Competition For Nutrients Research Articles

The role of the gut microbiome in colonization resistance and recurrent Clostridioides difficile infection.

The Role of the Gut Microbiome in Clostridioides difficile Infection Introduction: A rich and diverse gut microbiome is key to immune system regulation and colonization resistance against pathogens.A disruption in the gut microbiome composition can make the gut more vulnerable to diseases such as Clostridioides difficile infection (CDI), caused by the bacterium C. difficile.CDI management presents a therapeutic dilemma, as it is usually treated with antibiotics that can treat the infection but also can damage the microbiome.Treatment of CDI using antibiotics can further reduce microbial diversity and deplete beneficial bacteria from the gut leading to a condition called dysbiosis.Antibiotic treatment can be followed by therapies that restore the gut microbiota, boost colonization resistance, and prevent the development of antimicrobial resistance.It is important to evaluate treatment options to determine their safety and effectiveness. Methods: The researchers provided an overview of the mechanisms that the gut microbiome uses to prevent colonization of the gut by pathogens.They subsequently reviewed the efficacy and shortcomings of the following treatments for CDI: - Antibiotics- Monoclonal antibodies- Fecal microbiota transplantation (FMT) Results: Commensal intestinal bacteria prevent colonization of the gut by pathogens using mechanisms such as: - Competition for key nutrients- Production of inhibitory bile acids- Short-chain fatty acid production- Lowering the luminal pH- Production of bacteriocinsAntibiotic therapy is recommended as a standard treatment for CDI. However, patients are vulnerable to recurrent CDI after discontinuation of the therapy.Monoclonal antibodies that inactivate C. difficile toxins may be recommended along with antibiotics to prevent recurrent CDI. However, this approach does not restore the microbiome.FMT is one method of microbial restoration, where stool is harvested from a healthy donor and transplanted into a patient's colon.Although FMT has shown some efficacy in the treatment of recurrent CDI, the procedure is not standardized.Safety concerns have been raised about the possibility of transmission of multidrug-resistant pathogens via FMT. Conclusion: Treatment methods that can efficiently restore the diversity of the gut microbiome are crucial in preventing recurrence of CDI.

Bacillus velezensis - biokontrolna aktivnost ćelija i ekstracelularnih jedinjenja protiv Xanthomonas spp

Bacillus velezensis is a novel biocontrol species exhibiting several mechanisms in biological control of plant pathogens, including antibiosis, production of other types of antimicrobials, such as volatile organic compounds, direct competition for nutrients and growth space, and induction of plant immunity towards pathogens. The aim of this study was to assess the potential of Bacillus velezensis IP22, cultivated on the optimized medium with glycerol as carbon source, for in vitro suppression of phytopathogenic bacteria - Xanthomonas campestris and Xanthomonas euvesicatoria. Different potential biocontrol agents were investigated: the overall cultivation broth, containing cells of Bacillus velezensis IP22 and produced extracellular metabolites, and cell-free supernatant obtained by centrifugation of the cultivation broth (10000 rpm, 10 min), which contained only the produced extracellular compounds. Furthermore, supernatant samples were subjected to heat treatment to assess whether there were thermosensitive extracellular compounds present in the supernatant. Vacuum evaporation was performed to concentrate supernatant samples in order to compare the effect of higher concentration of extracellular compounds to pathogens' growth. The results have indicated average inhibition zone diameters of 66.00 mm for the cultivation broth samples, 25.67 mm for the supernatants, 10.00 mm for the heat treated supernatants and 43.50 mm for the concentrated supernatants. Further research should include optimization of the production processes aimed at maximization of Bacillus velezensis IP22 growth and/or biosynthesis of the antimicrobial metabolites, as well as their precise identification and characterization to better understand the mechanism(s) of biocontrol activity against phytopathogenic Xanthomonas spp.

