The influence of different concentrations of bio-organic fertilizer on cucumber Fusarium wilt and soil microflora alterations

Microbial response to Nature-Based Solutions in urban soils: A comprehensive analysis using Biolog® EcoPlates™

The study presents a comprehensive examination of changes in soil microbial functional diversity (hereafter called microbial activity) following the implementation of Nature-Based Solutions (NBS) in urban areas. Utilizing the Biolog® EcoPlates™ technique, the study explored variations in microbial diversity in urban soil under NBSs implementation across timespan of two years. Significant differences in microbial activity were observed between control location and those with NBS implementations, with seasonal variations playing a crucial role. NBS positively impacted soil microbial activity especially at two locations: infiltration basin and wild flower meadow showing the most substantial increase after NBS implementation. The study links rainfall levels to microbial functional diversity, highlighting the influence of climatic conditions on soil microbiome. The research investigates also the utilization of different carbon sources by soil microorganisms, shedding light on the specificity of substrate utilization across seasons and locations. The results demonstrate that NBSs implementations lead to changes in substrate utilization patterns, emphasizing the positive influence of NBS on soil microbial communities. Likewise, biodiversity indices, such as Shannon-Weaver diversity (H'), Shannon Evenness Index (E), and substrate richness index (S), exhibit significant variations in response to NBS. Notably, NBS implementation positively impacted H' and E indexes, especially in infiltration basin and wild flower meadow, underlining the benefits of NBS for enhancing microbial diversity. The obtained results demonstrated valuable insight into the dynamic interactions between NBS implementation and soil microbial activity. The findings underscore the potential of NBS to positively influence soil microbial diversity in urban environments, contributing to urban sustainability and soil health. The study emphasizes the importance of monitoring soil microbial activity to assess the effectiveness of NBS interventions and guides sustainable urban development practices.

Co-Culture of White Rot Fungi Pleurotus ostreatus P5 and Bacillus amyloliquefaciens B2: A Strategy to Enhance Lipopeptide Production and Suppress of Fusarium Wilt of Cucumber

Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (FOC), poses a serious threat to cucumber productivity. Compared to traditional chemical pesticides, biological control strategies have attracted more attention recently owing to their effectiveness against pathogens and their environmental safety. This study investigated the effect of white rot fungi Pleurotus ostreatus P5 on the production of cyclic lipopeptides (CLPs) of Bacillus amyloliquefaciens B2 and the potential co-culture filtrate of strains B2 and P5 to control cucumber Fusarium wilt. A PCR amplification of CLP genes revealed that B. amyloliquefaciens B2 had two antibiotic biosynthesis genes, namely, ituA and srf, which are involved in iturin A and surfactin synthesis. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) revealed that CLPs derived from strain B2 contained two families, iturin A (C14, C15) and surfactin (C12-C17). The co-culture exhibited an enhanced accumulation of iturin A and surfactin compared to the monoculture of strain B2. Furthermore, the gene expressions of ituA and srf were both significantly upregulated when co-cultured with the fungus compared to monocultures. In an in vitro experiment, the co-culture filtrate and monoculture filtrate of B. amyloliquefaciens B2 inhibited mycelial growth by 48.2% and 33.2%, respectively. In a greenhouse experiment, the co-culture filtrate was superior to the monoculture filtrate in controlling cucumber Fusarium wilt disease and in the promotion of plant growth. Co-culture filtrate treatment significantly enhanced the microbial metabolic activity and decreased the abundance of FOC in the rhizosphere soil. These results show that the co-culture of P. ostreatus P5 and B. amyloliquefaciens B2 has great potential in cucumber Fusarium wilt disease prevention by enhancing the production of bacterial CLPs.

