绿汁发酵液中的微生物多样性及其对菌糠发酵品质的影响

本试验旨在通过高通量测序技术,测定分析5种不同原料制备的绿汁发酵液的微生物分布情况,通过Alpha多样性、主成分分析等解明其微生物群落结构。同时,为探究其微生物与发酵品质的关联性,本试验调制了对照组（无添加）和添加2%绿汁发酵液的5个菌糠青贮处理组,每个处理5个重复。结果表明：5种材料制作的绿汁发酵液样本通过Illumina Miseq测序平台共获得548 266条高质量有效序列,经分类学鉴定分属23门,129属,其中丰度大于1%的有9属。聚类分析结果表明甘蔗梢、玉米秸秆和葛藤绿汁发酵液归为一类,红象草和菌糠绿汁发酵液各自单独一类。5种绿汁发酵液处理组的菌糠青贮料乳酸含量显著（P<0.05）升高,丁酸含量显著（P<0.05）降低,能够提高青贮料的发酵品质。其中,红象草绿汁发酵液处理菌糠的发酵效果最佳,原因是象草绿汁发酵液中与青贮发酵密切相关菌属的分布比例最高。     

海带及其共附微生物的生物活性研究进展

综述了海带的活性物质及其共附生微生物的生物活性研究进展。     

Control of rice sheath blight by phyllosphere epiphytic microbial antagonists

Epiphytic microorganisms on the phyllosphere of traditional and high-yielding rice varieties were isolated from different agroecological zones of Sri Lanka and screened for theirin vitro andin vivo antagonism againstRhizoctonia solani Kühn AG-1 1A, the sheath blight pathogen of rice. Among a total of 196 bacterial and 91 fungal isolates, 12 bacterial and two fungal isolates which showed more than 50% growth inhibition ofR. solani were tested for theirin vivo antagonism. Among the 14 antagonists tested, six bacterial and one fungal isolate substantially reduced the incidence of sheath blight (by more than 82%) and severity (by more than 92%) of the rice varieties BG94-1 and IR8 grown in a pot experiment under open field conditions. Using five antagonists that showed the bestin vitro antagonism, a pot experiment was conducted to determine whether the presence of indigenous microflora on the rice sheath had any effect on the effectiveness of antagonism. Three isolates (B4, GbB5 and HMWB4) controlled sheath blight incidence and severity equally well in the presence and absence of indigenous microflora. Two isolates (BG352B1 and BG300B1) were more effective when they were introduced into the rice sheath without indigenous microflora. Among the effective antagonists determined by the pot experiment, isolates B4, B16, BG94-1B5, GbB5, HMWB4 and BG379-F2 were tested under field conditions for two consecutive growing seasons. Under field conditions, severity of rice sheath blight was significantly reduced by the application of all the tested antagonists as a spray on rice sheath at a concentration of 10⁸ cfu ml⁻¹, starting 3 days after the development of symptoms and continuing for three applications at 10-day intervals. Antagonistic performances were consistent in the two seasons under field conditions andB. megatarium A (isolate B16) andAspergillus niger (isolate BG379-F2) performed as the most effective antagonists in both seasons. When disease severity was quantified as percentage sheath area covered by the disease lesions, the respective reductions in disease severity were greater than 50% and 61% byB. megaterium A (isolate B16) andAspergillus niger (isolate BG379-F2), respectively, in both seasons. http://www.phytoparasitica.org posting Jan. 10, 2008.     

