Morpho-cultural, Pathogenicity and Molecular Characterization of Phyllosticta capitalensis Inciting Cavendish Banana Freckle Disease in Hainan

[Objectives]The study was to identify the casual agent of freckle disease on Cavendish banana in Hainan Province,China.[Methods]Fungal isolates were isolated from affected leaf tissues and identified by the morphological features,molecular identification and pathogenicity test.[Results]The fungus isolated from affected leaf tissues was identified as Phyllosticta capitalensis based on the morphological properties of the colony and spore,coupled with sequence analyses of the internal transcribed spacer(ITS)region and the large subunit(LSU)rDNA gene.Koch s postulates were fulfilled by successfully re-isolating the pathogen from the artificial inoculated leaves.[Conclusions]P.capitalensis is a new pathogen responsible for Cavendish banana freckle disease in Hainan.

Biological Characteristics of the Pathogen Phyllosticta capitalensis Causing Banana Freckle Disease in Hainan Province

[Objectives]This study was conducted to clarify the biological characteristics of the pathogen Phyllosticta capitalensis,the causal agent of freckle disease on Cavendish banana in Hainan Province,China.[Methods]The impact of various nutritional and environmental factors,including media,carbon sources,nitrogen sources,temperature,pH and light on the growth and sporulation of P.capitalensis was assessed using two distinct methods:mycelium growth rate and blood counting chamber.[Results]The mycelial growth and sporulation of P.capitalensis on different media exhibited notable differences.The use of banana leaf extract dextrose agar(BLEAD)and carrot agar(CA)was observed to facilitate rapid mycelial growth.The potato dextrose agar(PDA)and potato sucrose agar(PSA)were conducive to the production of conidia.The utilization of distinct carbon and nitrogen sources exerted a pronounced influence on the growth of P.capitalensis.Maltose,dextrose,fructose,and casein acid hydrolysate were the preferred substrates for mycelial growth.The tested carbon and nitrogen sources did not significantly stimulate conidial production,whereas dextrose and NaNO 3 were found to favor sporulation.The optimal temperature for mycelial growth and conidial production was determined to be 28 and 32℃,respectively.No mycelial growth was observed at 5℃.Active mycelial growth was observed at pH 6-10,with pH 6-7 being particularly conducive to sporulation.Complete darkness was conducive to mycelial growth and sporulation.[Conclusions]It is recommended that BLEDA and PDA should be incubated at 28℃for 14 d in the dark for the purpose of mycelial growth and sporulation of P.capitalensis,respectively.

典型有机固废厌氧消化微生物研究现状与发展方向

经过人工富集和驯化的兼性和严格厌氧微生物是厌氧消化工艺的核心。不同厌氧消化体系中存在的问题大多可以通过改变微生物群落的代谢活性来得到有效改善。得益于微生物组学检测技术的快速发展,对厌氧消化系统中微生物多样性的认识获得了极大的拓展,同时在微生物类群间、微生物与环境的互作关系研究方面也取得了一系列新的进展。然而,有机固废厌氧消化系统中,各种微生物以及微生物和物质的相互作用构成了更为复杂的代谢网络,所以目前对这些互作关系的解析尚不完善。本文重点关注了厌氧消化过程中的典型菌群互作关系,阐述了典型有机固废厌氧消化系统中存在的问题及微生物在其中发挥的作用,最后,立足于现有组学技术推动的微生物组研究进展,对未来有机固废厌氧消化系统微生物组的研究提出展望。

全球变化下海岸带微生物生态研究进展

海岸带地区是元素循环最活跃的自然区域之一,微生物作为地球元素循环的主要驱动者,对该区域生态系统中物质转化与能量流动起着至关重要的作用。本文从典型海岸带生态系统:海岸带湿地、海草床与海藻森林、近岸水体出发,围绕微生物参与的碳、氮循环过程以及其中的温室气体排放情况,综述了在全球气候变化与人为活动干扰的作用下,海岸带地区的微生物群落对外界环境变化的响应机制以及生态功能维持机制,最后对海岸带系统中微生物生态研究进行了初步的展望。