Main soil nutrients dynamics in sod-dressing intercropped orchard

The study aimed to estimate seasonal dynamics of soil nitrogen, phosphorus and potassium under the influence of sod grasses in a sod-dressing intercropped orchard. The trial was conducted in a Welsey apple 1987-year orchard. Trees were planted at 8×6 m, cultivar seedlings used as rootstock. Red clover and meadow timothy in variant shares were used for interrow sodding. The cereal—legume intercropping was done in 2015, preceded by a 180 kg/ha active substance phosphorus-potassium dressing in reserve. Nitrogen was applied annually prior to growing season at 34.4 kg/ha active substance. Grass biomass in first hay cutting was the highest and comprised 45.3-49.9 % total mass. A total four cuttings dry mass was 3.36-7.10 t/ha depending on scheme. The maximum biomass was registered for the schemes with red clover and meadow timothy at ratios 1:1 and 7:3 (6.52 and 7.10 t/ha). In the growing period, grass depleted soil for 111.1—219.9 kg/ha nitrogen, 21.5-42.7 kg/ha phosphorus and 209.3—380.8 kg/ha potassium. Such consumptions suggest a serious competition for soil nutrients between grass vegetation and fruit trees. The available phosphorus and potassium content was independent of interrow dressing schemes. Inter-scheme differences did not exceed experimental bias due to presowing phosphorus and potassium application in reserve before trial. By first cutting, the nitrate nitrogen soil content in sodding schemes was 1.5-2-fold less vs. bare fallow, i.e. more nitrogen is used by vegetating grass, and its available forms recover slower than being consumed.

Mechanism of the Gut Microbiota Colonization Resistance and Enteric Pathogen Infection.

The mammalian gut microbial community, known as the gut microbiota, comprises trillions of bacteria, which co-evolved with the host and has an important role in a variety of host functions that include nutrient acquisition, metabolism, and immunity development, and more importantly, it plays a critical role in the protection of the host from enteric infections associated with exogenous pathogens or indigenous pathobiont outgrowth that may result from healthy gut microbial community disruption. Microbiota evolves complex mechanisms to restrain pathogen growth, which included nutrient competition, competitive metabolic interactions, niche exclusion, and induction of host immune response, which are collectively termed colonization resistance. On the other hand, pathogens have also developed counterstrategies to expand their population and enhance their virulence to cope with the gut microbiota colonization resistance and cause infection. This review summarizes the available literature on the complex relationship occurring between the intestinal microbiota and enteric pathogens, describing how the gut microbiota can mediate colonization resistance against bacterial enteric infections and how bacterial enteropathogens can overcome this resistance as well as how the understanding of this complex interaction can inform future therapies against infectious diseases.

Influence of Different Herbicide Based Weed Management Practices on Growth and Yield of Flue Cured Tobacco in Northern Light Soils of Andhra Pradesh, India

Flue cured tobacco requires clean and weed free environment and thereby reduce the competition for nutrients and moisture for achieving quick early season growth. Deploying effective weed management practices play a key role in achieving better yields and quality. Field experiments were conducted at Peddpauram village of West Godavari district (Andhra Pradesh) during (Rabi) seasons of 2018-19 and 2019-20, to study the effect of different herbicide based weed management practices on growth and yield of flue cured Tobacco crop. The experiment was performed as Randomized Block Design with 11 weed management practices replicated thrice. The results recorded on growth parameters, in both the years revealed that six inter cultivations with two manual removal of weeds significantly impacted plant height (113.5 cm and 114.4 cm) and leaf area index (2.63 and 2.83) at 90 DAT over Imazethapyr applied at 0.05 kg a.i ha-1. Number of leaves plant-1 were higher with six inter cultivation and two manual removal of weeds (21.5 and 20.6) over Imazethapyr 0.05 kg a.i ha-1. Inter cultivations and manual weeding resulted in significantly enhancing yield attributes such as leaf thickness (0.143 mm and 0.143 mm for cutters and 0.183 mm and 0.173 for leaf) and lower leaf count (Number of leaves kg-1) (137 and 129) over weedy check. Application of Sulfentrazone 0.03 kg a.i ha-1 was comparable with inter cultivation and manual weeding. Sulfentrazone 0.3 kg a.i ha-1 contributed for significantly higher yield (2302 kg ha-1 and 2424 kg ha-1) over weedy check and comparable with six inter cultivations and two manual weeding operations. The application of pre emergence herbicides like Pendimethalin, Alachlor and Oxyflurfen resulted achieving higher yield levels over the application of post emergence herbicides such as Quiazalofop-p-ethyl, Fenoxaprop ethyl, Carfentrazone ethyl and Imazethapyr during both years of experimentation.