Effects of nitrogen reduction combined with bio-organic fertilizer on soil bacterial community diversity of red raspberry orchard

Understanding soil bacterial diversity under nitrogen reduction is necessary for the crucial role in soil nitrogen cycling. However, the effects of combined fertilization on soil chemical properties, microbial community structure, and yield are unknown. This study was conducted to investigate the effect of nitrogen fertilizer reduction with bio-organic fertilizer on soil bacterial community diversity of red raspberry orchard. Six treatments were set in this study: NF-100%, NF-75%, NF-50%, NF-25% and CF, no nitrogen fertilizer and bio-organic fertilizer for CK. The bacterial community structures of soil were analyzed by 16S rRNA gene amplification high-throughput sequencing technology. Nitrogen fertilizer reduction with bio-organic fertilizer increased soil organic matter (SOM), total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), available potassium (AK), and reduced soil pH. NF-50% and NF-25% treatments increased the yield of red raspberry. Nitrogen reduction combined with bio-organic fertilizer increased the relative abundance of copiotrophic bacteria and decreased the relative abundance of oligotrophic bacteria. The increase in copiotrophic bacteria in the soil of red raspberry orchard could indicate an increase in soil nutrient availability, which have positive implications for soil fertility and production. However, nitrogen fertilizer reduction with bio-organic fertilizer altered the abundance and diversity of soil bacteria, which was reduced compared to CF treatments. The PCoA analysis of the soil bacterial community showed that the community structure of NF-25% treatment was more different from other treatments, indicating that the fertilization method changed the community structure of soil bacteria. The results of a redundancy analysis showed that SOM, pH, AN, TN, and AP were the main factors affecting the microbial community structure. Overall, the reduction of nitrogen fertilizer with bio-organic fertilizer significantly increased the soil nutrient content, reduced the relative abundance and diversity of soil bacteria, increased the relative abundance of beneficial bacteria in the soil, changed the bacterial community structure of soil, increased production and created suitable soil conditions for the red raspberry growth.

Effect of long-term application of bioorganic fertilizer on the soil property and bacteria in rice paddy

The application of novel bioorganic fertilizer (BIO) has been established as a weed biocontrol strategy, and reduce herbicides pollution and negatively effects on agricultural ecosystems. However, its long-term influences on soil bacterial communities are unknown. Here, 16 S rRNA sequencing to identify the changes that occur in soil bacterial community and enzyme under BIO treatments after five years in a field experiment. BIO application effectively controlled weeds, however no obvious differences between treatments were observed under BIO-50, BIO-100, BIO-200 and BIO-400 treatment. Anaeromyxobacter and Clostridium_ sensu_ stricto_1 were the two dominant genera among BIO-treated soil samples. The BIO-800 treatment had a slight influence on the species diversity index, which was more remarkable after five years. The seven significantly-different genera between BIO-800 treatment and untreated soils included C._sensu_stricto_1, Syntrophorhabdus, Candidatus_Koribacter, Rhodanobacter, Bryobacter, Haliangium, Anaeromyxobacter. In addition, BIO application had different effects on soil enzymatic activities and chemical properties. The extractable P and pH saliency correlated with Haliangium and C._Koribacter, and C._sensu_stricto_1 observably correlated with exchangeable K, hydrolytic N and organic matter. Taken together, our data suggest that BIO application effectively controlled weeds and a slight influence on soil bacterial communities and enzymes. These findings expand our knowledge of the application of BIO as widely used as a sustainable weed control in rice paddy.

Application of Sophora alopecuroides organic fertilizer changes the rhizosphere microbial community structure of melon plants and increases the fruit sugar content

BACKGROUND

Sophora alopecuroides L. is a leguminous plant commonly found in northwest China. In Xinjiang, the fresh herb of S. alopecuroides is often applied as a green fertilizer to the rhizosphere of melon (Cucumis melo) plants at the end of their flowering period, to improve the taste of the fruits. However, the effects of S. alopecuroides-based fertilizers on the microbial community structure of soil and crop-root systems are unclear. In order to study the sweetening mechanism of the S. alopecuroides organic fertilizer, three different varieties of melon were selected. The untreated plants were used as the control (CK) group, and the plants treated with S. alopecuroides-based organic fertilizer were selected as the treatment (T) group. The physical and chemical properties, enzyme activities and microbial community structure of the rhizosphere samples were also determined, and a correlation analysis with the fruit sweetness index was conducted.

