Inoculum Dose Research Articles

Co-inoculation of Rhizobium and Bradyrhizobium promotes growth and yield of common beans

Some strains of Bradyrhizobium benefit the biological N2 fixation (BNF) and growth of common beans (Phaseolus vulgaris L.) when co-inoculated with Rhizobium tropici under greenhouse conditions. Here, we evaluated the benefit of Bradyrhizobium diazoefficiens strain CPAC 7 co-inoculated with Rhizobium tropici strain CIAT 899 on common bean in the field. Three Bradyrhizobium strains were co-inoculated with R. tropici CIAT 899 in one experiment in the greenhouse and two in the field. The greenhouse experiment combined each of three Bradyrhizobium strains (29w, USDA 110, and CPAC 7) in co-inoculation with CIAT 899 in Leonard jars. Then, two of these strains, 29w and CPAC 7, were co-inoculated with Rhizobium on-seeds (1.2 × 106 CFU seed−1) or both on-seed and in-furrow (1.08 × 108 CFU m−1) in a field experiment. Finally, a second field experiment evaluated strain CPAC 7 at doses ranging from 1.5 × 105 to 1.2 × 106 CFU seed−1. Co-inoculation with strain CPAC 7 improved shoot biomass accumulation in Leonard jars. In the field, co-inoculation of CPAC 7 with CIAT 899 on-seed enhanced grain yield by 20% compared with inoculation of CIAT 899 only (p < 0.10). The percentage of N derived from the air (%Ndfa) was between 50 and 60%, with only a tendency towards co-inoculation benefit. Given that the %Ndfa of the inoculated plants was not statistically different between treatments, the increased grain yield was not entirely due to BNF but also due to an increase of soil N uptake. In the second field trial, larger doses of inoculum increased nodulation and root biomass, but significant differences in grain yield were not observed. Our results show that the Rhizobium-Bradyrhizobium co-inoculation can enhance growth and grain yield of common beans and indicate that a plant growth-promoting mechanism besides BNF may be involved in the beneficial co-inoculation effect. However, further adjustments are needed to ensure a better response under field conditions.

411. Significance of a Known Epidemiological Link to a COVID-19 Index Case and Severity of COVID-19 Infection

Abstract Background Several factors have been associated with severity of COVID-19 disease, but there remains a paucity of data surrounding whether the nature of exposure is impactful. Evidence demonstrating the correlation between initial viral exposure dose and disease severity exists for many viral infections. Observational studies have suggested that the exposure context, which can be considered a proxy for magnitude of viral inoculum, may influence severity of COVID-19 infection. We aimed to assess whether having a known exposure, as a proxy for higher inoculum dose to COVID-19, was associated with more severe outcomes for individuals hospitalized with COVID-19. Methods We created a retrospective cohort of community-dwelling adults hospitalized for COVID-19 in south-central Ontario from April 1, 2020 - January 14, 2021. Individuals or next of kin were contacted to ascertain exposure history. The primary outcome was death, intensive care unit (ICU) admission, or mechanical ventilation (MV) within 30 days of admission. A multivariable logistic regression model was used to determine whether a known exposure was associated with worse outcomes. Results 1097 individuals with community acquired COVID-19 required hospitalization; of these, 942 (86%) had available exposure data. In this group, the median age was 65, 44% were women, 84% lived in a private residence, 59% had a frailty score (FS) of 1 – 3 while 40% had a FS of 4 – 9, and 28% had a known exposure. Overall, the primary outcome occurred in 368/942 (39%) patients. Having a known exposure was not associated with worse outcome (OR 1.14, 95% CI 0.84–1.54, p = 0.41). Male gender (OR 1.41, 95% CI 1.06–1.89; p = 0.018), age (OR 1.01/year, 95% CI 1.00–1.03, p = 0.03), frailty (OR 1.22/point, 95% CI 1.09–1.36, p = 0.001) and living with at least one other person (OR 1.57, 95% CI 1.09–2.28, p = 0.017) were all associated with death, ICU admission, or MV within 30 days of admission. Conclusion While having a known exposure to a person with COVID-19 was not associated with worse outcome, the identified increased severity of illness associated with cohabitation suggests context of exposure may have a role in disease severity. This data and future studies can be used to guide public health recommendations to not only minimize transmission, but severity of COVID-19 infection. Disclosures All Authors: No reported disclosures