Performance of halotolerant bacteria associated with Sahara-inhabiting halophytes Atriplex halimus L. and Lygeum spartum L. ameliorate tomato plant growth and tolerance to saline stress: from selective isolation to genomic analysis of potential determinants.

The use of halotolerant beneficial plant-growth-promoting (PGP) bacteria is considered as a promising eco-friendly approach to improve the salt tolerance of cash crops. One strategy to enhance the possibility of obtaining stress-alleviating bacteria is to screen salt impacted soils. In this study, amongst the 40 endophytic bacteria isolated from the roots of Sahara-inhabiting halophytes Atriplex halimus L. and Lygeum spartum L., 8 showed interesting NaCl tolerance in vitro. Their evaluation, through different tomato plant trials, permitted the isolate IS26 to be distinguished as the most effective seed inoculum for both plant growth promotion and mitigation of salt stress. On the basis of 16S rRNA gene sequence, the isolate was closely related to Stenotrophomonas rhizophila. It was then screened in vitro for multiple PGP traits and the strain-complete genome was sequenced and analysed to further decipher the genomic basis of the putative mechanisms underlying its osmoprotective and plant growth abilities. A remarkable number of genes putatively involved in mechanisms responsible for rhizosphere colonization, plant association, strong competition for nutrients, and the production of important plant growth regulator compounds, such as AIA and spermidine, were highlighted, as were substances protecting against stress, including different osmolytes like trehalose, glucosylglycerol, proline, and glycine betaine. By having genes related to complementary mechanisms of osmosensing, osmoregulation and osmoprotection, the strain confirmed its great capacity to adapt to highly saline environments. Moreover, the presence of various genes potentially related to multiple enzymatic antioxidant processes, able to reduce salt-induced overproduction of ROS, was also detected.

Selection for Cell Yield Does Not Reduce Overflow Metabolism in Escherichia coli.

Overflow metabolism is ubiquitous in nature, and it is often considered inefficient because it leads to a relatively low biomass yield per consumed carbon. This metabolic strategy has been described as advantageous because it supports high growth rates during nutrient competition.Here, we experimentally evolved bacteria without nutrient competition by repeatedly growing and mixing millions of parallel batch cultures of Escherichia coli. Each culture originated from a water-in-oil emulsion droplet seeded with a single cell. Unexpectedly we found that overflow metabolism (acetate production) did not change. Instead, the numerical cell yield during the consumption of the accumulated acetate increased as a consequence of a reduction in cell size. Our experiments and a mathematical model show that fast growth and overflow metabolism, followed by the consumption of the overflow metabolite, can lead to a higher numerical cell yield and therefore a higher fitness compared with full respiration of the substrate. This provides an evolutionary scenario where overflow metabolism can be favorable even in the absence of nutrient competition.

Quantifying the role of moss in terrestrial ecosystem carbon dynamics in northern high latitudes

Abstract. Mosses are ubiquitous in northern terrestrial ecosystems, and play an important role in regional carbon, water and energy cycling. Current global land surface models that do not consider mosses may bias the quantification of regional carbon dynamics. Here we incorporate mosses as a new plant functional type into the process-based Terrestrial Ecosystem Model (TEM 5.0), to develop a new model (TEM_Moss). The new model explicitly quantifies the interactions between vascular plants and mosses and their competition for energy, water, and nutrients. Compared to the estimates using TEM 5.0, the new model estimates that the regional terrestrial soils currently store 132.7 Pg more C and will store 157.5 and 179.1 Pg more C under the RCP8.5 and RCP2.6 scenarios, respectively, by the end of the 21st century. Ensemble regional simulations forced with different parameters for the 21st century with TEM_Moss predict that the region will accumulate 161.1±142.1 Pg C under the RCP2.6 scenario and 186.7±166.1 Pg C under the RCP8.5 scenario over the century. Our study highlights the necessity of coupling moss into Earth system models to adequately quantify terrestrial carbon–climate feedbacks in the Arctic.