RESULTS

Sugar content of group T was at least 40% higher than that of group CK. The increase in fruit sugar content positively correlated with the increase in the abundance of beneficial microorganisms, including Pseudomonas, Bacillus, Mycobacterium, Burkholderia, Streptomyces, Acinetobacter, Proteobacteria, Lysobacter, Actinomycetes, Penicillium and Aspergillus.

CONCLUSION

Sophora alopecuroides organic fertilizer could alter the composition and function of bacterial and fungal communities and promote the growth of beneficial bacteria in the melon plant rhizosphere. Further, it could increase the content of soluble solids and sugar in the fruits to achieve a sweetening effect. This fertilizer can be applied as a fruit sweetener in melon cultivation, improving the sugar content of the fruit and consequently the sweetness. © 2022 Society of Chemical Industry.

Dynamic analysis of the microbial communities and metabolome of healthy banana rhizosphere soil during one growth cycle

Background

The banana-growing rhizosphere soil ecosystem is very complex and consists of an entangled network of interactions between banana plants, microbes and soil, so identifying key components in banana production is difficult. Most of the previous studies on these interactions ignore the role of the banana plant. At present, there is no research on the the micro-ecological environment of the banana planting growth cycle.

Methods

Based on high-throughput sequencing technology and metabolomics technology, this study analyzed the rhizosphere soil microbial community and metabolic dynamics of healthy banana plants during one growth cycle.

Results

Assessing the microbial community composition of healthy banana rhizosphere soil, we found that the bacteria with the highest levels were Proteobacteria, Chloroflexi, and Acidobacteria, and the dominant fungi were Ascomycota, Basidiomycota, and Mortierellomycota. The metabolite profile of healthy banana rhizosphere soil showed that sugars, lipids and organic acids were the most abundant, accounting for about 50% of the total metabolites. The correlation network between fungi and metabolites was more complex than that of bacteria and metabolites. In a soil environment with acidic pH, bacterial genera showed a significant negative correlation with pH value, while fungal genera showed no significant negative correlation with pH value. The network interactions between bacteria, between fungi, and between bacteria and fungi were all positively correlated.

Conclusions

Healthy banana rhizosphere soil not only has a stable micro-ecology, but also has stable metabolic characteristics. The microorganisms in healthy banana rhizosphere soil have mutually beneficial rather than competitive relationships.

Application and Development of Biocontrol Agents in China

While the growing population in the world has a large demand for food, agriculture and forestry are currently facing severe challenges due to phytopathogens and pests along with global warming. For half a century chemical pesticides and fertilizers have made a great contribution to agricultural production. However, the excessive use of chemical agents has caused obvious side effects on the environment and the sustainable development of agriculture in the long term. China has recorded one of the fastest economic growths for more than 20 years but at the cost of a seriously polluted environment. Since a decade ago, China has paid increasing attention to environment protection and taken intensified measures for pollution control and ecological restoration. In this context, the biocontrol agent industry in China has experienced a golden decade of rapid development. In this minireview, we will introduce the application and development of microorganism-based biocontrol agents in China over the past two decades.

Taxonomic and Functional Diversity of Rhizosphere Microbiome Recruited From Compost Synergistically Determined by Plant Species and Compost

Compost is frequently served as the first reservoir for plants to recruit rhizosphere microbiome when used as growing substrate in the seedling nursery. In the present study, recruitment of rhizosphere microbiome from two composts by tomato, pepper, or maize was addressed by shotgun metagenomics and 16S rRNA amplicon sequencing. The 16S rRNA amplicon sequencing analysis showed that 41% of variation in the rhizosphere bacterial community was explained by compost, in contrast to 23% by plant species. Proteobacterial genera were commonly recruited by all three plant species with specific selections for Ralstonia by tomato and Enterobacteria by maize. These findings were confirmed by analysis of 16S rRNA retrieved from the shotgun metagenomics library. Approximately 70% of functional gene clusters differed more than sevenfold in abundance between rhizosphere and compost. Functional groups associated with the sensing and up-taking of C3 and C4 carboxylic acids, amino acids, monosaccharide, production of antimicrobial substances, and antibiotic resistance were over-represented in the rhizosphere. In summary, compost and plant species synergistically shaped the composition of the rhizosphere microbiome and selected for functional traits associated with the competition on root exudates.