Calcium alginate–bentonite/activated biochar composite beads for removal of dye and Biodegradation of dye-loaded composite after use: Synthesis, removal, mathematical modeling and biodegradation kinetics

Present study aimed to the production of calcium alginate–bentonite/activated biochar beads for implementation in methylene blue (MB) dye removal process and biodegradation study of dye-loaded composites by isolated bacteria, Lysinibacillus Sp . FTIR, TGA, SEM analysis of synthesized polymeric composite and biodegraded dye-loaded composite were performed to evaluate the surface characteristics and to identify the changes in biodegraded sample after biodegradation process. Experimental data of batch study were seemed to be extensively adjacent with the Langmuir isotherm and the maximum capacity for monolayer biosorption was 47.393 mg g − 1 at 303 K and with increasing temperature, it was decreased. Additionally, the biosorption kinetics confirmed that the pseudo 2nd order model was comparatively more applicable than pseudo 1st order, Elovich diffusion and Weber–Morris intraparticle model for describing MB biosorption. Estimated magnitude of thermodynamic variables specified that the MB dye removal system was favorable at lower temperatures and endothermic process. Biodegradation study of dye-loaded composite was carried out under different operational conditions (pH, inoculum dosage, temperature, etc.) and high biodegradation efficiency was found (% weight loss >70%). Experimental data obtained from biodegradation kinetics was modeled by applying Han and Levenspiel’s model and estimated values of μ max and K S as 0.0897 h −1 and 0.102 gL −1 , respectively. The calculated value of Y x/s was obtained as 67.6 g of biomass/g of dye-loaded composite. • Application of Ca-alginate–bentonite/activated biochar in decolorization process. • Biodegradation study of dye-loaded composites by Lysinibacillus Sp . • FTIR, TGA, SEM of composite and biodegraded dye-loaded composite were analyzed. • Biosorption isotherm, Biosorption kinetics, and Thermodynamic study were evaluated. • Biodegradation kinetics was modeled by applying Han and Levenspiel’s model.

Tandem Mass Tag-Based Quantitative Proteomics and Virulence Phenotype of Hemolymph-Treated Bacillus thuringiensis kurstaki Cells Reveal New Insights on Bacterial Pathogenesis in Insects.

ABSTRACTThe spore-forming bacterium Bacillus thuringiensis (Bt) of the Bacillus cereus group uses toxin-opened breaches at the insect midgut epithelium to infest the hemolymph, where it can rapidly propagate despite antimicrobial host defenses and induce host death by acute septicemia. The response of Bt to host hemolymph and the latter’s role in bacterial pathogenesis is an area that needs clarification. Here, we report a proteomic analysis of the Bt kurstaki strain HD73 (Btk) hemolymph stimulon showing significant changes in 60 (34 up- and 26 downregulated) differentially accumulated proteins (DAPs). Gene ontology (GO) enrichment analysis revealed that DAPs were mainly related to glutamate metabolism, transketolase activity, and ATP-dependent transmembrane transport. KEGG analysis disclosed that DAPs were highly enriched in the biosynthesis of bacterial secondary metabolites, ansamycins. Interestingly, about 30% of all DAPs were in silico predicted as putative virulence factors. Further characterization of hemolymph effects on Btk showed enhanced autoaggregation in liquid cultures and biofilm formation in microtiter polystyrene plates. Hemolymph-exposed Btk cells were less immunogenic in mice, suggesting epitope masking of selected surface proteins. Bioassays with intrahemocoelically infected Bombyx mori larvae showed that hemolymph preexposure significantly increased Btk toxicity and reproduction within the insect (spore count per cadaver) at low inoculum doses, possibly due to ‘virulence priming’. Collectively, our findings suggest that the Btk hemolymph stimulon could be partially responsible for bacterial survival and propagation within the hemolymph of infected insects, contributing to its remarkable success as an entomopathogen. All mass spectrometry data are available via ProteomeXchange with identifier PXD021830.IMPORTANCE After ingestion by a susceptible insect and damaging its midgut epithelium, the bacterium Bacillus thuringiensis (Bt) reaches the insect blood (hemolymph), where it propagates despite the host’s antimicrobial defenses and induces insect death by acute septicemia. Although the hemolymph stage of the Bt toxic pathway is determinant for the infested insects’ fate, the response of Bt to hemolymph and the latter’s role in bacterial pathogenesis has been poorly explored. In this study, we identified the bacterial proteins differentially expressed by Bt after hemolymph exposure. We found that about 30% of hemolymph-regulated Bt proteins were potential virulence factors, including manganese superoxide dismutase, a described inhibitor of hemocyte respiratory burst. Additionally, contact with hemolymph enhanced Bt virulence phenotypes, such as cell aggregation and biofilm formation, altered bacterial immunogenicity, and increased Bt toxicity to intrahemocoelically injected insects.