Impacts of silvicultural treatments on arboreal lichen biomass in balsam fir stands on Québec's Gaspé Peninsula: Implications for a relict caribou herd

We investigated immediate, medium and long-term effects of logging on arboreal lichen biomass in old-growth balsam fir forests (Abiesbalsamea (L.) Mill.) in the highlands of Québec's Gaspé Peninsula using three complementary approaches. Firstly, we estimated the immediate loss of lichen biomass following logging and the annual lichen litterfall from remnant trees over 2 post-logging years. Treatments included selection cutting at three intensities (25, 30, 35%), diameter-limit cutting and cutting with protection of regeneration and soils (CPRS). Among studied treatments, we found that CPRS and diameter-limit cutting removed almost all the standing lichen biomass, while selection and partial cut allowed an immediate retention of ∼40–60% of the initial lichen biomass. Our results also suggested that the impact of logging on lichen litterfall rates were higher in silvicultural treatments (3–8.5%) compared to controls (1–2%); litterfall rates did not differ after 1 or 2 years post-treatment. Secondly, we evaluated medium-term effects by comparing pre-harvest fruticose lichen biomass data with data collected at the same site 4 years after experimental thinning operations. Mean fruticose lichen biomass did not change 4 years post-harvest. However, Bryoria spp. biomass did increase relative to Alectoriasarmentosa while Usnea spp. remained unchanged. Finally, the long-term logging effects were assessed by evaluating fruticose lichen biomass along a forest chronosequence in stands aged 30, 50, 70 and 90 years. Lichen biomass increased as a function of time for all genera, especially Alectoria. Logging activities result in direct losses of lichen biomass, but careful selection cutting that retains large lichen bearing trees and maintains post-harvest conditions not detrimental to lichen growth, particularly for Bryoria spp., can ensure a substantial biomass of lichens post-harvest. Such measures may ultimately contribute to maintaining woodland caribou herds that rely on arboreal lichens.     

Unravelling the phylogenetic relationships of lichenised fungi in Dothideomyceta

We present a revised phylogeny of lichenised Dothideomyceta (Arthoniomycetes and Dothideomycetes) based on a combined data set of nuclear large subunit (nuLSU) and mitochondrial small subunit (mtSSU) rDNA data. Dothideomyceta is supported as monophyletic with monophyletic classes Arthoniomycetes and Dothideomycetes; the latter, however, lacking support in this study. The phylogeny of lichenised Arthoniomycetes supports the current division into three families: Chrysothrichaceae (Chrysothrix), Arthoniaceae (Arthonia s. l., Cryptothecia, Herpothallon), and Roccellaceae (Chiodecton, Combea, Dendrographa, Dichosporidium, Enterographa, Erythrodecton, Lecanactis, Opegrapha, Roccella, Roccellographa, Schismatomma, Simonyella). The widespread and common Arthonia caesia is strongly supported as a (non-pigmented) member of Chrysothrix. Monoblastiaceae, Strigulaceae, and Trypetheliaceae are recovered as unrelated, monophyletic clades within Dothideomycetes. Also, the genera Arthopyrenia (Arthopyreniaceae) and Cystocoleus and Racodium (Capnodiales) are confirmed as Dothideomycetes but unrelated to each other. Mycomicrothelia is shown to be unrelated to Arthopyrenia s.str., but is supported as a monophyletic clade sister to Trypetheliaceae, which is supported by hamathecium characters. The generic concept in several groups is in need of revision, as indicated by non-monophyly of genera, such as Arthonia, Astrothelium, Cryptothecia, Cryptothelium, Enterographa, Opegrapha, and Trypethelium in our analyses.     

Effects of temperature,free moisture duration and inoculum concentration on infection of sweet cherry by<Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv.<Emphasis Type="Italic">syringae</Emphasis>