Influence of lead on the activity of soil microorganisms in two Beskidy landscape parks

The aim of the study was to assess the potential impact of lead on soil metabolism in two landscape parks localized in the Beskid Śląski and Beskid Żywiecki mountains which were affected, among others, by air pollution from the Upper Silesian Industrial Region, the largest industrial zone in Poland. The study was carried out in six locations with different lead levels in the soil environment. Each plot was equipped with four pairs of vacuum ceramic lysimeters to assess the mobility of Pb in the soil. The metabolic activity was assessed by measuring: soil enzyme activity, soil respiration and by studying community-level physiological profiling (CLPP) using Biolog EcoPlates technique. The soil to the examination was collected near the stands with the lysimeters from two soil horizons (A and B layer). The analyses carried out showed that the factors that had the greatest influence on lead mobility were the organic carbon content and the soil pH. The elevated lead level in the topsoil (layer A) could affect the functional biodiversity of soil microorganisms, but low soil pH was a more likely limiting factor. In the subsoil (layer B), lower lead content was found and its probable effect on soil microbial activity was small. In summary, it can be concluded that the assessment of the influence of heavy metals on soil metabolism is not easy, and the Biolog system has proven to be a sensitive tool for assessing the potential impact of heavy metals on the soil environment.

Effect of Two Kinds of Fertilizers on Growth and Rhizosphere Soil Properties of Bayberry with Decline Disease

Decline disease causes severe damage to bayberry. However, the cause of this disease remains unclear. Interestingly, our previous studies found that the disease severity is related with the level of soil fertilizer. This study aims to explore the effect and mechanism of compound fertilizer (CF) and bio-organic fertilizer (OF) in this disease by investigating the vegetative growth, fruit characters, soil property, rhizosphere microflora and metabolites. Results indicated that compared with the disease control, CF and OF exhibited differential effect in plant healthy and soil quality, together with the increase in relative abundance of Burkholderia and Mortierella, and the reduction in that of Rhizomicrobium and Acidibacter, Trichoderma, and Cladophialophora reduced. The relative abundance of Geminibasidium were increased by CF (251.79%) but reduced by OF (13.99%). In general, the composition of bacterial and fungal communities in rhizosphere soil was affected significantly at genus level by exchangeable calcium, available phosphorus, and exchangeable magnesium, while the former two variables had a greater influence in bacterial communities than fungal communities. Analysis of GC-MS metabonomics indicated that compared to the disease control, CF and OF significantly changed the contents of 31 and 45 metabolites, respectively, while both fertilizers changed C5-branched dibasic acid, galactose, and pyrimidine metabolic pathway. Furthermore, a significant correlation was observed at the phylum, order and genus levels between microbial groups and secondary metabolites of bayberry rhizosphere soil. In summary, the results provide a new way for rejuvenation of this diseased bayberry trees.