Evaluation of Bacillus amyloliquefaciens UG7 in improving cassava leaf meal as a raw material for fish feed

Cellulolytic bacteria can be used to improve the quality of cassava leaf meal by reducing fiber and simplifying other nutrients such as protein and carbohydrate. The use of this cellulolytic bacteria will have an impact on increasing the digestibility of the material so that its utilization as feed raw material can be increased. This study aimed to evaluate the ability of cellulolytic bacteria Bacillus amyloliquefaciens UG7 in improving the quality of cassava leaf meal as raw material for fish feed. The study was conducted using a completely randomized design (CRD) with 4 treatments and 3 replications. The treatment was cassava leaf meal fermented using B. amyloliquefaciens UG7 that isolated from Turbinaria with four doses of inoculum, namely 0%, 5%, 10%, 15%. Cassava leaf meal incubation was carried out at 28°C (room temperature) for 3 days. The parameters observed were reducing sugar, water-soluble protein, crude fiber, digestibility. The results showed that the use of these bacteria can increase reducing sugars, water-soluble proteins and reduce the crude fiber content of cassava leaf meal. A dose of 15% bacteria yields the highest value for water-soluble protein and reducing sugar and produces the lowest value for crude fiber content. However, the fermentation process of cassava leaf meal with B. amyloliquefaciens did not significantly influence the total digestibility of material.

Effects of supplementation with a Pichia guilliermondii yeast cell product or essential oils on performance and health of dairy calves during an experimental coccidial infection

This study was conducted to determine whether an inactivated whole-cell yeast product derived from Pichia guilliermondii (PG; CitriStim, Pancosma, a brand of Archer Daniels Midland Co.) or an essential oil blend (EO) primarily composed of carvacrol and cinnamaldehyde (Pancosma, a brand of Archer Daniels Midland Co.) could be used to mitigate the severity of an experimental coccidial infection in young dairy calves. A 10-wk experiment was conducted using 38 Holstein bull calves (39.5 ± 5.7 kg) fed a typical commercial 20:20 milk replacer (Dairy Manufacturers Inc.) regimen (500 g/d). Calves were randomly assigned to 1 of 5 treatments: uninfected control (PC) and 4 treatments that received experimental coccidial infections: infected control (NC; no additives); PG at 2 g/head per d (PG2); PG at 6 g/head per d (PG6); and EO at 0.28 g/head per d. Feed additives were provided in the milk replacer and supplementation started when calves were approximately 2 wk of age. On d 35 of the trial, each infected calf was administered a single oral dose of a mixed inoculum of 5 Eimerial oocysts. Calves were weighed upon arrival, before inoculation, and weekly before morning feeding. Fecal scores were visually monitored daily using a scoring system with a scale of 1 to 5. Body temperature was measured 1 per wk for 5 wk following inoculation. To assess oocyst numbers, beginning on d 4 postinoculation, feces were collected daily until d 35. To determine the extent of intestinal damage caused by coccidial infections, 1 calf per treatment was randomly killed on d 7 and 2 calves per treatment were killed on d 21 postinoculation. All infected calves scoured with equal severity, which was statistically significant when compared with noninfected calves ( P < 0.05). Calves fed either PG6 or EO tended to have greater intake compared with NC and PG2 calves (6.65 and 6.52 kg vs. 2.92 and 2.94 kg, respectively; P = 0.057). In addition, gain tended to be greater for calves fed either PG6 or EO (16.7 and 15.4 kg) compared with NC and PG2 calves ( P = 0.097). Fecal oocyst shedding peaked at 7 d (phase 1) and 21 d (phase 2) postinoculation. In phase 1, PG6 reduced ( P < 0.05) oocyst counts compared with NC; however, by phase 2, oocyst counts did not differ across all infected calves. When lesion scores across all intestinal segments were analyzed, calves given either PG2 or PG6 had lower ( P < 0.05) lesion scores than either NC calves or calves given EO. Calves supplemented with PG showed marked benefits on intestinal health, whereas calves supplemented with EO had modest benefits under coccidia infection. These data further suggest that natural feed additives may be alternatives for antibiotics during coccidiosis challenges.

