Lale G, Jogdand V V, Gadre R V
Chemical Engineering Division, National Chemical Laboratory, Pune, India.
J Appl Microbiol. 2006;100(1):65-72. doi: 10.1111/j.1365-2672.2005.02754.x.
To examine the production of gibberellic acid by selected morphological mutants of Gibberella fujikuroi in liquid cultures.
Mutants of G. fujikuroi having different morphological characteristics were selected after UV irradiation. The production of gibberellic acid by mutants that had different hyphal lengths was examined in shake flasks in media with different concentrations of nutrients as well as different volumes of the medium. Fed-batch fermenter study was performed to evaluate the mutant Mor-25 for growth and production of gibberellic acid. The broth was analysed by high performance liquid chromatography for fusaric acid, the common mycotoxin produced by strains of Fusarium. A variety of morphological mutants having different mycelial and soluble pigmentation as well as colony morphologies were generated from G. fujikuroi upon exposure to UV radiation. A nonpigmented mutant (Car-1) was selected as intermediate parent and later, mutants Mor-1 and Mor-25 were selected based on their distinct morphology. The colonies on regeneration agar plates were small, compact and dry. In liquid medium, mutant Mor-25 grew in a micro-pelleted form and the mycelium had short, highly branched hyphae, curly at tips with thick, swollen cells. Mutant Mor-25 grew rapidly in a low-cost medium containing defatted groundnut flour, sucrose and salts. In media with higher nutrient concentrations as well as larger volumes, it produced twofold more gibberellic acid than the parent. Fusaric acid, the common mycotoxin, was absent in the fermentation broth of mutant Mor-25. The mutants have been deposited in National Collection of Industrial Microorganisms (NCIM), National Chemical Laboratory, Pune, India under following culture collection numbers (Car-1, NCIM 1323; Mor-1, NCIM 1322; and Mor-25, NCIM 1321).
Growth of unpigmented, morphological mutants of G. fujikuroi that led to lower viscosity in fermentation broth resulted in increased production of gibberellic acid.
The use of morphological mutants that have lower viscosity in liquid cultures for gibberellic acid production is not reported earlier. Similar mutants can be useful for other types of fungal fermentations also.
研究藤仓赤霉菌的某些形态突变体在液体培养中赤霉素的产生情况。
经紫外线照射后筛选出具有不同形态特征的藤仓赤霉菌突变体。在摇瓶中，于含有不同浓度营养物质以及不同体积培养基的条件下，检测了具有不同菌丝长度的突变体产生赤霉素的情况。进行了补料分批发酵罐研究，以评估突变体Mor - 25的生长及赤霉素产生情况。通过高效液相色谱法分析发酵液中镰刀菌酸（镰刀菌菌株产生的常见霉菌毒素）。经紫外线照射后，藤仓赤霉菌产生了多种具有不同菌丝和可溶性色素沉着以及菌落形态的形态突变体。选择了一个无色素突变体（Car - 1）作为中间亲本，随后基于其独特形态选择了突变体Mor - 1和Mor - 25。再生琼脂平板上的菌落小、紧密且干燥。在液体培养基中，突变体Mor - 25以微颗粒形式生长，其菌丝短且高度分支，顶端卷曲，细胞厚且肿胀。突变体Mor - 25在含有脱脂花生粉、蔗糖和盐的低成本培养基中生长迅速。在营养浓度较高以及体积较大的培养基中，其产生的赤霉素比亲本多两倍。突变体Mor - 25的发酵液中不存在常见霉菌毒素镰刀菌酸。这些突变体已保藏于印度浦那国家化学实验室的国家工业微生物保藏中心（NCIM），保藏编号如下（Car - 1，NCIM 1323；Mor - 1，NCIM 1322；Mor - 25，NCIM 1321）。
藤仓赤霉菌无色素形态突变体的生长导致发酵液粘度降低，从而使赤霉素产量增加。
此前未见报道在液体培养中使用粘度较低的形态突变体来生产赤霉素。类似的突变体可能对其他类型的真菌发酵也有用。
