primers, and bioinformatics on mock community and agricultural soil samples using short MiSeq, and short and full-length MinION 16S rRNA amplicon sequencing. For all three methods, we found that taxonomic assignments of the mock community at both the genus and species level matched expectations with minimal deviation (genus: 80.9-90.5%; species: 70.9-85.2% Bray-Curtis similarity); however, the short MiSeq with error correction (DADA2) resulted in the correct estimate of mock community species richness and much lower alpha diversity for soils. Several filtering strategies were tested to improve these estimates with varying results. The sequencing platform also had a significant influence on the relative abundances of taxa with MiSeq resulting in significantly higher abundances Actinobacteria, Chloroflexi, and Gemmatimonadetes and lower abundances of Acidobacteria, Bacteroides, Firmicutes, Proteobacteria, and Verrucomicrobia compared to the MinION platform. When comparing agricultural soils from two different sites (Fort Collins, CO and Pendleton, OR), methods varied in the taxa identified as significantly different between sites. At all taxonomic levels, the full-length MinION method had the highest similarity to the short MiSeq method with DADA2 correction with 73.2%, 69.3%, 74.1%, 79.3%, 79.4%, and 82.28% of the taxa at the phyla, class, order, family, genus, and species levels, respectively, showing similar patterns in differences between the sites. In summary, although both platforms appear suitable for 16S rRNA microbial community composition, biases for different taxa may make the comparison between studies problematic; and even with a single study (i.e., comparing sites or treatments), the sequencing platform can influence the differentially abundant taxa identified.

Root exudate-derived compounds stimulate the phosphorus solubilizing ability of bacteria.

Low phosphorus (P) availability in soils is a major challenge for sustainable food production, as most soil P is often unavailable for plant uptake and effective strategies to access this P are limited. Certain soil occurring bacteria and root exudate-derived compounds that release P are in combination promising tools to develop applications that increase phosphorus use efficiency in crops. Here, we studied the ability of root exudate compounds (galactinol, threonine, and 4-hydroxybutyric acid) induced under low P conditions to stimulate the ability of bacteria to solubilize P. Galactinol, threonine, and 4-hydroxybutyric acid were incubated with the P solubilizing bacterial strains Enterobacter cloacae, Pseudomonas pseudoalcaligenes, and Bacillus thuringiensis under either inorganic (calcium phosphate) or organic (phytin) forms of plant-unavailable P. Overall, we found that the addition of individual root exudate compounds did not support bacterial growth rates. However, root exudates supplemented to the different bacterial appeared to enhance P solubilizing activity and overall P availability. Threonine and 4-hydroxybutyric acid induced P solubilization in all three bacterial strains. Subsequent exogenous application of threonine to soils improved the root growth of corn, enhanced nitrogen and P concentrations in roots and increased available levels of potassium, calcium and magnesium in soils. Thus, it appears that threonine might promote the bacterial solubilization and plant-uptake of a variety of nutrients. Altogether, these findings expand on the function of exuded specialized compounds and propose alternative approaches to unlock existing phosphorus reservoirs of P in crop lands.

CaRPE: the Carbon Reduction Potential Evaluation tool for building climate mitigation scenarios on US agricultural lands.

The Carbon Reduction Potential Evaluation (CaRPE) tool is a web-based interactive tool that integrates two databases for the USA collected at county/multi-county scales to visualize and estimate the climate benefits of implementing a variety of conservation practices on croplands and grazing lands. The COMET-Planner tool provides county/multi-county carbon sequestration and greenhouse gas emission reduction coefficients associated with the adoption of climate-smart agricultural management practices. The CaRPE tool couples these coefficients, reported in tonnes of carbon dioxide equivalents (CO2e) per acre per year, with county-level cropland and grazing land acres extracted from the US Agricultural Census. The CaRPE graphical user interface allows users to quickly and easily build and export scenarios of new conservation practice adoption on desired acreages and locations at state, regional or national scales. Results are in tonnes CO2e per year, and each scenario can be exported in tabular and map formats at the selected scales. Existing county-level cropland acreage data provide the upper boundaries for acres of adoption and can be modified based on specific goals established by the user.The output may be used to develop potential targets of adoption and help inform decisions related to resource prioritization and planning efforts. In collaboration with local experts and farmer-led organizations, the results can provide a key starting block to prioritize practices and areas that contribute to climate benefits. As the underlying databases and models are updated and improved, CaRPE can be revised accordingly to increase accuracy and enhance applicability. The CaRPE tool and the user guide are available at: Database URL: https://carpe.shinyapps.io/CarpeTool/.