Biodegradation of indole by a newly isolated Cupriavidus sp. SHE

Indole, a typical nitrogen heterocyclic aromatic pollutant, is extensively spread in industrial wastewater. Microbial degradation has been proven to be a feasible approach to remove indole, whereas the microbial resources are fairly limited. A bacterial strain designated as SHE was isolated and found to be an efficient indole degrader. It was identified as Cupriavidus sp. according to 16 SrRNA gene analysis. Strain SHE could utilize indole as the sole carbon source and almost completely degrade 100 mg/L of indole within 24 hr. It still harbored relatively high indole degradation capacity within p H 4–9 and temperature 25°C–35°C. Experiments also showed that some heavy metals such as Mn2＋, Pb2＋and Co2＋did not pose severe inhibition on indole degradation. Based on high performance liquid chromatography–mass spectrum analysis, isatin was identified as a minor intermediate during the process of indole biodegradation. A major yellow product with m/z 265.0605（C15H8N2O3） was generated and accumulated, suggesting a novel indole conversion pathway existed. Genome analysis of strain SHE indicated that there existed a rich set of oxidoreductases, which might be the key reason for the efficient degradation of indole. The robust degradation ability of strain SHE makes it a promising candidate for the treatment of indole containing wastewater.

the National Natural Science Foundation of China(41877029,41961130383);Royal SocietyNewton Advanced Fellowship(NAF\R1\191017);Wuhan Science and Technology Bureau(2019020701011469).

Due to the tremendous diversity of microbial organisms in topsoil,the estimation of saturated richness in a belowground ecosystem is still challenging.Here,we intensively surveyed the 16S rRNA gene in four 1 m2 sampling quadrats in a typical grassland,with 141 biological or technical replicates generating over 11 million sequences per quadrat.Through these massive data sets and using both non-asymptotic extrapolation and non-parametric asymptotic approaches,results revealed that roughly 15919±193,27193±1076 and 56985±2347 prokaryotic species inhabited in 1 m2 topsoil,classifying by DADA2,UPARSE(97%cutoff)and Deblur,respectively,and suggested a huge difference among these clustering tools.Nearly 500000 sequences were required to catch 50%species in 1 m2,while any estimator based on 500000 sequences would still lose about a third of total richness.Insufficient sequencing depth will greatly underestimate both observed and estimated richness.At least~911000,~3461000,and~1878000 sequences were needed for DADA2,UPARSE,and Deblur,respectively,to catch 80%species in 1 m2 topsoil,and the numbers of sequences would be nearly twice to three times on this basis to cover 90%richness.In contrast,α-diversity indexes characterized by higher order of Hill numbers,including Shannon entropy and inverse Simpson index,reached saturation with fewer than 100000 sequences,suggesting sequencing depth could be varied greatly when focusing on exploring differentα-diversity characteristics of a microbial community.Our findings were fundamental for microbial studies that provided benchmarks for the extending surveys in large scales of terrestrial ecosystems.

Soil microbiome mediated nutrients decline during forest degradation process

Degradation succession in forests is an important and serious land use/cover change problem in ecology,and during these processes soil microbial communities mediate the recycling of most important nutrients.To reveal the effect of degradation succession processes on soil microbial community diversity,structure,and species interrelationships,we collected abundant samples(21 per vegetation type)in broad-leaved forest,coniferous forest,and meadow to observe the microbial community dynamics.The results showed that diversity and structure of soil prokaryotic and fungal communities responded differently to different forest degradation processes,diversity of soil microbial communities increased during degradation processes.Soil microbial communities abundance changes may indicate that prokaryotic communities showed a living strategies change as an ecological adaption to harsh conditions during forest degradation process.While for fungal communities,their abundance changes may indicate that environmental selection pressure and plant selectivity during forest degradation process.Changes in soil prokaryotic communities and fungal communities were both correlated with soil carbon and nitrogen loss.The soil microbial interaction network analysis indicated more complex species interrelationships formed due to the loss of soil nutrients during degradation succession processes,suggesting soil microbial communities might form more complex and stable networks to resist the external disturbance of soil nutrient loss.All results suggested soil microorganisms,including bacteria,archaea and fungi,all involved in the soil nutrient decline during the forest degradation process.