臘狀芽孢桿菌C1L內孢子製劑之發展與應用

Abstract

已知臘狀芽孢桿菌C1L菌株可以促進玉米植株生長，並有助於玉米抗南方葉枯病及臺灣百合、葵百合、阿卡波克百合抗灰黴病。為了發展可以穩定保存之製劑，本研究探討C1L內孢子的生產條件、製劑型式及應用功效。首先選擇C1L菌株產孢最適條件並擴大培養體積至3公升，以添加0.01%消泡劑之NB液態培養基進行發酵，培養2天的產孢率可達81%。將自發酵液所得的菌體冷凍乾燥並存放於室溫，計量之內孢子數由初始濃度1011 CFU/g至第十三個月仍維持在1010 CFU/g。由溫室試驗確認C1L內孢子促進玉米植株抗病之作用，以內孢子懸浮液處理1天後，對葉枯病即有明顯的防治效果，所誘導之抗病性可持續6天；並於菸草與阿拉伯芥上確認C1L內孢子與細菌懸浮液對植物之生長均有促進作用。進一步，選取多孔性載體試製C1L內孢子製劑，以吸附內孢子之真珠石有較佳的抑病作用；有機質肥料則可輔助吸附內孢子之真珠石的抑病作用。兩種測試之有機質肥料(I、II)無法增加植物抗病性，但可加強吸附內孢子之真珠石對植物抗病性的促進作用。玉米與葵百合之田間試驗結果指出，有機質肥料(I、II)可促進植株生長，但無法增加植株之抗病性；內孢子懸浮液不但能促進植株生長，並有很好的病害防治效果；當吸附內孢子之真珠石混拌有機質肥料I施用時，對植株生長、抗病的促進效果與澆灌內孢子懸浮液相當。本研究所建立之載體與輸送方式將可作為C1L菌株製劑化與應用之參考依據。

Bacillus cereus C1L could promote maize growth, induce disease resistance to southern corn leaf blight and Botrytis leaf blight in Lilium formosanum, Lilium ‘Star gazer’ and Lilium ‘Acapulco’. Previous studies demonstrated the great efficacy of strain C1L in promoting plant growth and inducing systemic resistance of maize against southern leaf blight in field conditions. This research aimed to produce endospores of high density, develop endospore-based bioagent and test on activities of plant growth promotion and induced systemic resistance. The endospores of strain C1L produced in 3-L culture with 0.01% anti-foaming agent reached about 81% sporulation rate after 2-day incubation. The freeze-dried powder of 1011 endospores per gram, maintained 1010 endospores per gram over 13-month storage period. In greenhouse assays, application of endospore suspensions could reduce disease severity of southern corn leaf blight when fungal pathogen was challenge-inoculated 1-6 days after bacterial treatment. Seed bacterization of tobacco and Arabidopsis with 1´108 CFU/ml of C1L endospores as well as vegetative cells significantly conducted better plant height, dry weight, and root length as compared to the untreated control. Porous media were tested as carriers of C1L endospores. Among them, perlite was best for delivery of C1L endospores as shown by the biocontrol assay in maize. Two kinds of organic fertilizers (I and II) were unable to enhance disease resistance of maize. However, combined application with organic fertilizer I could increase the effect of endospore-carried perlite on the induction of systemic resistance against southern corn leaf blight. The field assays of maize and Lilium ‘Star Gazer’ indicated that organic fertilizers could promote plant growth, but unable to reduce disease severity. However, application of endospore-carried perlite not only conferred better plant protection, but also promoted plant growth as applied with organic fertilizer I. The delivery system of C1L endospores developed in this study would become a valuable basis for the formulation and application of B. cereus C1L.