Critical Evaluation of Two Commercial Biocontrol Agents for Their Efficacy against B. cinerea under In Vitro and In Vivo Conditions in Relation to Different Abiotic Factors

The study evaluated the dose–response relationship of two commercial microbial biocontrol agents, Bacillus subtilis and Gliocladium catenulatum, against Botrytis cinerea both in vitro and in vivo. Inoculum doses, formulation, temperature and foliar leaf part all affected the control achieved by the two BCAs. In vitro competition assays on modified PDA plates tested a range of BCA doses (log10 3–10 CFUs or spores/droplet) at 4, 10 and 20 °C on the development of B. cinerea colonies. The dose–response relationship was influenced by both the BCA formulation and temperature. In vivo studies on lettuce plants in semi-commercial greenhouses examined the BCA dose (log10 5–9 CFUs or spores/mL) for controlling B. cinerea with a high inoculum (log10 6 spores/mL). Leaf disc assays showed that the dose–response relationship was influenced by the leaf parts sampled. These results suggest that the dose–response relationship between a BCA and specific pathogen will be significantly influenced by environmental conditions, formulation and plant phyllosplane tissue.

The use of sludge as a micronutrient for the improvement of biogas production from seaweed: the integration of two sources of environmental concern to bring new opportunities

AbstractLarge quantities of seaweed in marine environments and coastal areas can cause serious hygienic and environmental problems. Anaerobic digestion (AD) could provide a solution and could also be useful for the production of bioenergy and fertilizer. However, the AD of algae biomass has some limitations and further work is required on the process. To increase the efficiency of the process, batches of 350 mL feedstock containing seaweed biomass (Sargassum sp.), inoculum, and different dosages of sludge from drinking water treatment (DWTS) as a micronutrient source to improve biogas production were digested in a 500 mL glass reactor and under mesophilic conditions, leading to significantly enhanced methane production. The highest methane yield (199 NmL g−1 VS) was observed when 6 mg L−1 DWTS was added, which showed a 30% improvement compared with the control digester and accounted for a 249.4 kWh increase in net energy per ton. The biodegradability index also increased by 10% compared with the control after the addition of DWTS. © 2021 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Effects of Temperature and Wetness Duration on Infection by Coniella diplodiella, the Fungus Causing White Rot of Grape Berries.

Grapevine white rot, caused by Coniella diplodiella, can severely damage berries during ripening. The effects of temperature and wetness duration on the infection severity of C. diplodiella were investigated by artificially inoculating grape berries through via infection pathways (uninjured and injured berries, and through pedicels). The effect of temperature on incubation was also studied, as was that of inoculum dose. Injured berries were affected sooner than uninjured berries, even though 100% of the berries inoculated with C. diplodiella conidia became rotted whether injured or not; infection through pedicels was less severe. On injured berries, the disease increased as the inoculum dose increased. Irrespective of the infection pathway, 1 h of wetness was sufficient to cause infection at any temperature tested (10–35 °C); with the optimal temperature being 23.8 °C. The length of incubation was shorter for injured berries than for uninjured ones, and was shorter at 25–35 °C than at lower temperatures; the shortest incubation period was 14 h for injured berries at 30 °C. Mathematical equations were developed that fit the data, with R2 = 0.93 for infection through any infection pathway, and R2 = 0.98 for incubation on injured berries, which could be used to predict infection period and, therefore, to schedule fungicide applications.