The Damage Caused by Decline Disease in Bayberry Plants through Changes in Soil Properties, Rhizosphere Microbial Community Structure and Metabolites

Decline disease causes serious damage and rapid death in bayberry, an important fruit tree in south China, but the cause of this disease remains unclear. The aim of this study was to investigate soil quality, microbial community structure and metabolites of rhizosphere soil samples from healthy and diseased trees. The results revealed a significant difference between healthy and diseased bayberry in soil properties, microbial community structure and metabolites. Indeed, the decline disease caused a 78.24% and 78.98% increase in Rhizomicrobium and Cladophialophora, but a 28.60%, 57.18%, 38.84% and 68.25% reduction in Acidothermus, Mortierella, Trichoderma and Geminibasidium, respectively, compared with healthy trees, based on 16S and ITS amplicon sequencing of soil microflora. Furthermore, redundancy discriminant analysis of microbial communities and soil properties indicated that the main variables of bacterial and fungal communities included pH, organic matter, magnesium, available phosphorus, nitrogen and calcium, which exhibited a greater influence in bacterial communities than in fungal communities. In addition, there was a high correlation between the changes in microbial community structure and secondary metabolites. Indeed, GC-MS metabolomics analysis showed that the healthy and diseased samples differed over six metabolic pathways, including thiamine metabolism, phenylalanine-tyrosine-tryptophan biosynthesis, valine-leucine-isoleucine biosynthesis, phenylalanine metabolism, fatty acid biosynthesis and fatty acid metabolism, where the diseased samples showed a 234.67% and 1007.80% increase in palatinitol and cytidine, respectively, and a 17.37-8.74% reduction in the other 40 metabolites compared to the healthy samples. Overall, these results revealed significant changes caused by decline disease in the chemical properties, microbiota and secondary metabolites of the rhizosphere soils, which provide new insights for understanding the cause of this bayberry disease.

The microbial community in a green turtle nesting beach in the Mediterranean: application of the Biolog EcoPlate approach for beach pollution

This study aims to characterize the microbial community and its relationship with heavy metal pollution in the beaches of Sugözü, an important nesting site for the green turtle. Heavy metal concentrations of sand samples from subregions of Sugözü were determined using ICP-MS. The microbial community was analyzed using the Biolog® EcoPlate. The relationship between microbial catalytic activity and heavy metal levels were analyzed using canonical correspondence analysis. Levels of ²⁷Al, ⁵⁷Fe, ⁵⁵Mn, and ⁵²Cr were quite high (4332.34, 13,764.77, 590.98, and 48.21 mg/kg, respectively). The microbial community in subregions with high levels of metals was found to use carboxylic acid as a carbon source. Bioactivity, substrate utilization, diversity, and evenness values indicated negative correlations concentrations of ²⁷Al, ⁵⁶Fe, and ⁵²Cr (-0.820, -0.508, and -0.560, respectively). It was also found that microbial diversity decreased in the subregions where heavy metal concentration increased. Embryonic deaths were found highest at early stage (0.1 to 0.2 eggs) and lowest at middle stage for whole study sites by inspecting a total 6408 eggs of 63 green turtle nests. The Biolog EcoPlate was firstly applied to determine pollution, and our findings clearly demonstrate the applicability and effectiveness of this method in assessing nesting beaches.

Effects of Different Continuous Cropping Years on Bacterial Community and Diversity of Cucumber Rhizosphere Soil in Solar-Greenhouse

The rhizosphere soils from 1, 3, 5, and 7 years of cucumber continuous cropping in solar-greenhouse were used as the research objects. The region of bacterial 16S rRNA was analyzed by Illumina MiSeq high-throughput sequencing technology. The effect of continuous cropping years on the microbial community structure and diversity in cucumber soil in the greenhouse was investigated. The physical and chemical properties of soil and the activities of urease and catalase were determined. The results showed that cucumber crop succession for different years affected the community composition of the bacteria at the phylum level, and the abundance of Proteobacteria, Chloroflexi, Gemmatimonadetes, Patescibacteria and Firmicutes gradually increased, while Actinobacteria in the soil significantly decreased. Among the top 15 significantly different genera, with the extension of successive years, the relative abundance of most genera in bacteria decreased after a small increase in year 3. The diversity results indicated that soil samples from continuous cropping for 7 years had the lowest community diversity. PICRUSt analysis showed a decreasing trend in soil bacterial function as the cucumber crop succession age increased. In environmental factor clustering analysis, the soil bacterial community was significantly correlated with pH, available nitrogen (AN), soil urease (SUR) and available phosphorus (AP), and the effect on the bacterial community was expressed as SUR > AP > AN > pH.