130. Design and Preclinical Characterization of SER-155, an Investigational Cultivated Microbiome Therapeutic to Restore Colonization Resistance and Prevent Infection in Patients Undergoing Hematopoietic Stem Cell Transplantation

BackgroundDuring allogeneic hematopoietic stem cell transplant (HSCT), the diversity and stability of the GI microbiome is disrupted, increasing the risk of domination by pathogens associated with bacteremia, aGvHD, and mortality. SER-155 is an investigational, oral microbiome therapeutic composed of cultivated spores and vegetative bacterial strains rationally designed to reduce the risk of bacteremia and aGvHD in HSCT recipients by decolonizing potential pathogens and restoring GI colonization resistance. SER-155 was evaluated in vitro for key pharmacological properties associated with colonization resistance, and in vivo to assess its ability to restore colonization resistance by reducing Enterococcus and Enterobacteriaceae carriage.MethodsThe design of SER-155 leveraged genomic data from interventional and observational human datasets to include taxa associated with reduced risk of infection and aGvHD in HSCT. Strains of interest were phenotyped, and over 50 candidate consortia containing different combinations of over 150 species were designed and tested in vitro and in vivo. In vivo, candidate compositions were evaluated in mouse models of vancomycin-resistant Enterococcus faecium (VRE) and carbapenem-resistant Klebsiella pneumoniae (CRE) colonization. ResultsOral administration of SER-155 led to a 2-3 Log10 reduction in VRE and CRE titers compared to untreated mice (Figure 1). In vitro, the carbon source utilization profile of VRE, CRE, and SER-155 strains were assessed using a panel of 85 carbon sources. All 56 carbon sources used by CRE or VRE for anaerobic growth were also utilized by SER-155 strains, supporting a model in which nutrient competition may contribute to reducing CRE and VRE carriage and restoring colonization resistance. Figure 1. SER-155 Efficacy in Mouse Models of VRE and CRE Colonization.The titers of VRE or CRE were quantified in fecal pellets by plating on selective agar at the indicated time-points. The median A) VRE and B) CRE CFU per gram of feces was calculated for each group and plotted on the line graph (n=6-10 per group). L.O.D., limit of detection. Data were analyzed using the Mann-Whitney t-test and significance was determined as a p-value of p< 0.05*, p<0.01**, p<0.001***, p<0.0001****.ConclusionSER-155 is an investigational cultivated microbiome therapeutic intended to reduce the risk of infection by engrafting human-commensal bacterial strains in adults undergoing allogeneic HSCT. Preclinical assessments in vitro and in vivo support the ability of SER-155 to reduce VRE and CRE carriage and restore colonization resistance in the gut. A Phase 1b study evaluating SER-155 in allogeneic HSCT patients is being planned. Disclosures Elizabeth Halvorsen, PhD, Seres Therapeutics (Employee, Shareholder) Marin Vulic, PhD, Seres Therapeutics (Employee) Edward J. O’Brien, PhD, Seres Therapeutics (Employee, Shareholder) Jessica Byrant, PhD, Seres Therapeutics (Employee, Shareholder) Mary-Jane Lombardo, PhD, Seres Therapeutics (Employee, Shareholder) Christopher Ford, PhD, Seres Therapeutics (Employee, Shareholder) Matt Henn, PhD, Seres Therapeutics (Employee, Shareholder)

Yield of sweet corn varieties and response to sulfonylurea and mix herbicides

Background Sweet corn is susceptible to weed competition for nutrients, moisture, and light interception. Herbicides labeled for use on sweet corn are limited. Hence, it is necessary to provide information about the POST sulfonylurea herbicides and mixtures and their different degrees of sensitivity in sweet corn varieties. Objective The objectives of this experiment were to evaluate the efficacy of sulfonylureas and nicosulfuron+bromoxynil/MCPA and mesotrione/s-metolachlor/terbuthylazine as post herbicide mixtures on broadleaves and grasses weed species, sweet corn grain yield and [...]

Antifungal activity and mode of action of lactic acid bacteria isolated from kefir against Penicillium expansum

