Sponsor(s): Institute of Microbiology, CAS; Chinese Society for Microbiology
12 issues per year
Current Issue: Issue 08, 2020
Microbiology China is supervised by Chinese Academy of Sciences, sponsored by Chinese Society for Microbiology and Institute of Microbiology, CAS. Impact factor is 1.336.
Editor-in-Chief: Hao Rongqiao
Diversity and function of culturable rhizospheric bacteria of flue-cured tobacco K326 intercropped with five spice plants
Microbiology China,2020,Vol 47,No. 08
[Background] Flue-cured tobacco is an important economic crop in China. Intercropping affects the diversity of rhizospheric microorganisms and alleviates the production of flue-cured tobacco. Rhizospheric microorganisms can adapt to changes in the rhizosphere microenvironment, which promotes the growth of flue-cured tobacco. [Objective] We examined the diversity of the bacterial population in flue-cured tobacco’s rhizosphere soil under the intercropping models between tobacco K326 and five spice plants at different growth periods. In addition, we compared the variances in intercropping modes in various growing periods from the perspective of biological diversity and subsequently screened the adaptability and functional characteristic of typical rhizosphere bacterium. [Methods] Soil samples from various growing periods with different intercropping modes were collected. We designed the culturing method to isolate and sequence the 16S rRNA gene, and calculated the diversity index. Representative strains were selected to detect nicotine and Cr 6+ tolerance as well as growth-promoting properties. [Results] A total of 707 bacterial strains distributed in 70 genera were isolated. The change of the Shannon index of bacteria in flue-cured tobacco’s rhizosphere soil at the stem elongation period was W (4.079 191 7) > 2GAY (3.840 352 1) > 2GDY (3.514 562 8) > 2GCKY (3.497 703 4) > 2GBY (3.447 478 9) > 2GCY (3.253 409 2) > 2GEY (3.241 103 4). The change of Shannon index of bacteria in flue-cured tobaccos’ rhizosphere soil at the leaf ripening period was 3GAY (3.688 981 7) > 3GCKY (3.442 125 1) > 3GBY (3.353 155 8) > 3GDY (3.349 171 9) > 3GEY (3.306 294 5) > 3GCY (3.305 582 2). The change of Shannon index of bacteria in flue-cured tobacco’s rhizosphere soil at the harvesting period was 5GEY (2.857 102 8) > 5GBY (2.458 311 3) > 5GAY (2.271 868 5) > 5GCKY (2.210 253 6) > 5GCY (2.079 441 5) > 5GDY (0.693 147 2). The genera Arthrobacter, Bacillus, Brevibacillus, Brevendimononas, Microbacterium, Nocardioides, Pseudomonas, Rhodococcus, Streptomyces and Terrabacter were detected at all the three growth periods. Majority of the representative strains exhibited positive activities for nicotine tolerance, Cr 6+ tolerance, nitrogen fixation, siderophore production, phosphorus solubilization and starch hydrolysis. [Conclusion] Rhizosphere soil contained abundant bacterial resources under the intercropping mode between five spice plants and the flue-cured tobacco K326. Among the dominant bacterial groups in flue-cured tobacco’s rhizosphere soil, the genera Bacillus, Pseudomonas and Streptomyces had potential applicability in nicotine tolerance, Cr 6+ tolerance and growth-promoting effects. The intercropping can change the diversity of bacteria in rhizosphere soil of flue-cured tobacco. In the tobacco leaf ripening period, the intercropping of five spice plants and flue-cured tobacco significantly increased the diversity of cultivable bacteria in the rhizosphere soil. The intercropping modes of Monarda didyma, Cymbopogon citratus and Pelargonium graveolens owned advantages in relieving continuous cropping of flue-cured tobacco.
Exploring mechanisms for Bacillus amyloliquefaciens-mediated production performance improvement of laying hens based on cecal microflora and ileum mucosal gene expression
Microbiology China,2020,Vol 47,No. 08
[Background] Bacillus amyloliquefaciens BLCC1-0238 supplementation has been reported to effectively improve production performance and egg quality of laying hens in our previous study, the underlying mechanism, however, remains poorly understood. [Objective] The current study was conducted to examine the potential mechanism of B. amyloliquefaciens BLCC1-0238 to increase the production performance of laying hens by evaluating cecal microflora and gene expression in ileum mucosa. [Methods] High-throughput sequencing technology was used to compare the differences of cecal microflora composition and gene transcription level of ileum mucosa between the basal diet group (group C) and B. amyloliquefaciens BLCC1-0238 supplementation group (0.06%, 2.0 × 10 10 CFU/g, group T). [Results] B. amyloliquefaciens BLCC1-0238 supplementation can produce higher indexes of Chao1 and Shannon, which demonstrated increased diversity of cecal microflora. At the phylum level, the Firmicutes/Bacteroidetes ratio significantly increased, while relative abundance of Fusobacteria and Proteobacteria reduced. At the genus level, the relative abundance of Phascolarctobacterium, Lactobacillus, Ruminococcaceae UCG-014, Anaerotruncus, Ruminiclostridium 9, and Christensenellaceae_R-7_ group all elevated. These results indicated that B. amyloliquefaciens BLCC1-0238 supplementation altered the cecal microflora composition from different levels. With respect to gene expression change in ileum mucosa, 356 differentially expressed genes were identified, among which 199 genes were up-regulated and 157 genes were down-regulated. Bioinformatics analysis found that these up-regulated genes were involved in the signaling pathways associated with nutrition metabolism, such as glycine, serine and threonine metabolism, starch and sucrose metabolism, and galactose metabolism, which may accelerate nutrition absorption of laying hens. [Conclusion] B. amyloliquefaciens BLCC1-0238 supplementation can effectively improve laying hen production performance via increasing the diversity of cecal microflora and promoting nutrition absorption of laying hens, providing solid evidence for its practical application in the future.
Isolation, identification and characterization of an antagonistic bacterium against Bipolaris papendorfii
Microbiology China,2020,Vol 47,No. 08
[Background]Bipolaris papendorfii is the main fungal pathogen of Curvularia leaf spot, and harmful to agricultural production. At present, the use of bacteria to control B. papendorfii becomes a research focus in this field. [Objective] To screen the strains with high antagonistic activity against B. papendorfii, and identify the antagonistic mechanism. [Methods] Twenty-two bacterial strains were isolated from the soil under the surface of maize field by the method of plate confrontation. One strain L-14 with high antagonistic activity to B. papendorfii was obtained by repeated screening. [Results] Strain L-14 with the highest antagonism was obtained by using the plate diffusion method. After morphological observation, 16S rRNA gene sequence analysis, physiological and biochemical characteristics detection, the strain was finally identified as Bacillus subtilis. Moreover, the strain is a wide-spectrum antagonistic biocontrol strain with inhibitory effects on Fusarium proliferatum, Fusarium graminearum, Exserohilum turcicum, Bipolaris papendorfii and Botrytis cinerea. Then, we studied the antibacterial mechanism of strain L-14 and obtained that the fermentation crude protein extracts had no effect on the morphology of the aerial hyphae of B. papendorfii but can cause substrate mycelial aberration, and had an inhibitory effect on spore germination. [Conclusion] The antagonistic bacterium B. subtilis obtained in this study has a broad spectrum and high antagonistic activity in the control of plant diseases, and can effectively control Curvularia leaf spot.