砂姜黑土中兼具促生功能的纤维素降解菌的筛选及其应用

为实现砂姜黑土地区秸秆资源化利用以及作物增产,本研究从该区小麦-玉米轮作土壤中筛选具有促生功能的纤维素降解菌株。通过羧甲基纤维素酶活(CMC)与吲哚乙酸(IAA)分泌量测定,筛选出1株具有高效降解纤维素的促生菌株。经形态学和分子生物学鉴定,该菌株为普沙根瘤菌(Rhizobium pusense),命名为X2。小麦秸秆降解和玉米盆栽初步试验结果显示,X2菌株经液态发酵15 d后小麦秸秆降解率为16.1%,较对照显著提升65.4%;接种该菌株后盆栽土壤中碱解氮含量较对照显著提高了72.7%,植株根系的平均直径、表面积以及地上部干物质量显著增加了22.0%、28.6%和33.3%。为进一步提高该菌株的活性,采用单因素试验对菌株的培养条件进行优化,结果表明,X2菌株在装液量为25 mL/250 mL、氮源为酵母粉、pH为6.0时生长和产IAA能力最优,产酶的最适pH为5.0。综上,所筛菌株X2具有秸秆降解和玉米促生能力,可在砂姜黑土地区为秸秆资源化利用提供新的微生物资源。

一株多功能秸秆木质素降解菌株的筛选、鉴定及条件优化

为实现秸秆资源化利用及提高作物产量,本研究从秸秆中筛选木质素降解菌株,并探究其多种功能,发掘微生物资源的目标。通过菌株苯胺蓝筛选培养、木质素酶活力、IAA能力测定及平板对峙试验等探究菌株促腐、促生及抗病潜能;结合形态学、生理生化特征和16S rRNA序列分析对菌株种属进行鉴定;采用秸秆摇瓶及水稻促生试验测定菌株的实际促腐促生功效;设置单因素试验探究菌株发酵的最适条件。分离筛选的功能菌M15H2鉴定为植生拉乌尔菌(Raoultella planticola)。结果显示,该菌株木质素过氧化物酶活可达129.49 U·mL^(-1),锰过氧化物酶可达23.91U·mL^(-1),漆酶酶活可达8.91 U·mL^(-1)。与对照相比,施用M15H2菌液55 d后秸秆腐解率较对照处理提高32.59%;M15H2产IAA量为3.90 mg·L^(-1),水稻植株发芽率、芽长、根长较对照处理分别增长5.67%、31%和40%;菌液M15H2具有一定的抗水稻条斑病效果,抑菌圈直径与菌落直径的比值为1.20。菌株M15H2发酵的最佳p H为5.0,温度为28~32℃,碳源和氮源分别为蔗糖和酵母粉,装液量是50 mL/250 mL。所筛选的菌株M15H2是兼具促生、抗病作用的多功能秸秆促腐菌,能够加速秸秆降解,促进植株健康生长,具有广泛的开发利用前景。

生物刺激素及其在功能水溶性肥料中应用前景分析

施用生物刺激素所带来的改土抗逆促生功能对于提高土壤养分利用效率、促进作物提质增产十分有效,深受功能性肥料行业的关注。本文从分析生物刺激素概念入手,总结了市场上普遍应用的腐植酸、氨基酸、海藻提取物和促生菌的功能特性和作用机制,并归纳了含有这些物质并可作为功能水溶性肥料载体的废弃物资源种类及应用特点,探究其与活性物质复配制备功能水溶性肥料的工艺关键,以期为实现废弃物增值化利用,实现集约化生产中肥料减施、提高作物产量和品质等目标提供产品支撑。

Research Progress of Mechanism of Action of Plant Growth Promoting Rhizobacteria

The paper first introduces the definition and classification of plant growth promoting rhizobacteria （PGPR）, then reviews the research achievements on the mechanism of action of plant growth promoting rhizobacteria, including growth pro-moting mechanism and bio-control mechanism, subsequently lists the use of excel-lent plant growth promoting rhizobacteria strains in recent years, especial y Pseu-domonas and Bacil us strains, and final y discusses problems existing in this area and points out issues requiring further exploration, including PGPR screening meth-ods, preservation methods, mechanism of action, in order to commercialize PGPR as soon as possible and practical y realize its application to production.

Deep-sea organisms research oriented by deep-sea technologies development

Deep-sea environment,characterized by high pressures,extremely high/low temperatures,limited photosynthesis-generated organic matter,darkness,and high levels of corrosion,is home to flourishing special ecosystems in the world.Here,we illustrate how the deep-sea equipment offers insights into the study of life in the deep sea based on the work in the past five decades.We first describe how organisms in the deep sea are studied,even though it is highly difficult to get access to such extreme environments.We then explain the role of deep-sea technologies in advancing research on the evolution of organisms in hydrothermal vents,cold seeps,seamounts,oceanic trenches,and whale falls from the following perspectives:biological diversity,mechanisms of environmental adaptation,biological evolution,and ecosystem connectivity.Finally,to better understand the function and service of deep-sea organisms,and further conserve the special creatures under anthropologic activity and climate change,we highlight the importance of innovative deep-sea technologies to promote cutting-edge research on deep-sea organisms,and note the remaining challenges and developing directions for deep-sea equipment.

Macleaya cordata helps improve the growth-promoting effect of chlortetracycline on broiler chickens

Chlortetracycline （CTC）, one kind of common antibiotic for prevention and treatment of various diseases, also exhibits good performance in accelerating the growth of livestock. Macleaya cordata, a traditional Chinese medicine, is usually used as a natural additive in livestock because of its anti-microbial, anti-fungal, anti-inflammatory, and pesticidal activity. In this work, we studied whether M. cordata helps regulate the growth-promoting effect of CTC on broiler chickens. It is demonstrated that M. cordata improves the growth-promoting effect of CTC on growth per- formance indices of broiler chickens, such as survival rate, daily weight, and feed to weight rate. M. cordata also delays the maximum of CTC residues in plasma. It may depend on the higher values of operational taxonomic unit （OTU） and the indices of o diversity driven by simultaneous use of CTC and M. cordata.

Bacillus amyloliquefaciens Strain W19 can Promote Growth and Yield and Suppress Fusarium Wilt in Banana Under Greenhouse and Field Conditions

Plant growth-promoting rhizobacteria （PGPR） are considered to be the most promising agents for cash crop production via increasing crop yields and decreasing disease occurrence. The Bacillus amyloliquefaciens strain W19 can produce secondary metabolites （iturin and bacillomycin D） effectively against Fusarium oxysporum f. sp. cubense （FOC）. In this study, the ability of a bio-organic fertilizer （BIO） containing strain W19 to promote plant growth and suppress the Fusarium wilt of banana was evaluated in both pot and field experiments. The results showed that application of BIO significantly promoted the growth and fruit yield of banana while suppressing the banana Fusariurn wilt disease. To further determine the beneficial mechanisms of the strain, the colonization of green fluorescent protein-tagged strain W19 on banana roots was observed using confocal laser scanning microscopy and scanning electron microscopy. The effect of banana root exudates on the formation of biofilm of strain W19 indicated that the banana root exudates may enhance colonization. In addition, the strain W19 was able to produce indole-3-acetic acid （IAA）, a plant growth-promoting hormone. The results of these experiments revealed that the application of strain W19-enriched BIO improved the banana root colonization of strain W19 and growth of banana and suppressed the Fusarium wilt. The PGPR strain W19 can be a useful biocontrol agent for the production of banana under field conditions.