Penicillium expansum is the most common spoilage-associated organism found in fruit, which causes serious economic loss and public health concerns. The aim of this study was to isolate lactic acid bacteria (LAB) from kefir in order to study its antifungal effect on mold growth and further analyze the possible antifungal mode of action of LAB, including antifungal component, lytic enzymes activity and nutrient competition. Lactobacillus kefiri M4 and Pediococcus acidilactici MRS-7 were isolated from kefir, and the overlay method was used as a qualitative approach to evaluate their antifungal activities against Penicillium expansum , the results showed that all tested strains were inhibited by the isolates, except for P. expansum LPH6. Different treatments were carried out to characterize the nature of the molecules that contributed to the antifungal activity of the cell-free supernatants produced by the isolates, and it was shown that all supernatants were pH-dependent, partly heat sensitive, and were not influenced by proteinaceous treatment. The cell-free supernatants of both species of LAB were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS), and it was found that the main antifungal compounds were organic acids and carboxylic acids. Both LAB species were able to produce lytic enzymes, such as cellulases, proteases, and glucanases, which formed a halo zone on the plate. L. kefiri M4 and P. expansum LPH10 exhibited nutrient competition when co-cultured together in a tissue culture plate insert. The results of this study showed that L. kefiri M4 and P. acidilactici MRS-7 isolated from kefir possess antifungal activity, which provides useful information of how P. expansum response to the LAB isolated from kefir. • Two LAB strains had antifungal effect on Penicillium expansum . • Organic acids and carboxylic acids were responsible for antifungal activity. • Both strains can produce cellulase, protease and glucanase. • L. kefiri M4 and P. expansum LPH10 have nutrients competition.

Perinatal complications and maximising lamb survival in an adolescent paradigm characterised by premature delivery and low birthweight.

The competition for nutrients in overnourished and still-growing adolescent sheep negatively impacts gestation length, colostrum supply and lamb birthweight, all of which may affect neonatal morbidity and survival to weaning. Herein perinatal complications and the requirement for supplementary feeding were analysed in relation to gestational-intake, and the degree of premature delivery and prenatal growth-restriction exhibited. Pregnancies were established by embryo transfer and the mean/standard deviation (SD) gestation length and birthweight of the optimally-fed control group (n = 100) was used to define early delivery and reduced birthweight categories (1.5 and 3.0 SDs below the control mean for each aspect). Control lambs were largely delivered at term (94%), and had a normal birthweight (92%), while very preterm (≤139days, 18.5%) and preterm delivery (140-142days, 54.8%), extremely low birthweight (ELBW; females ≤2838g and males ≤3216g, 21.1%) and low birthweight (LBW; females 2839 to ≤4001g and males 3217 to ≤4372g, 32.2%), were common in the overnourished group (n = 270, P<0.001). Accordingly, overnourished dams were more likely to lamb without assistance while the incidence of major dystocia was greater in controls. Initial lamb vigour at birth was independent of gestational-intake, delivery or birthweight category but both ELBW and very premature lambs required more assistance with feeding in the first 24h postnatal, primarily reflecting low colostrum availability. Indeed, relative to normal, ELBW lambs had a greater risk of experiencing mismothering, and enhanced likelihood of requiring supplementary feeding throughout the neonatal period (P<0.001). ELBW lambs also had a greater possibility of respiratory issues at birth (P<0.01) and renal complications (P<0.001), while very preterm delivery was associated with an increased risk of gastrointestinal tract problems (P<0.01). In spite of these complications, all-cause mortality was low (5.4%) suggesting that our proactive neonatal care regime can overcome many of the issues associated with extreme prematurity and low birthweight.

Volume, biomass, carbon sequestration and potential of desert lands’ afforestation irrigated by wastewater on examples of three species

A study was conducted on three species (Khaya senegalensis, Corymbia citriodora and Casuarina equisetifolia) planted in desert lands of Egypt and irrigated with basic treated municipal wastewater. Every single tree is permanently drip irrigated and at the same time fertilised by the nutrient-rich wastewater. Trees of different classes of the diameter at breast height (eight for each species) were felled to determine the form factor and stem volume, as well as the biomass and carbon sequestration of stem, crown and root of the individual trees. In addition, a scenario for the development of un-thinned stands from ages 5 to 35 years was constructed. The age of the sample trees at felling was: 128, 66 and 82 months for K. senegalensis, C. citriodora and C. equisetifolia, respectively. The vigorous sampled trees had a stem volume of 0.289, 0.162 and 0.229 m3 and an aboveground and belowground biomass of 451, 161 and 264 kg for K. senegalensis, C. citriodora and C. equisetifolia, respectively. Results of the scenario showed an unexpectedly high growth rate of afforestation in desert lands using municipal wastewater. At the age of 25, the stem volume for all three species exceeds 398 m3/ha. At the same age of 25 years, K. senegalensis, C. citriodora and C. equisetifolia sequester 1131, 1068 and 860 CO2 t/ha, respectively. Afforestation in desert areas presents a unique situation in forestry, as growth is stimulated by sufficient sunlight, water and nutrients. Competition for water and nutrients is strongly diminished. Self-thinning of stands under such conditions is expected to be much slower than in rain-fed plantation forests. On the other hand, tree maturity span is curtailed. This opens new possibilities for different forest management and practices towards resilient forest-based mitigation of climate change. For its unexpected role as an effective mitigation measure, afforestation in desert lands should be encouraged and further research conducted.