Remediation and improvement of 2,4-dichlorophenol contaminated soil by biochar-immobilized laccase

In this paper, laccase was immobilized with the adsorption-crosslinking method in which biochar was used as the carrier and glutaraldehyde was used as the crosslinking agent. Firstly, the optimal immobilization conditions and optimal operating conditions were investigated, and then the stability of both free laccase and immobilized laccase was compared. Finally, the 2,4-dichlorophenol contaminated soil was remedied with both free laccase and immobilized laccase, and the improvement on the remediation of the contaminated soil by immobilized laccase was analysed through the ecological evaluation. The results showed that in the optimal immobilization condition, the biochar with a particle size of 30 mesh should be selected, and glutaraldehyde with a volume fraction of 4% and 20 mL of laccase solution should be added to complete the 6-hour adsorption operation and 4-hour crosslinking operation. The stability of immobilized laccase was better than that of free laccase, and the thermal deactivation kinetic equation for the free laccase was lnA = -0.7657t + 0.4344 and the thermal deactivation kinetic equation for the immobilized laccase was lnA = -0.1048t + 0.0608, respectively. The degradation ability of immobilized laccase for 2-4 dichlorophenol was better than that of free laccase. The degradation rate of 2,4-dichlorophenol was 44.4% in the free laccase group and 64.6% in the immobilized laccase group. The ecological evaluation showed that the biochar-immobilized laccase had a positive effect on the soil ecological environment in the remediation process of the soil and can improve the remediation of the contaminated soil to some extent.

First reported quantitative microbiota in different livestock manures used as organic fertilizers in the Northeast of Thailand

Northeastern Thailand relies on agriculture as a major economic activity, and has used high levels of agrochemicals due to low facility, and salty sandy soil. To support soil recovery and sustainable agriculture, local farmers have used organic fertilizers from farmed animal feces. However, knowledge about these animal fecal manures remains minimal restricting their optimal use. Specifically, while bacteria are important for soil and plant growth, an abundance and a diversity of bacterial composition in these animal fecal manures have not been reported to allow selection and adjustment for a more effective organic fertilizer. This study thereby utilized metagenomics combined with 16S rRNA gene quantitative PCR (qPCR) and sequencing to analyze quantitative microbiota profiles in association with nutrients (N, P, K), organic matters, and the other physiochemical properties, of the commonly used earthworm manure and other manures from livestock animals (including breed and feeding diet variations) in the region. Unlike the other manures, the earthworm manure demonstrated more favorable nutrient profiles and physiochemical properties for forming fertile soil. Despite low total microbial biomass, the microbiota were enriched with maximal OTUs and Chao richness, and no plant pathogenic bacteria were found based on the VFDB database. The microbial metabolic potentials supported functions to promote crop growth, such as C, N and P cyclings, xenobiotic degradation, and synthesis of bioactive compounds. Pearson's correlation analyses indicated that the quantitative microbiota of the earthworm manure were clustered in the same direction as N, and conductivity, salinity, and water content were essential to control the microbiota of animal manures.

The Soil Nutrient Environment Determines the Strategy by Which Bacillus velezensis HN03 Suppresses Fusarium wilt in Banana Plants

Biological control agents (BCAs) are considered as one of the most important strategies for controlling Fusarium wilt, and bioorganic fertilizer, in particular, has been extensively investigated. However, little is known regarding how a biocontrol microorganism affects the suppression mechanisms when combined with different amendments. In this study, a pot experiment was performed using banana plants to investigate the different mechanisms by which the biocontrol bacterium Bacillus velezensis HN03 (isolated from our laboratory) and amendments suppress Fusarium wilt. The incidence of banana wilt was decreased under HN03 and was reduced further when HN03 was combined with compost, particularly wormcast. In the suppression of Fusarium wilt, HN03 was found to influence the soil environment in various ways. HN03 increased the peroxidase level, which improves plant defense, and was highest when combined with wormcast, being 69 times higher than when combined with cow dung compost. The high accumulation of Mg and P in the "HN03 + wormcast" and Zn and Mn in the "HN03 + cow dung" treatments was negatively correlated with disease incidence. Furthermore, HN03 re-established the microbial community destroyed by the pathogen and further increased the level of suppression in the wormcast. HN03 also enhanced the functional traits of the soil, including defensive mechanism-related traits, and these traits were further enhanced by the combination of HN03 + wormcast.

