scholarly journals Biocontrol of Two Bacterial Inoculant Strains and Their Effects on the Rhizosphere Microbial Community of Field-Grown Wheat

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xiaohui Wang ◽  
Chao Ji ◽  
Xin Song ◽  
Zhaoyang Liu ◽  
Yue Liu ◽  
...  

Biocontrol by inoculation with beneficial microbes is a proven strategy for reducing the negative effect of soil-borne pathogens. We evaluated the effects of microbial inoculants BIO-1 and BIO-2 in reducing soil-borne wheat diseases and in influencing wheat rhizosphere microbial community composition in a plot test. The experimental design consisted of three treatments: (1) Fusarium graminearum F0609 (CK), (2) F. graminearum + BIO-1 (T1), and (3) F. graminearum F0609 + BIO-2 (T2). The results of the wheat disease investigation showed that the relative efficacies of BIO-1 and BIO-2 were up to 82.5% and 83.9%, respectively. Illumina MiSeq sequencing revealed that bacterial abundance and diversity were significantly higher ( P < 0.05 ) in the treatment groups (T1 and T2) than in the control, with significantly decreased fungal diversity in the T2 group. Principal coordinates and hierarchical clustering analyses revealed that the bacterial and fungal communities were distinctly separated between the treatment and control groups. Bacterial community composition analysis demonstrated that beneficial microbes, such as Sphingomonas, Bacillus, Nocardioides, Rhizobium, Streptomyces, Pseudomonas, and Microbacterium, were more abundant in the treatment groups than in the control group. Fungal community composition analysis revealed that the relative abundance of the phytopathogenic fungi Fusarium and Gibberella decreased and that the well-known beneficial fungi Chaetomium, Penicillium, and Humicola were more abundant in the treatment groups than in the control group. Overall, these results confirm that beneficial microbes accumulate more easily in the wheat rhizosphere following application of BIO-1 and BIO-2 and that the relative abundance of phytopathogenic fungi decreased compared with that in the control group.

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Jian-Ping Liang ◽  
Zhi-Quan Xue ◽  
Zhen-Yu Yang ◽  
Zhi Chai ◽  
Jing-Ping Niu ◽  
...  

Abstract Purpose The application of excessive chemical fertilizers during the cultivation of Astragalus membranaceus leads to a decline in the quality of this medicinal plant as well as the soil’s sustainable productivity. In this study, we developed a special microbial organic fertilizer for A. membranaceus and investigated its effects on plant growth and rhizosphere microbial communities. Methods The root biomass and main active components of A. membranaceus in different growth stages were measured to assess the impacts of microbial organic manure on plant growth. Meanwhile, 16S rRNA and ITS1 amplicons were amplified and high-throughput sequencing was performed to detect the dynamic impacts of microbial organic manure on rhizosphere microbial communities. Result The results demonstrated that microbial organic manure significantly increased wet and dry weights of A. membranaceus seedlings and the accumulation of two effective components (flavonoids and saponin) in bacterial fertilizer treatment groups are significant higher than the control group. Research on rhizosphere microbial flora shows that the number and polymorphism of bacteria and fungi were decreased after the application of special fertilizer during the rapid growth period of plant and then gradually increased with seedling growth. The community structure of bacteria was regulated after the application of special fertilizer, and the beneficial bacteria for plant growth are enriched. Functional profiles prediction showed that significant shifts in metabolic functions impacting KEGG pathways of the microbial fertilizer treatment groups are related to metabolism and biosynthesis. Conclusion The results indicate that the microbial organic manure can improve A. membranaceus growth by providing appropriate nutrients and regulating the rhizosphere microbial community which has good potential in ecological cultivation of A. membranaceus.


2020 ◽  
Vol 8 (9) ◽  
pp. 1325
Author(s):  
Junhui Li ◽  
Joshua Philp ◽  
Jishun Li ◽  
Yanli Wei ◽  
Hongmei Li ◽  
...  

Clubroot is a disease of cruciferous crops that causes significant economic losses to vegetable production worldwide. We applied high-throughput amplicon sequencing technology to quantify the effect of Trichodermaharzianum LTR-2 inoculation on the rhizosphere community of Chinese cabbage (Brassica rapa subsp. pekinensis cv. Jiaozhou) in a commercial production area. T. harzianum inoculation of cabbage reduced the incidence of clubroot disease by 45.4% (p < 0.05). The disease control efficacy (PDIDS) was 63%. This reduction in disease incidence and severity coincided with a drastic reduction in both the relative abundance of Plasmodiaphora brassicae, the causative pathogen of cabbage clubroot disease, and its copy number in rhizosphere soil. Pathogenic fungi Alternaria and Fusarium were also negatively associated with Trichoderma inoculation according to co-occurrence network analysis. Inoculation drastically reduced the relative abundance of the dominant bacterial genera Delftia and Pseudomonas, whilst increasing others including Bacillus. Our results demonstrate that T. harzianum LTR-2 is an effective biological control agent for cabbage clubroot, which acts through modulation of the soil and rhizosphere microbial community.