PENENTUAN KONDISI OPTIMUM PRODUKSI ENZIM KERATINASE OLEH Actinobacillus spp. MENGGUNAKAN TEPUNG BULU AYAM SEBAGAI SUBSTRAT PADA FERMENTASI MEDIA CAIR

Keratinase enzyme is a monomeric enzyme, this enzyme can hydrolyze keratin protein found in chicken feathers. It is estimated that about 90% of the protein contained in chicken feathers is keratin protein, this protein is difficult to digest because of the strong disulfide cross-links and other bonds. Biological processing of chicken feather flour with enzyme treatment produced by microorganisms during the fermentation process under optimal conditions produces high quality feather flour. There are several factors that affect the activity of the keratinase enzyme, including: dose inoculum, temperature, pH, substrate concentration, enzyme deposition, and fermentation time. This study aims to obtain the best optimum conditions (pH, substrate concentration, inoculum dose and fermentation time) of Actinobacillus spp in producing keratinase enzymes using chicken feather flour as a substrate in liquid medium. The main ingredients used in this study are: chicken feather flour, NA (Nutrient Agar), Aquades and substances used for liquid media and bacteria Actinobacillus spp. The study used an experimental method with 4 treatments consisting of pH (9.0; 9.5; 10; 10.5 and pH 11), sedimentation substrate (0.5%; 1%; 1.5%; 2%; 2 ,5%), inoculum dose (1 ml, 1.5 ml, 2 ml, 2.5 ml, 3 ml) and fermentation time 1 to 7 days, each treatment was repeated 3 times. The results showed that the optimum fermentation conditions of Actinobacillus spp in producing keratinase enzyme with an optimum pH of 9, optimum substrate concentration of 1%, inoculum dose of 1.5 ml, and optimum fermentation time of 2 days. Keyword : Actinobacillus spp; chicken feather flour; keratinase enzyme activity; optimumcondition

Influence of Different Species of Steinernema and Heterorhabditis on Galleria mellonella and Spodoptera littoralis

Entomopathogenic nematodes (EPNs) can be used efficiently as biological control agents against specific insects. Galleria mellonella (Gm) and Spodoptera littoralis (Sl) are considered important agricultural pests. The aim of this study was to evaluate the susceptibility of their larvae to ascending levels of four species of EPNs, Steinernema carpocapsae (Sc), S. arenarium (Sa), Heterorhabditis bacteriophora (Hb) and H. indica (Hi) as well as the ability of nematodes to penetrate and reproduce within their hosts. Fifth larval instar of Gm and Slwere used to evaluate the effect of four inoculum doses [200,400,800, and 1600 infective juveniles (IJs)] of each nematode species. Percentage of insect mortality (% M) and the nematode-rate of reproduction (Rr) were calculated after 24 and 48 hrs. The data confirmed that H. bacteriophora was the highest effective species on both insects. The % M was 75.7, 79.7, 82.3, and 83% after 24 hrs and 98.0, 99.3,100 and 100% after 48 hrs in Gm for these doses, respectively. On the other hand, the corresponding mortalities were 75.0, 78.3, 81.7, and 83.8% after 24 hrs and 97.3, 98.3, 100 and 100% after 48 hrs in Sl. The highest initial EPN population that could penetrate the insect (pi) was achieved by HbinGm (295 IJs) at 1600 IJs, while it was 221.7 IJs in Sl larvae at the same inoculum. The highest final population and Rr were obtained at the inoculum level of 200 and 400 IJs. in Gm and Sl, respectively.The study documented that Heterorhabditis and Steinernema can be used effectively in Gmand Sl management. Moreover, Hb is the most suppressive species tested against the two lepidopteran hosts.

Effect of dose and time of saline-tolerant Rhizobium sp. inoculation to productivity of black soybean (Glycine soja (l) merrit) on saline media

Black soybeans are a food plant commodity that is used as raw material for making soy sauce because it can give a natural black color. This study aims to examine the effect of various doses and times of inoculation of saline-tolerant Rhizobium sp. Inoculum against the production of black soybean (Glycine soja (L) Merrit) on saline media. The research was conducted on 25 September 2019 - 20 February 2020 at the Green House and the Laboratory of Ecology and Plant Production, Faculty of Animal and Agriculture, Diponegoro University, Semarang, Central Java. The study used a completely randomized design with a 4x3 factorial pattern with 3 replications. The first factor is the inoculum dose, namely 0, 5, 10, and 15 mg/plant. The second factor is the time of inoculation, that are at planting, 7 and 14 Days After Sowing (DAS). The results showed that the inoculum dose of 15 mg/plant gave the highest yield on the variables of plant height, number of leaves, weight of seeds and weight of 100 seeds. Inoculum application at planting gave the best results on the variable number of leaves and seed weight. The interaction between dose and time of administration of Rhizobium sp. effect on pod and seeds weight.