Soil microbiome disruption reveals specific and general plant-bacterial relationships in three agroecosystem soils.

Soil microbiome disruption methods are regularly used to reduce populations of microbial pathogens, often resulting in increased crop growth. However, little is known about the effect of soil microbiome disruption on non-pathogenic members of the soil microbiome. Here, we applied soil microbiome disruption in the form of moist-heat sterilization (autoclaving) to reduce populations of naturally occurring soil microbiota. The disruption was applied to analyze bacterial community rearrangement mediated by four crops (corn, beet, lettuce, and tomato) grown in three historically distinct agroecosystem soils (conventional, organic, and diseased). Applying the soil disruption enhanced plant influence on rhizosphere bacterial colonization, and significantly different bacterial communities were detected between the tested crops. Furthermore, bacterial genera showed significant abundance increases in ways both unique-to and shared-by each tested crop. As an example, corn uniquely promoted abundances of Pseudomonas and Sporocytophaga, regardless of the disrupted soil in which it was grown. Whereas the promotion of Bosea, Dyadobacter and Luteoliobacter was shared by all four crops when grown in disrupted soils. In summary, soil disruption followed by crop introduction amplified the plant colonization of potential beneficial bacterial genera in the rhizosphere.

Conditioned soils reveal plant-selected microbial communities that impact plant drought response.

Rhizobacterial communities can contribute to plant trait expression and performance, including plant tolerance against abiotic stresses such as drought. The conditioning of microbial communities related to disease resistance over generations has been shown to develop suppressive soils which aid in plant defense responses. Here, we applied this concept for the development of drought resistant soils. We hypothesized that soils conditioned under severe drought stress and tomato cultivation over two generations, will allow for plant selection of rhizobacterial communities that provide plants with improved drought resistant traits. Surprisingly, the plants treated with a drought-conditioned microbial inoculant showed significantly decreased plant biomass in two generations of growth. Microbial community composition was significantly different between the inoculated and control soils within each generation (i.e., microbial history effect) and for the inoculated soils between generations (i.e., conditioning effect). These findings indicate a substantial effect of conditioning soils on the abiotic stress response and microbial recruitment of tomato plants undergoing drought stress.

Differential Effects of Phosphorus Fertilization on Plant Uptake and Rhizosphere Microbiome of Cultivated and Non-cultivated Potatoes.

There is evidence that shows that phosphorus (P) fertilization has a moderate effect on the rhizosphere microbial composition of cultivated crops. But how this effect is manifested on wild species of the same crop is not clear. This study compares the impact of phosphorus fertilization with rhizosphere bacterial community composition and its predicted functions, related to P-cycling genes, in both cultivated and non-cultivated potato (Solanum sp.) plants. It was found that the biomass of non-cultivated potatoes was more responsive to P fertilization as compared with cultivated plants. Differences in general bacterial community composition patterns under increasing P amendments were subtle for both potato groups. However, potato genotype significantly influenced community composition with several bacterial families being more abundant in the cultivated plants. In addition, the predicted phosphatases had lower abundances in modern cultivars compared with non-cultivated potatoes. In summary, despite higher accumulation of differentially abundant bacteria in the rhizosphere of cultivated plants, the responsiveness of these plants to increase P levels was lower than in non-cultivated plants.

The Effect of Hops (Humulus lupulus L.) Extract Supplementation on Weight Gain, Adiposity and Intestinal Function in Ovariectomized Mice.

Estrogen decline during menopause is associated with altered metabolism, weight gain and increased risk of cardiometabolic diseases. The gut microbiota also plays a role in the development of cardiometabolic dysfunction and is also subject to changes associated with age-related hormone changes. Phytoestrogens are plant-based estrogen mimics that have gained popularity as dietary supplements for the treatment or prevention of menopause-related symptoms. These compounds have the potential to both modulate and be metabolized by the gut microbiota. Hops (Humulus lupulus L.) contain potent phytoestrogen precursors, which rely on microbial biotransformation in the gut to estrogenic forms. We supplemented ovariectomized (OVX) or sham-operated (SHAM) C57BL/6 mice, with oral estradiol (E2), a flavonoid-rich extract from hops, or a placebo carrier oil, to observe effects on adiposity, inflammation, and gut bacteria composition. Hops extract (HE) and E2 protected against increased visceral adiposity and liver triglyceride accumulation in OVX animals. Surprisingly, we found no evidence of OVX having a significant impact on the overall gut bacterial community structure. We did find differences in the abundance of Akkermansia muciniphila, which was lower with HE treatment in the SHAM group relative to OVX E2 treatment and to placebo in the SHAM group.