Control of Penicillium expansum by an Epiphytic Basidiomycetous Yeast

Postharvest biocontrol agents are considered a viable alternative to the use of synthetic chemicals as demonstrated by extensive research conducted by scientists and companies worldwide. In the present investigation, the biocontrol potential of a carotenoid-producing basidiomycetous yeast isolated from table grape flowers was analyzed. The strain RY1 proved to be Sporobolomyces roseus. In vitro and in vivo tests were conducted to assess its efficacy against Penicillium expansum, one of the most important postharvest pathogens and producer of the mycotoxin patulin. The yeast proved to control both fungal growth and patulin production, and, in addition, to greatly affect disease incidence and severity on apples. Its mode of action is presumably related both to the competition for nutrients and the production of antifungal volatiles. As such, although further large-scale trials are needed, our S. roseus strain represents a potential interesting biocontrol agent to be applied after harvest.

Relative roles of fundamental processes underpinning PEG dynamics in dimictic lakes as revealed by a self-organizing, multi-population plankton model

The longstanding PEG (Phytoplankton Ecology Group) qualitative/conceptual model describes generalized seasonal phytoplankton dynamics in temperate lakes and suggests important mechanisms driving these processes. In the research presented here, we re-created the conceptual PEG dynamics using a novel mechanistic numerical plankton model. The numerical model incorporates only a handful of interacting factors and biological rules. Key model features include seasonally variable temperature, mixing depth, and light, dynamic zooplankton and phytoplankton populations, and multiple dynamic nutrient concentrations. The model design is unique in that it incorporates a population-rich phytoplankton assemblage where life-history traits of members are based on ecological principles (trade-offs between traits), allowing the assemblage to organize over time based on nutrient competition and grazing. Using 50th year solutions to the model solved with fourth-order Runge-Kutta methods, i.e., a period when the dynamics had reached stable non-equilibrium states, sensitivity analyses were run by individually varying model parameters +/- 50% and comparing the effect on model responses of interest. Simulation analyses revealed the important role light and temperature limitation played both early and late in the year controlling plankton biomass. Trade-offs in phytoplankton life-history characteristics determined the composition of the spring bloom under non-nutrient limiting conditions (fast-growing, edible populations dominated) and the post clear-water phase assemblage under low nutrient conditions (slower-growing, less-edible populations dominated). Grazer characteristics, specifically rate of grazing and spring “emergence”, determined the occurrence of the clear-water phase and influenced the post assemblage composition, where a clear-water phase was absent when the grazing rate was low or spring emergence absent, and the highly inedible populations were lost from the assemblage. Hydraulic flushing also played an important role where diminished inflow led to higher richness, evenness and diversity due to greater overwintering of less-edible taxa, which influenced phytoplankton composition during spring bloom, diminishing secondary productivity. These results increase understanding of the relative roles of fundamental mechanisms structuring natural aquatic ecosystems and reinforce the significance of key biotic and abiotic system components of temperate lakes.

Farmer Perceptions of Adopting Novel Legumes in Traditional Maize-Based Farming Systems in the Yucatan Peninsula