Co-expression With Replicating Vector Overcoming Competitive Effects Derived by a Companion Protease Inhibitor in Plants.

Plant-based expression platforms are currently gaining acceptance as a viable alternative for the production of recombinant proteins (RPs), but the degradation of RPs by proteases in cells hinders their superb potentials. Co-expression of a protease inhibitor (PI) shows promise as a strategy to prevent RP from proteolytic degradation in plants. However, competitive effects behind the PI-RP co-expression system may mask or obfuscate the in situ protective effects of a companion PI. Here, we explored the competitive effects by co-expressing reteplase (rPA) with three unrelated PIs, namely NbPR4, HsTIMP, and SlCYS8, in Nicotiana benthamiana leaves. Remarkably, the accumulation of rPA was significantly repressed by each of the three PIs, suggesting that the competitive effects may be common among the PIs. The repression can be attenuated by reducing the PI inoculum dose in the co-inoculation mixtures, showing a negative correlation between the PI abundance of the PI-RP system and competitive effects. Interestingly, when a replicating vector was used to modulate the relative abundance of PI and RP in vivo, rPA was still boosted even at the maximal testing dose of PI, indicating that the competitive effects reduced to an ignorable level by this in vivo approach. Furthermore, a 7- to 12-fold increase of rPA was achieved, proving that it is a useful way for stimulating the potentials of a companion PI by overcoming competitive effects. And, this approach can be applied to molecular farming for improving the RP yields of plant expression systems.

The effect of palm kernel meal (PKM) fermentation by different level and time using Aspergillus Niger to nutrition composition and digestibility on the sensi Agrinak-1 Chicken

The study consisted of two stages; the first stage was to evaluate the chemical nutritional content of palm kernel meal fermented Aspergillus niger then followed by a biological test of the palm kernel meal treatment. The research was conducted using a factorial completely randomized design. The first factor was the dose of Aspergillus niger inoculum: D1 = 4 g/kg DM PKM, D2 = 8 g/kg and D3 = 12 g/kg. The second factor is fermentation time: T1 = fermentation for 3 days, T2 = 6 days and T3 = 9 days. The fermented PKM results were analysed for chemical composition followed by a biological test. The biological test was carried out by placing 30 Sensi Agrinak-1 chickens in individual cages. Chickens were fed palm kernel meal in the first treatment by force feeding as much as 40 g/head. Observation data were tabulated and statistically analysed. The results showed that fermentation of oil palm kernel meal using a dose of Aspergillus niger and different fermentation times could increase the nutrients (chemicals) of palm kernel meal, especially the content of organic matter, besides that it can also increase the digestibility value of dry matter and organic matter in native chickens.

Changes in in-hospital mortality in the first wave of COVID-19: a multicentre prospective observational cohort study using the WHO Clinical Characterisation Protocol UK

SummaryBackgroundMortality rates in hospitalised patients with COVID-19 in the UK appeared to decline during the first wave of the pandemic. We aimed to quantify potential drivers of this change and identify groups of patients who remain at high risk of dying in hospital.MethodsIn this multicentre prospective observational cohort study, the International Severe Acute Respiratory and Emerging Infections Consortium WHO Clinical Characterisation Protocol UK recruited a prospective cohort of patients with COVID-19 admitted to 247 acute hospitals in England, Scotland, and Wales during the first wave of the pandemic (between March 9 and Aug 2, 2020). We included all patients aged 18 years and older with clinical signs and symptoms of COVID-19 or confirmed COVID-19 (by RT-PCR test) from assumed community-acquired infection. We did a three-way decomposition mediation analysis using natural effects models to explore associations between week of admission and in-hospital mortality, adjusting for confounders (demographics, comorbidities, and severity of illness) and quantifying potential mediators (level of respiratory support and steroid treatment). The primary outcome was weekly in-hospital mortality at 28 days, defined as the proportion of patients who had died within 28 days of admission of all patients admitted in the observed week, and it was assessed in all patients with an outcome. This study is registered with the ISRCTN Registry, ISRCTN66726260.FindingsBetween March 9, and Aug 2, 2020, we recruited 80 713 patients, of whom 63 972 were eligible and included in the study. Unadjusted weekly in-hospital mortality declined from 32·3% (95% CI 31·8–32·7) in March 9 to April 26, 2020, to 16·4% (15·0–17·8) in June 15 to Aug 2, 2020. Reductions in mortality were observed in all age groups, in all ethnic groups, for both sexes, and in patients with and without comorbidities. After adjustment, there was a 32% reduction in the risk of mortality per 7-week period (odds ratio [OR] 0·68 [95% CI 0·65–0·71]). The higher proportions of patients with severe disease and comorbidities earlier in the first wave (March and April) than in June and July accounted for 10·2% of this reduction. The use of respiratory support changed during the first wave, with gradually increased use of non-invasive ventilation over the first wave. Changes in respiratory support and use of steroids accounted for 22·2%, OR 0·95 (0·94–0·95) of the reduction in in-hospital mortality.InterpretationThe reduction in in-hospital mortality in patients with COVID-19 during the first wave in the UK was partly accounted for by changes in the case-mix and illness severity. A significant reduction in in-hospital mortality was associated with differences in respiratory support and critical care use, which could partly reflect accrual of clinical knowledge. The remaining improvement in in-hospital mortality is not explained by these factors, and could be associated with changes in community behaviour, inoculum dose, and hospital capacity strain.FundingNational Institute for Health Research and the Medical Research Council.