A novel approach to determine generalist nematophagous microbes reveals Mortierella globalpina as a new biocontrol agent against Meloidogyne spp. nematodes.

Root-knot nematodes (RKN) such as Meloidogyne spp. are among the most detrimental pests in agriculture affecting several crops. New methodologies to manage RKN are needed such as efficient discovery of nematophagous microbes. In this study, we developed an in vitro high-throughput method relying on the free-living nematode Caenorhabditis elegans and the infection of those nematodes with a soil slurry containing a microbiome likely to house nematophagous microbes. Nematodes were monitored for presence of infection and sub-cultured repeatedly for the purpose of isolating pure cultures of the microbe responsible for conferring the nematicidal activity. Once soil microbes were confirmed to be antagonistic to C. elegans, they were tested for pathogenicity against Meloidogyne chitwoodi. Using this methodology, the fungal isolate Mortierella globalpina was confirmed to be pathogenic in vitro against M. chitwoodi by nematode trapping via hyphal adhesion to the cuticle layer, penetration of the cuticle layer, and subsequently digestion of its cellular contents. M. globalpina was also observed to reduce disease symptomology of RKNs in vivo via significant reduction of root-galls on tomato (Solanum lycopersicum var. Rutgers).

PHAGE Study: Effects of Supplemental Bacteriophage Intake on Inflammation and Gut Microbiota in Healthy Adults.

The gut microbiota is increasingly recognized as an important modulator of human health. As such, there is a growing need to identify effective means of selectively modifying gut microbial communities. Bacteriophages, which were briefly utilized as clinical antimicrobials in the early 20th century, present an opportunity to selectively reduce populations of undesirable microorganisms. However, whether intentional consumption of specific bacteriophages affects overall gut ecology is not yet known. Using a commercial cocktail of Escherichia coli-targeting bacteriophages, we examined their effects on gut microbiota and markers of intestinal and systemic inflammation in a healthy human population. In a double-blinded, placebo-controlled crossover trial, normal to overweight adults consumed bacteriophages for 28 days. Stool and blood samples were collected and used to examine inflammatory markers, lipid metabolism, and gut microbiota. Reductions in fecal E. coli loads were observed with phage consumption. However, there were no significant changes to alpha and beta diversity parameters, suggesting that consumed phages did not globally disrupt the microbiota. However, specific populations were altered in response to treatment, including increases in members of the butyrate-producing genera Eubacterium and a decreased proportion of taxa most closely related to Clostridium perfringens. Short-chain fatty acid production, inflammatory markers, and lipid metabolism were largely unaltered, but there was a small but significant decrease in circulating interleukin-4 (Il-4). Together, these data demonstrate the potential of bacteriophages to selectively reduce target organisms without global disruption of the gut community.

Impact of Edible Cricket Consumption on Gut Microbiota in Healthy Adults, a Double-blind, Randomized Crossover Trial.

Edible insects are often considered a nutritious, protein-rich, environmentally sustainable alternative to traditional livestock with growing popularity among North American consumers. While the nutrient composition of several insects is characterized, all potential health impacts have not been evaluated. In addition to high protein levels, crickets contain chitin and other fibers that may influence gut health. In this study, we evaluated the effects of consuming 25 grams/day whole cricket powder on gut microbiota composition, while assessing safety and tolerability. Twenty healthy adults participated in this six-week, double-blind, crossover dietary intervention. Participants were randomized into two study arms and consumed either cricket-containing or control breakfast foods for 14 days, followed by a washout period and assignment to the opposite treatment. Blood and stool samples were collected at baseline and after each treatment period to assess liver function and microbiota changes. Results demonstrate cricket consumption is tolerable and non-toxic at the studied dose. Cricket powder supported growth of the probiotic bacterium, Bifidobacterium animalis, which increased 5.7-fold. Cricket consumption was also associated with reduced plasma TNF-α. These data suggest that eating crickets may improve gut health and reduce systemic inflammation; however, more research is needed to understand these effects and underlying mechanisms.

Bacterial Microbiome and Nematode Occurrence in Different Potato Agricultural Soils.