Intercropping constitutes the traditional farming system practice used in various forms for maize production in the Yucatan peninsula. Although practiced for centuries, problems persist with competition for water, nutrients and light between crop species in traditional farming systems. Furthermore, little is known about farmers’ perceptions regarding changes to traditional maize-legume intercropping systems and their interest in novel crop adoption to increase yields in the system while maintaining the practice. The objective of this study was to investigate the maize-based traditional cropping system by assessing the underlying motives and concepts of farmers to practice intercropping in the Yucatan Peninsula and to examine the association between farmers’ level of knowledge about legumes and decisions to adopt intercropping and related practices therein. Farmer surveys were conducted in nine different regions of the Yucatan Peninsula. We selected Xoy, Euan, Muna, Mama, Tahdziú (Yucatan), Becal, Hecelchacam, Dzitbalché and San Antonio Sahcabchén (Campeche) which are representative of agroecological small-scale farming systems. We used a mixed methods case study analysis involving key informant interviews in eight associations of farmers. A sample frame with 73 farmers was selected in total during February 2021 and April 2021. Basic information such as land use, labor inputs, agricultural production and farmer’s perceptions regarding their intercropping systems were collected. Our research shows that the primary motives for intercropping were due to the ability of intercropping to offer a more diversified range of food for human and animal consumption, as well as to take advantage of different harvest periods that this practice offers. The majority of respondents were likely to favor the idea of introducing new legume species in their maize-based cropping systems. Factors such as the type of cropping system (i.e., intercropping or monocropping), access to water and level of knowledge about legumes influenced their decision to adopt intercropping in their farming systems considerably. This paper contributes to the knowledge on the current state and farmers’ perceptions of intercropping systems in the Yucatan Peninsula.

Mixing degree, stand density, and water supply can increase the overyielding of mixed versus monospecific stands in Central Europe

Tree species mixtures can overyield monospecific stands and provide many other advantageous regulating and provisioning ecosystem services. So far, the effect of mixing on growth were mostly described at the individual tree level or cumulatively at the stand level. How overyielding emerges from the mixing pattern, how it is modulated by the current environmental conditions, and how overyielding develops with progressing stand age is largely unexplored. However, such knowledge might promote the silvicultural design of mixed stands.Here, we use 50 long-term experimental plots in Germany with repeated spatially explicit stand inventories. They cover monospecific and mixed species stands of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.), sessile oak (Quercus petraea [Matt.] Liebl.) and European beech, and Scots pine (Pinus sylvestris L.) and European beech. The stands represent medium to very good site conditions, fully to moderately thinned 15–238 years-old stands with mixing patterns ranging from single-tree and group-mixture to monospecific stands.The main hypothesis is that mixing pattern, environmental conditions, and stand age modulate the stand growth and overyielding of mixed versus monospecific stands. Based on metrics of mixing the mixing pattern and indices of environmental conditions we show that mixed stands of European beech were on averaged by 12–36% more productive than respective monocultures. Overyielding can increase with stand density, mixing degree, regularity of horizontal tree distribution, tree size variation, site index, and water supply. Overyielding continued throughout the whole rotation time.The found overyielding suggests general facilitative effects of mixing in terms of bioclimate or soil conditions, independent of the mixing pattern. In addition to this general effect, overyielding was increased by stand density and mixing degree. This suggests a strong competition reduction due to structural complementarity. That the overyielding increases in moist years, points to the competition reduction as dominant cause. We hypothesize that in moist years competition for light and nutrient becomes stronger, so that species complementarity is more important and competition reduction may operate stronger and more beneficial for growth than in years with growth limitation by water.The findings stress the relevance of spatially explicit approaches of analyzing and modelling facilitation and competition at the stand and tree level. Silvicultural prescriptions may incorporate the findings that the analyzed mixtures with European beech in general overyield monospecific stands and that the benefit can be further increased by stand density, mixing degree, and tree size variation. Beneficial effects of mixtures can be expected on medium to high quality sites, in dry years, and even more in moist periods.

APSIM model performance in simulating Piatã palisade grass growth and soil water in different positions of a silvopastoral system with eucalyptus