Microbial bioaugmentation from feces of laying hens in biogas formation on anaerobic coal media

The laying hen livestock industry is growing rapidly, along with the increasing demand for eggs for human consumption, produces large amounts of waste. Improper management of laying hens farm waste can interfere with health and environmental pollution, including greenhouse gases (CH4, CO2, N2O), odor disorders, disturbances from rodent animals, disturbances of endoparasites and ectoparasites, pollution of water and soil sources. Waste management that is correct can reduce the risk of pollution of the laying hen’s industry to the environment by utilizing the feces of laying hens as a source of the microbial consortium that serves as a starter for biogas formation in anaerobic digester as an environmentally friendly alternative energy source. This study aimed to obtain a bacterial and methanogen consortium from feces of laying hens as a starter for biogas formation with coal media in the anaerobic digester. The study used an experimental method of completely randomized design (CRD) with four inoculum doses with four replicates, further tests of orthogonal polynomials. The study was conducted in two stages: the first stage was pretreatment through in-vitro techniques and adaptation process, and the second stage is the addition of the starter of microbial consortium from feces of the laying feces (bioaugmentation) into liquid media and coal at a dose of 0%, 5%, 10% and 15% incubated at 39oC for 28 days. Observations were conducted every seven days from day 0, day 7, day 14, day 21, and day 28. The parameters measured were the volume of biogas, the number of anaerobic bacteria, and the composition of biogas. This biogas composition was analyzed by Gas Chromatography, the number of anaerobic bacteria planted in Hungate tubes, and calculated using the Ogimoto method. The observations showed that the number of bacteria ranging from 1012 CFU/ml up to 1013 CFU/ml exceeded the starter requirements of 107 CFU/ml, which indicated that the microbial consortium obtained met the requirement.

Impact of Seed Applied Rhizobacterial Inoculants on Growth of Wheat (Triticum aestivum) and Cowpea [Vigna unguiculata] and their Influence on Rhizospheric Microbial Diversity

Current study was planned to demonstrate (Experiment I), the impact of seed bacterization (inoculation dose—106, 108, 1010, 1012 CFU/ml) with two bacterial isolates Variovorax paradoxus RAA3 and M11 (Unidentified) on growth and foliar nutrient content (NPK) of wheat (var. H1105 and PBW660) and cowpea (var. PL-1 and PL-2) cultivars under glass house conditions. Strain RAA3 treated plants exhibited most promising results for shoot fresh weight (26.7%, 30.2%), shoot dry weight (44.4%, 63.3%) and chlorophyll content (66.8%, 66.9%) as compared to the control plants of respective varieties. This inoculant also caused significant changes in the foliar nitrogen (14.5%, 14.2%), phosphorus (36.4%, 46.7%) and potassium (20.1%, 65.9%) content in wheat and cowpea, respectively, as compared to the non-inoculated plants. Moreover, the inoculum dose of 108 of bacterial inoculum was found to be most effective and thus, considered as an optimum dose for the plant growth promotion. In another study (Experiment II), seed bacterization with RAA3 (108 CFU/ml) on nine different varieties of wheat was performed, and significant varietal and treatment effect were observed for many of growth parameters as compared to untreated control plants. Overall results showed maximum response at inoculum dose of 108, therefore this dose was taken to assess the influence of PGPR inoculation on rhizospheric microbial diversity of wheat and cowpea. We observed that RAA3 inoculation has led to a shift in microbial population in both wheat and cowpea varieties. Irrespective of varieties, RAA3 (inoculum dose of 108 CFU/ml) treated plants of wheat showed dominant microbial groups of siderophores producers, nitrogen fixers and actinomycetes, whereas, in RAA3 treated plants of cowpea the dominant microbial population of only siderophores producers was recorded.