Pratylenchus neglectus and Meloidogyne chitwoodi are the main plant-parasitic nematodes in potato crops of the San Luis Valley, Colorado. Bacterial microbiome (16S rRNA copies per gram of soil) and nematode communities (nematodes per 200 g of soil) from five different potato farms were analyzed to determine negative and positive correlations between any bacterial genus and P. neglectus and M. chitwoodi. Farms showed differences in bacterial communities, percentage of bacterivorous and fungivorous nematodes, and numbers of P. neglectus and M. chitwoodi. The farm with the lowest population of P. neglectus and M. chitwoodi had higher abundances of the bacterial genera Bacillus spp., Arthrobacter spp., and Lysobacter spp., and the soil nematode community was composed of more than 30% of fungivorous nematodes. In contrast, the farm with higher numbers of P. neglectus and M. chitwoodi had a lower abundance of the abovementioned bacterial genera, higher abundance of Burkholderia spp., and less than 25% of fungivorous nematodes. The α-Proteobacteria Rhodoplanes, Phenylobacterium, and Kaistobacter positively correlated with M. chitwoodi, and the Bacteroidia and γ-Proteobacteria positively correlated with P. neglectus. Our results, based largely on co-occurrence analyses, suggest that the abundance of Bacillus spp., Arthrobacter spp., and Lysobacter spp. in Colorado potato soils is negatively correlated with P. neglectus and M. chitwoodi abundance. Further studies will isolate and identify bacterial strains of these genera, and evaluate their nematode-antagonistic activity.

myPhyloDB: a local web server for the storage and analysis of metagenomic data.

myPhyloDB v.1.1.2 is a user-friendly personal database with a browser-interface designed to facilitate the storage, processing, analysis, and distribution of microbial community populations (e.g. 16S metagenomics data). MyPhyloDB archives raw sequencing files, and allows for easy selection of project(s)/sample(s) of any combination from all available data in the database. The data processing capabilities of myPhyloDB are also flexible enough to allow the upload and storage of pre-processed data, or use the built-in Mothur pipeline to automate the processing of raw sequencing data. myPhyloDB provides several analytical (e.g. analysis of covariance,t-tests, linear regression, differential abundance (DESeq2), and principal coordinates analysis (PCoA)) and normalization (rarefaction, DESeq2, and proportion) tools for the comparative analysis of taxonomic abundance, species richness and species diversity for projects of various types (e.g. human-associated, human gut microbiome, air, soil, and water) for any taxonomic level(s) desired. Finally, since myPhyloDB is a local web-server, users can quickly distribute data between colleagues and end-users by simply granting others access to their personal myPhyloDB database. myPhyloDB is available athttp://www.ars.usda.gov/services/software/download.htm?softwareid=472 and more information along with tutorials can be found on our websitehttp://www.myphylodb.org. Database URL:http://www.myphylodb.org.

Estimating beta diversity for under-sampled communities using the variably weighted Odum dissimilarity index and OTUshuff.

MOTIVATION: In profiling the composition and structure of complex microbial communities via high throughput amplicon sequencing, a very low proportion of community members are typically sampled. As a result of this incomplete sampling, estimates of dissimilarity between communities are often inflated, an issue we term pseudo ß-diversity. RESULTS: We present a set of tools to identify and correct for the presence of pseudo ß-diversity in contrasts between microbial communities. The variably weighted Odum dissimilarity (DwOdum) allows for down-weighting the influence of either abundant or rare taxa in calculating a measure of similarity between two communities. We show that down-weighting the influence of rare taxa can be used to minimize pseudo ß-diversity arising from incomplete sampling. Down-weighting the influence of abundant taxa can increase the sensitivity of hypothesis testing. OTUshuff is an associated test for identifying the presence of pseudo ß-diversity in pairwise community contrasts. AVAILABILITY AND IMPLEMENTATION: A Perl script for calculating the DwOdum score from a taxon abundance table and performing pairwise contrasts with OTUshuff can be obtained at http://www.ars.usda.gov/services/software/software.htm?modecode=30-12-10-00. CONTACT: daniel.manter@ars.usda.gov SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Pre-treatment step with Leuconostoc mesenteroides or L. pseudomesenteroides strains removes furfural from Zymomonas mobilis ethanolic fermentation broth.

Furfural is an inhibitor of growth and ethanol production by Zymomonas mobilis. This study used a naturally occurring (not GMO) biological pre-treatment to reduce that amount of furfural in a model fermentation broth. Pre-treatment involved inoculating and incubating the fermentation broth with strains of Leuconostoc mesenteroides or Leuconostoc pseudomesenteroides. The Leuconostoc strains converted furfural to furfuryl alcohol without consuming large amounts of dextrose in the process. Coupling this pre-treatment to ethanolic fermentation reduced furfural in the broth and improved growth, dextrose uptake and ethanol formation. Pre-treatment permitted ethanol formation in the presence of 5.2 g L(-1) furfural, which was otherwise inhibitive. The pre-treatment and presence of the Leuconostoc strains in the fermentation broth did not interfere with Z. mobilis ethanolic fermentation or the amounts of ethanol produced. The method suggests a possible technique for reducing the effect that furfural has on the production of ethanol for use as a biofuel.