2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 293-294
Author(s):  
Camila S Marcolla ◽  
Benjamin Willing

Abstract This study aimed to characterize poultry microbiota composition in commercial farms using 16S rRNA sequencing. Animals raised in sanitized environments have lower survival rates when facing pathogenic challenges compared to animals naturally exposed to commensal organisms. We hypothesized that intensive rearing practices inadvertently impair chicken exposure to microbes and the establishment of a balanced gut microbiota. We compared gut microbiota composition of broilers (n = 78) and layers (n = 20) from different systems, including commercial intensive farms with and without in-feed antibiotics, organic free-range farms, backyard-raised chickens and chickens in an experimental farm. Microbial community composition of conventionally raised broilers was significantly different from antibiotic-free broilers (P = 0.012), from broilers raised outdoors (P = 0.048) and in an experimental farm (P = 0.006) (Fig1). Significant community composition differences were observed between antibiotic-fed and antibiotic-free chickens (Fig2). Antibiotic-free chickens presented higher alpha-diversity, higher relative abundance of Deferribacteres, Fusobacteria, Bacteroidetes and Actinobacteria, and lower relative abundance of Firmicutes, Clostridiales and Enterobacteriales than antibiotic-fed chickens (P &lt; 0.001) (Fig3). Microbial community composition significantly changed as birds aged. In experimental farm, microbial community composition was significant different for 7, 21 and 35 day old broilers (P &lt; 0.001), and alpha diversity increased from 7 to 21d (P &lt; 0.024), but not from 21 to 35d; whereas, in organic systems, increases in alpha-diversity were observed from 7d to 21d, and from 21d to 35d (P &lt; 0.05). Broilers and layers raised together showed no differences in microbiota composition and alpha diversity (P &gt; 0.8). It is concluded that production practices consistently impact microbial composition, and that antibiotics significantly reduces microbial diversity. We are now exploring the impact of differential colonization in a controlled setting, to determine the impact of the microbes associated with extensively raised chickens. This study will support future research and the development of methods to isolate and introduce beneficial microbes to commercial systems.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vanessa L. Brisson ◽  
Jennifer E. Schmidt ◽  
Trent R. Northen ◽  
John P. Vogel ◽  
Amélie C. M. Gaudin

Abstract Maize domestication and breeding have resulted in drastic and well documented changes in aboveground traits, but belowground effects on root system functioning and rhizosphere microbial communities remain poorly understood, despite their critical importance for nutrient and water acquisition. We investigated the rhizosphere microbial community composition and structure of ten Zea mays accessions along an evolutionary transect (two teosinte, three inbred maize lines, and five modern maize hybrids) grown in nutrient depleted soil from a low input agricultural system. Microbial community analysis revealed significant differences in community composition between soil compartments (proximal vs. distal rhizosphere) and between plant genetic groups (teosinte, inbred, and modern hybrid). Only a small portion of the microbial community was differentially selected across plant genetic groups: 3.7% of prokaryotic community members and 4.9% of fungal community members were significantly associated with a specific plant genetic group. Indicator species analysis showed the greatest differentiation between modern hybrids and the other two plant genetic groups. Co-occurrence network analysis revealed that microbial co-occurrence patterns of the inbred maize lines’ rhizosphere were significantly more similar to those of the teosintes than to the modern hybrids. Our results suggest that advances in hybrid development significantly impacted rhizosphere microbial communities and network assembly.


2021 ◽  
Vol 8 ◽  
Author(s):  
Hongxia Zhang ◽  
Mingshan Song ◽  
Lili Wang ◽  
Anguo Zhang ◽  
Xiaolong Yang ◽  
...  

Seawater acidification and warming have been found to affect the early life of many marine organisms, but their effects on the microbial community in the environment related to the early development stage of aquaculture species have been rarely investigated. To understand how seawater acidification and warming impact the microbial community in aquaculture systems, we designed four microcosms to monitor and characterize the microbial composition on the corrugated plates in the Apostichopus japonicus culture tanks during its post-settlement stage. High-throughput 16S rRNA sequencing revealed that the bacterial community composition varied significantly in different periods of incubation. The bacterial diversity and community composition were obviously changed by seawater acidification and warming in the early period and then tended to revert to the level of the control group. Acidification significantly increased the relative abundance of dominant families Rhodobacteraceae and Flavobacteriaceae in the early period, suggesting that microbiota could increase the abundance of predominant taxa to adapt to increased CO2 concentration and reconstruct a stable community structure. No interaction effect of both factors was observed in the combined group. Results reveal that the microbial communities on the corrugated plates in A. japonicus culture tank were affected in the early period of incubation, and could then acclimatize to the increased CO2 and temperature. This study provides new insights into the variation and adaptation responses of the microbiota in aquaculture systems to seawater acidification and warming.


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