Diversity and spoilage potential of microbial communities associated with grape sour rot in eastern coastal areas of China

As a polymicrobial disease, sour rot decreases grape berry yield and wine quality. The diversity of microbial communities in sour rot-affected grapes depends on the cultivation site, but the microbes responsible for this disease in eastern coastal China, has not been reported. To identify the microbes that cause sour grape rot in this important grape-producing region, the diversity and abundance of bacteria and fungi were assessed by metagenomic analysis and cultivation-dependent techniques. A total of 15 bacteria and 10 fungi were isolated from sour rot-affected grapes. High-throughput sequencing of PCR-amplicons generated from diseased grapes revealed 1343 OTUs of bacteria and 1038 OTUs of fungi. Proteobacteria and Firmicutes were dominant phyla among the 19 bacterial phyla identified. Ascomycota was the dominant fungal phylum and the fungi Issatchenkia terricola, Colletotrichum viniferum, Hanseniaspora vineae, Saprochaete gigas, and Candida diversa represented the vast majority ofmicrobial species associated with sour rot-affected grapes. An in vitro spoilage assay confirmed that four of the isolated bacteria strains (two Cronobacter species, Serratia marcescens and Lysinibacillus fusiformis) and five of the isolated fungi strains (three Aspergillus species, Alternaria tenuissima, and Fusarium proliferatum) spoiled grapes. These microorganisms, which appear responsible for spoiling grapes in eastern China, appear closely related to microbes that cause this plant disease around the world.

Animal wastes as fertilizers enhance growth of young walnut trees under soil drought conditions

BACKGROUND

Using nutrient-rich animal wastes as organic fertilizers in agricultural practices is a sustainable method for soil amendment and avoiding environmental pollution. In order to evaluate their practical effect, we applied different proportions of animal waste as fertilizers to wet or dry soils that were either planted or not planted with young walnut trees.

RESULTS

The results showed that animal waste could increase soil C accumulation and carbon to nitrogen (C/N) ratio and reduce soil organic nitrogen and total nitrogen contents as well as the nitrogen to phosphorus (N/P) ratio in the planted group soil. This framework of soil C and N composition (a high C/N ratio) resulted in high N and Mg contents as well as high Cu and Zn contents in the leaves of the young trees as well as a high dry matter weight/leaf N ratio, causing increased leaf photosynthesis, reduced transpiration and relatively high water use efficiency under soil drought conditions. Also, animal wastes as fertilizers caused the branching of walnut to switch from elongation growth to thickening growth under soil drought conditions.

CONCLUSIONS

Principal component analysis and redundancy analysis demonstrated the mechanism by which the soil C/N ratio mediates the flux of available nutrients from the soil to the plant and thereby regulates plant dry matter accumulation and branching architecture under soil drought conditions. The results of this study provide new insights into the improvement of hilly soils using animal waste. © 2020 Society of Chemical Industry.

Deciphering microbial diversity associated with Fusarium wilt-diseased and disease-free banana rhizosphere soil

Background

Fusarium wilt of banana (Musa spp.) caused by the fungal pathogen Fusarium oxysporum f. sp. cubense (Foc) is a typical soilborne disease, that severely devastates the banana industry worldwide, and soil microbial diversity is closely related to the spread of Fusarium wilt. To understand the relationship between microbial species and Fusarium wilt, it is important to understand the microbial diversity of the Fusarium wilt-diseased and disease-free soils from banana fields.