The effects of temperature, free moisture duration and inoculum concentration on infection caused byPseudomonas syringae pv.syringae (Pss), on sweet cherry (Prunus avium) were investigated. Epiphytic populations ofPss are an important source of inoculum for bacterial canker and it has been demonstrated that a cyclic pattern exists during the year, from undetectable during the warm and dry periods to large populations following cool and wet periods. The effects of temperature and inoculum concentration on the infection caused byPss on immature fruits and 1-yr-old twigs were significant (P<0.001). Fruit and twig infection increased linearly in proportion to the logarithm ofPss when bacterial concentrations were higher than 10³ cfu ml⁻¹ and temperatures were between 5 and 20°C. Regardless of the inoculum concentration and the free moisture duration, fruit and twig infection was either absent or low at 5°C but it increased linearly as temperature increased from 5 to 20°C. Growth ratein vitro was very slow (0.03–0.04 cfu h⁻¹) at 5°C and fast (0.21–0.23 cfu h⁻¹) at 20°C. Therefore, it is possible that multiplication of the epiphytic populations may be significantly reduced in the field with air temperatures below 5°C. A significant (P<0.001) effect of free moisture was obtained only when a low inoculum concentration (10³ cfu ml⁻¹) was used, and a significant linear response between free moisture and disease incidence was obtained only at 10°C. An apparent threshold population ofPss higher than 10³ cfu ml⁻¹ was needed to infect immature fruits and 1-yr-old twigs of sweet cherry. http://www.phytoparasitica.org posting July 10, 2002.     

Effect of crushing unhulled rice and the addition of fermented juice of epiphytic lactic acid bacteria on the fermentation quality of whole crop rice silage, and its digestibility and rumen fermentation status in sheep

This experiment was carried out to examine the effect of crushing unhulled rice and the addition of fermented juice of epiphytic lactic acid bacteria (FJLB) on the fermentation quality of whole crop rice silage, and its digestibility and rumen fermentation in sheep. After whole rice plants (Oryza sativa L. cv. Haenuki) were harvested between the yellow and full‐ripened period of maturity, and cut at a length of 2 cm, four silage treatments were set: (i) non‐treatment; (ii) crushing treatment of unhulled rice division (crushing); (iii) addition of 1% FJLB; and (iv) crushing + addition of 1% FJLB. Lactic acid content increased with the addition of FJLB, and was highest in the crushing + FJLB treatment. Digestibilities of crude fiber, acid detergent fiber and neutral detergent fiber were significantly higher during the crushing + FJLB treatment. There were no differences among treatments in the volatile fatty acid concentrations before and after feeding. At 4 h after feeding, however, the ratio of acetic acid : propionic acid was significantly lower with the addition of FJLB. It was proven that the fermented quality of silage was improved when FJLB was added to rice plants and then ensilaged, and the digestibility of the fibrous component was raised when unhulled rice division was crushed and FJLB was supplemented.     

柑桔树附生苔藓地衣的危害及治理

树附生苔藓对附生树的危害研究甚少,对果树的危害认知不足。通过调查陕南柑桔主产区城固、汉台等地的柑桔园,盛果期丰产园柑桔树附生苔藓感染指数近80%,年柑桔树致死率最高达2.99%,并随树龄增加而加重之势明显。从植物病理学角度出发,研究柑桔树附生苔藓地衣危害过程、症状表现、分级方法、发生规律及原因等方面,提出防治措施,为柑桔生产中苔藓地衣的防治提供参考。     

A sterilization technique with applications to silage research and inoculant evaluation

Different techniques were tested to sterilize grass samples with respect to epiphytic microflora (lactic acid bacteria, enterobacteria, yeasts and moulds) to enable study of specific microfloras. Methods tested on freshly harvested grass samples included sterilization efficacies of ethanol, combined effects of ethanol and sodium hypochlorite, neutral detergents and cold shock. The antimicrobial properties of moist and dry heat were also tested, although on freeze‐dried samples to minimize the extent of Maillard reactions. Sterilization efficacy was evaluated by culture‐dependent microbial analysis. Heat was found to be the best antimicrobial agent. Moist heat (autoclaving) produced chemical changes including a fivefold increase in concentration of acid detergent insoluble nitrogen and reduced pH value. The results suggest that dry heating of dried samples before reconstituting to original dry‐matter content could be a promising sterilization technique. Fine‐tuning the technique and testing the ensilability of reconstituted samples are the next steps to be undertaken.