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Journal of Zhejiang University SCIENCE B

ISSN 1673-1581(Print), 1862-1783(Online), Monthly

Statistical culture-based strategies to enhance chlamydospore production by Trichoderma harzianum SH2303 in liquid fermentation

Abstract: Trichoderma-based formulations are applied as commercial biocontrol agents for soil-borne plant pathogens. Chlamydospores are active propagules in Trichoderma spp., but their production is currently limited due to a lack of optimal liquid fermentation technology. In this study, we explored response surface methodologies for optimizing fermentation technology in Trichoderma SH2303. Our initial studies, using the Plackett-Burman design, identified cornmeal, glycerol, and initial pH levels as the most significant factors (P<0.05) for enhancing the production of chlamydospores. Subsequently, we applied the Box-Behnken design to study the interactions between, and optimal levels of, a number of factors in chlamydospore production. These statistically predicted results indicated that the highest number of chlamydospores (3.6×108 spores/ml) would be obtained under the following condition: corn flour 62.86 g/L, glycerol 7.54 ml/L, pH 4.17, and 6-d incubation in liquid fermentation. We validated these predicted values via three repeated experiments using the optimal culture and achieved maximum chlamydospores of 4.5×108 spores/ml, which approximately a 8-fold increase in the number of chlamydospores produced by T. harzianum SH2303 compared with that before optimization. These optimized values could help make chlamydospore production cost-efficient in the future development of novel biocontrol agents.

Key words: Trichoderma harzianum SH2303, Chlamydospore, Plackett-Burman screening, Box-Behnken design, Fermentation optimization

Chinese Summary  <26> 哈茨木霉菌SH2303高产厚垣孢子液体发酵优化

目的:鉴于厚垣孢子为主要活性成分的木霉菌剂具有 抗逆性强、存活期长、易贮藏等特点,更容易满足实际生产需求,本文利用系统的液体发酵策略,优化木霉菌高产厚垣孢子液体发酵条件,同时降低发酵成本,指导未来木霉菌厚垣孢子生防菌剂研发。
创新点:采用从开放到闭合的递进式液体发酵筛选优化模式,通过Plackett-Burman设计和Box-Behnken优化设计确定影响木霉菌产厚垣孢子的关键因子及最佳发酵条件,确定玉米粉作为基础培养基,添加甘油和调节pH相结合的液体发酵策略,在降低发酵成本的同时提高厚垣孢子产量。
方法:以玉米粉为基础培养基,通过Plackett-Burman筛选实验,从8个候选的发酵因子中初步确定玉米粉、甘油和发酵液起始pH值三个显著因子。进而利用响应面中的Box-Behnken设计(表5)三个因素为自变量,厚垣孢子产量为响应值,通过Design Expert 7.0软件对实验数据进行多项式回归分析,建立多元二次回归方程。通过方差分析,最终确定木霉菌SH2303高产厚垣孢子液体发酵工艺的最佳参数。
结论:确定了影响厚垣孢子形成的三个关键的发酵因子:玉米粉、甘油和起始pH值。获得厚垣孢子形成最佳的液体发酵条件:玉米粉62.86 g/L,甘油 7.54 ml/L,起始pH 4.17,发酵6天。实际最大厚垣孢子产量4.5×108 孢子/ml,与模型预测值3.6×108 孢子/ml相当。厚垣孢子产量与优化前相比提高8倍,可用于指导低成本的木霉菌厚垣孢子新型生防菌剂开发。

关键词组:哈茨木霉菌SH2303厚垣孢子;Plackett-Burman筛选;Box-Behnken设计;液体发酵优化


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DOI:

10.1631/jzus.B1500226

CLC number:

S476

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On-line Access:

2016-08-04

Received:

2015-09-17

Revision Accepted:

2016-01-30

Crosschecked:

2016-07-13

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