Results

Based on sequencing analysis of the bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) sequences, Foc abundance, fungal or bacterial richness and diversity were higher in the diseased soils than in the disease-free soils. Although Ascomycota and Zygomycota were the most abundant fungi phyla in all soil samples, Ascomycota abundance was significantly reduced in the disease-free soils. Mortierella (36.64%) was predominant in the disease-free soils. Regarding bacterial phyla, Proteobacteria, Acidobacteria, Chloroflexi, Firmicutes, Actinobacteria, Gemmatimonadetes, Bacteroidetes, Nitrospirae, Verrucomicrobia and Planctomycetes were dominant phyla in all soil samples. In particular, Firmicutes contributed 16.20% of the total abundance of disease-free soils. At the bacterial genus level, Bacillus, Lactococcus and Pseudomonas were abundant in disease-free soils with abundances of 8.20, 5.81 and 2.71%, respectively; lower abundances, of 4.12, 2.35 and 1.36%, respectively, were found in diseased soils. The distribution characteristics of fungal and bacterial genera may contribute to the abundance decrease of Foc in the disease-free soils.

Conclusion

Unique distributions of bacteria and fungi were observed in the diseased and disease-free soil samples from banana fields. These specific genera are useful for constructing a healthy microbial community structure of soil.

Long-Term Plastic Greenhouse Cultivation Changes Soil Microbial Community Structures: A Case Study

Plastic greenhouse vegetable cultivation (PGVC) has been widely developed around the world and has resulted in great changes in soil properties and potential contamination by phthalate esters (PAEs). Using high-throughput sequencing, this study investigated the succession and potential factors impacting soil microbial community structures over 20 years of PGVC. The results showed that the pH of soils under PGVC were significantly lower, while the nutrient contents of soils were higher, relative to those of open field soil. The residue concentrations of PAEs in soil under PGVC increased with increasing periods of PGVC. The fungal community diversity, rather than the bacterial community diversity, was significantly reduced in soils under PGVC. However, both the soil bacterial and fungal community structures were changed by long-term PGVC. Among the tested soil physicochemical properties, soil pH and clay were the top two factors affecting the soil bacterial community, while pH and phosphorus (P) mainly affected the soil fungal community structures. No relationship between the changes of microbial communities and PAE residues in soil was observed. This study indicates that the soil acidification and nutrient accumulation under PGVC mainly shifted the changes of soil microbial community structures, which could occur after only 5 years of PGVC.

Influence of red mud on soil microbial communities: Application and comprehensive evaluation of the Biolog EcoPlate approach as a tool in soil microbiological studies

Red mud can be applied as soil ameliorant to acidic, sandy and micronutrient deficient soils. There are still knowledge gaps regarding the effects of red mud on the soil microbial community. The Biolog EcoPlate technique is a promising tool for community level physiological profiling. This study presents a detailed evaluation of Biolog EcoPlate data from two case studies. In experiment "A" red mud from Ajka (Hungary) was mixed into acidic sandy soil in soil microcosms at 5-50 w/w%. In experiement "B" red mud soil mixture was mixed into low quality subsoil in a field experiment at 5-50 w/w%. According to average well color development, substrate average well color development and substrate richness 5-20% red mud increased the microbial activity of the acidic sandy soil over the short term, but the effect did not last for 10months. Shannon diversity index showed that red mud at up to 20% did not change microbial diversity over the short term, but the diversity decreased by the 10th month. 30-50% red mud had deteriorating effect on the soil microflora. 5-20% red mud soil mixture in the low quality subsoil had a long lasting enhancing effect on the microbial community based on all Biolog EcoPlate parameters. However, 50% red mud soil mixture caused a decrease in diversity and substrate richness. With the Biolog EcoPlate we were able to monitor the changes of the microbial community in red mud affected soils and to assess the amount of red mud and red mud soil mixture applicable for soil treatment in these cases.