CONTEXTSilvopastoral systems aim to be more sustainable than conventional systems, increasing total productivity, diversifying agricultural production, and improving resource use efficiency. However, very few studies were performed to adapt crop models to simulate these systems. OBJECTIVEThis study investigates the current capacity of the APSIM Next Generation model to estimate Piatã palisadegrass growth and soil water in different positions in a silvopastoral system with eucalyptus by looking at the impact of modelling belowground and aboveground competition separately. METHODSA field experiment was conducted from December 2014 to January 2016 in a silvopastoral system with eucalyptus trees arranged in single rows, in East-West orientation, with 15 m between rows and 2 m between trees in the rows. This experiment was conducted under grazing management and rainfed conditions, during 11 growth cycles, with pasture variables, soil moisture and microclimatic conditions assessed at four distances from the eucalyptus north row (0.00 m, 3.75 m, 7.50 m and 11.25 m). APSIM testing was performed in two ways: focusing on belowground competition for soil water and nitrogen, using a multi-root-zone approach, and focusing on competition for solar radiation, using the measured data of solar radiation at each position. RESULTS AND CONCLUSIONSThe APSIM-Tropical Pasture model was effective in simulating pasture growth when only competition for solar radiation was considered (R2 from 0.75 to 0.86, Agreement index (d) from 0.88 to 0.96, and Nash-Sutcliffe efficiency (NSE) between 0.32 and 0.85). These simulations are promising taking into account the difficulties to simulate pasture growth in silvopastoral systems with grazing; however, in systems with strong belowground competition for soil water and nutrients, this approach has strong limitations. Simulations of pasture growth were not as effective when using the multi-root-zone approach (R2 between 0.57 and 0.87, d between 0.53 and 0.74, and NSE from −5.32 to −1.20), despite reasonable simulations of soil water for the positions between the tree rows (R2 between 0.70 and 0.80, d from 0.91 to 0.94, and NSE between 0.60 and 0.77). In view of these results, improvements should be performed in APSIM to better simulate silvopastoral systems, mainly for solar radiation transmission and tree roots growth and distribution. SIGNIFICANCEThis study allowed identifying the key drivers of competition within the studied environment and to inform where the main efforts should be targeted in building a more effective model for silvopastoral systems. This is important to help model development teams in organising and optimising their efforts.

Development of fungal-mediated soil suppressiveness against Fusarium wilt disease via plant residue manipulation

BackgroundThe development of suppressive soils is a promising strategy to protect plants against soil-borne diseases in a sustainable and viable manner. The use of crop rotation and the incorporation of plant residues into the soil are known to alleviate the stress imposed by soil pathogens through dynamics changes in soil biological and physicochemical properties. However, relatively little is known about the extent to which specific soil amendments of plant residues trigger the development of plant-protective microbiomes. Here, we investigated how the incorporation of pineapple residues in soils highly infested with the banana Fusarium wilt disease alleviates the pathogen pressure via changes in soil microbiomes.ResultsThe addition of above- and below-ground pineapple residues in highly infested soils significantly reduced the number of pathogens in the soil, thus resulting in a lower disease incidence. The development of suppressive soils was mostly related to trackable changes in specific fungal taxa affiliated with Aspergillus fumigatus and Fusarium solani, both of which displayed inhibitory effects against the pathogen. These antagonistic effects were further validated using an in vitro assay in which the pathogen control was related to growth inhibition via directly secreted antimicrobial substances and indirect interspecific competition for nutrients. The disease suppressive potential of these fungal strains was later validated using microbial inoculation in a well-controlled pot experiment.ConclusionsThese results mechanistically demonstrated how the incorporation of specific plant residues into the soil induces trackable changes in the soil microbiome with direct implications for disease suppression. The incorporation of pineapple residues in the soil alleviated the pathogen pressure by increasing the relative abundance of antagonistic fungal taxa causing a negative effect on pathogen growth and disease incidence. Taken together, this study provides a successful example of how specific agricultural management strategies can be used to manipulate the soil microbiome towards the development of suppressive soils against economically important soil-borne diseases.CyJuYsbKET__Z9ZHp7dVcVVideo

A Complex Metabolic Network Confers Immunosuppressive Functions to Myeloid-Derived Suppressor Cells (MDSCs) within the Tumour Microenvironment.

Myeloid-derived suppressor cells (MDSCs) constitute a plastic and heterogeneous cell population among immune cells within the tumour microenvironment (TME) that support cancer progression and resistance to therapy. During tumour progression, cancer cells modify their metabolism to sustain an increased energy demand to cope with uncontrolled cell proliferation and differentiation. This metabolic reprogramming of cancer establishes competition for nutrients between tumour cells and leukocytes and most importantly, among tumour-infiltrating immune cells. Thus, MDSCs that have emerged as one of the most decisive immune regulators of TME exhibit an increase in glycolysis and fatty acid metabolism and also an upregulation of enzymes that catabolise essential metabolites. This complex metabolic network is not only crucial for MDSC survival and accumulation in the TME but also for enhancing immunosuppressive functions toward immune effectors. In this review, we discuss recent progress in the field of MDSC-associated metabolic pathways that could facilitate therapeutic targeting of these cells during cancer progression.