Dynamic modelling of tetrazolium-based microbial toxicity assay-a parametric proxy of traditional dose-response relationship.

Microbial toxicity of test substances in tetrazolium assay is often quantified while referring to their IC50 values. However, the implication of such an estimate is very limited and can differ across studies depending on prevailing test conditions. In this work, a factorial design-based end-point microbial toxicity assay was performed, which suggests a significant interaction (P= 0.041) between inoculum and tetrazolium dose on formazan production. Subsequently, a dynamic model framework was utilized to capture the nonlinearities in biomass, substrate, formazan profiles and to project the toxicant inhibition parameter as a robust alternative to IC50 value. Microbial growth, glucose uptake and formazan production in the presence or absence of toxicant (Cu2+) from designed batch experiments were used for sequential estimation of model parameters, and their confidence intervals. A logistic growth model with multiplicative inhibition terms for formazan content and toxicant concentration fits the experimental data reasonably well (R2>0.96). Dynamic relative sensitivity analysis revealed that both microbial growth and formazan production profiles were sensitive to toxicant inhibition parameter. The modelling framework not only provides a better insight into the underlying toxic effect but also offers a stable toxicity index for the test substances that can be extended to design a versatile, robust in vitro assay system.

Physico-chemical characteristics of Rhizopus sp.-fermented fish feed pellets containing black soldier fly larvae (Hermetia illucens) meal

In aquaculture, feed cost contributes the highest share in the total production cost. The increase in fishmeal price and the high cost of commercial fish feeds have prompted the search for alternatives. Thus, considerable research has been carried out to develop a farm-made feed that requires simpler methods and cheaper production costs. This study aimed at developing farm-made fish feed using simple equipment, locally available materials, and inexpensive fungal-based bio-floating technique. A combination of using black soldier fly (Hermetia illucens) larvae meal as a fishmeal replacement and Rhizopus sp. fermentation to provide floatability was used. An experiment using three different Rhizopus sp. inoculum doses (1, 2, and 3% w/w) and 3 different fermentation duration (30, 40, and 50 h) were designed, with unfermented feed as control. Results showed that fermented floating feeds gained better nutritional value and physical characteristics (p<0.05). The optimized treatment resulted in a fermented feed with the protein content of 29.72%; fibre 12.13%; fat 26.57%; and ash 7.83%. Relative to the unfermented control, all of the fermentation treatments produced feeds with high average values of floating ability (83.33%) and water stability (92.38).

Evaluation of the Ecological Potential of Microorganisms for Purifying Water with High Iron Content

The ability of a number of microorganisms isolated from highly magnetic soil of the city Mednogorsk to oxidize Fe (II) under conditions of periodic cultivation in a liquid medium was studied. Among the studied microorganisms, two microbial isolates with maximum growth characteristics and iron-oxidizing activity were selected and identified: Bacillus megaterium 69.3 and B. megaterium 69.5. Individual levels of metal resistance of the isolates were determined: maximum tolerated concentration (MTC) for Fe (II) of the isolates B. megaterium 69.3 and B. megaterium 69.5 was 1200 mg L−1, minimum inhibitory concentration (MIC) was 1800 mg L−1. Both microbial isolates actively oxidized Fe (II) by reducing its high concentration in the medium (1.19 g L−1) by 33 and 39% during 14 days of culturing. Total increase in the biomass of B. megaterium 69.3 and B. megaterium 69.5 after 14 days of culturing was 15.3 and 14.7 g L−1; the active parts of the biomass increased 8.7- and 6.9-fold compared to the inoculum dose, respectively. These microbial isolates could be used in future in the biotechnological process of water purification with increased/high levels of Fe (II).