一株新疆灵芝的鉴定及生长和产糖性能初探

以新疆阿勒泰采集的灵芝子实体XJ-001为试材,采用组织分离纯化获得该菌纯培养,以菌丝体基因组DNA为模板进行ITS片段扩增,测序并进行系统发育分析;以5种不同培养基培养菌株,通过比较生长速度,选出适宜母种培养基;摇瓶发酵研究不同碳氮源对菌株菌丝体生物量、胞内及胞外多糖含量的影响。结果表明:根据形态特征结合rDNA-ITS分析,初步将XJ-001鉴定为Ganoderma lucidum,并获得GenBank登录号为KT997431;菌株在玉米粉、豆饼粉琼脂培养基长势最优,生长速度为18.7mm·d~(-1);以葡萄糖、酵母浸粉为最适碳、氮源,在转速150r·min~(-1),30℃培养5d,菌株XJ-001菌丝体生物量、胞内/外多糖含量分别为8.15、1.18、0.05mg·mL~(-1)。该菌株具有生长迅速和产糖较高的潜在性能,可为开发新疆野生灵芝资源提供参考。     

Selection for root colonising bacteria stimulating wheat growth in saline soils

High salinity of soils in arid and semi-arid regions results in desertification and decreased crop yield. One possibility to circumvent this problem is to use root colonising salt tolerant bacterial inoculants which can alleviate salt stress in plants. In the present work, the best five enhanced wheat root tip coloniser bacteria were selected from the rhizosphere of wheat grown in saline soil and were identified by the 16S rRNA gene sequence as Pseudomonas putida, Pseudomonas extremorientalis, Pseudomonas chlororaphis and Pseudomonas aurantiaca. The isolates tolerated salt of 5% NaCl and produced indole acetic acid under saline conditions. Four isolates proved to be very efficient in promoting a significant increase in the shoot, root and dry matter of wheat and were able to survive in saline soil. Four of the isolated strains appeared to be better competitive colonisers than reference strains and probably outcompeted with indigenous microorganisms of the rhizosphere. These results are promising for the application of selected environmentally save microbes in saline agricultural soils.     

Bacteria able to control foot and root rot and to promote growth of cucumber in salinated soils

The aim of the present work was to test known bacterial plant growth-promoting strains for their ability to promote cucumber plant growth in salinated soil and to improve cucumber fruit yield by protecting these plants against soil-borne pathogens. Fifty-two plant-beneficial bacterial strains were evaluated for their ability to protect plants against cucumber foot and root rot after bacterization of the seeds and infestation of salinated soil with the isolated Fusarium solani pathogen. Based on the results of initial screenings, five efficient strains were selected, namely Serratia plymuthica RR-2-5-10, Stenotrophomonas rhizophila e-p10, Pseudomonas fluorescens SPB2145, Pseudomonas extremorientalis TSAU20, and P. fluorescens PCL1751. All five strains are salt tolerant since they grow well in a medium to which 3% NaCl was added. Infestation of the soil with F. solani resulted in an increase of the percentage of diseased plants from 17 to 54. Priming of seedlings with the five selected bacterial strains reduced this proportion to as low as 10%. In addition, in the absence of an added pathogen, all five strains showed a significant stimulatory effect on cucumber plant growth, increasing the dry weight of whole cucumber plants up to 62% in comparison to the non-bacterized control. The strains also increased cucumber fruit yield in greenhouse varying from 9% to 32%. We conclude that seed priming with the selected microbes is a very promising approach for improving horticulture in salinated soils. Moreover, allochthonous strains isolated from non-salinated soil, from a moderate or even cold climate, and from other plants than cucumber, functioned as well as autochthonous strains as cucumber-beneficial bacteria in salinated Uzbek soils. These results show that these plant-beneficial strains are robust and they strongly suggest they can also be used successfully in case the climate gets warmer and the soils will become more salinated. Finally, the mechanisms by which they may exert their plant-beneficial action are discussed.