Microorganisms Contaminated in the Process of Cultivation and Their Effect on the Production of Shiitake

香菇栽培之污染微生物及其對香菇生產之影響

廖英明(Ying-Ming Liao)

《中華農業研究》 42卷2期 (1993/06) Pp. 187-199

https://doi.org/10.29951/JARC.199306.0009

摘要

香菇污染雜菌一直是香菇栽培者及菌種製造者之主要問題，而減少污染程度則是降低成本及增加收益的方法。本文旨在檢測存在於菌種、木屑及培養基或栽培場、培養室等之微生物，及這些微生物對香菇生產之影響，進而尋求適當之pH值與殺菌方式以便降低微生物之污染藉以改進香菇栽培技術。由試驗結果可知，在香菇木屑菌種中常見之雜菌以Trichoderma，Penicillium，Neurospora及Aspergillus最多，而在麥粒菌種中則以Trichoderma，Bacillus及Aspergillus為主。香菇菌絲在麥粒菌種中之生長速度比在木屑菌種中為快。在栽培場所收集之微生物數量比在接種室或培養室者為多，而堆積在戶外之木屑其微生物含量又比在木屑培養基中者為多。在運輸販賣過程中香菇子實體表面會污染許多微生物。將這些有害微生物接種於木屑包，則可發現正常生長之木屑包其微生物量較污染包為低且pH值也較低，含水量則正常包比污染包稍高，但差異不大。木屑在戶外堆積六個月後可發現火燒柯(Castanopsis hytrix)由原來的低pH值漸漸昇高為適合香菇生長的範圍，而相思樹(Acacia confuse)及闊葉樹混合木屑也有相同的結果，惟其變化不如火燒柯大。酸性木屑培養基極適合香菇菌絲之生長，較適合之pH值為4.5至6.0，Trichoderma則除了pH7.5外，所有供試之範圍均適合生長，而Neurospora則在所有測試pH值中均生長緩慢，只有pH6.5較適合。當氣溫高於或等於木屑包溫時，則微生物量較少，反之木屑包溫高於氣溫時，則微生量較多。不論木屑包在何種pH值，若以98℃，8小時殺菌之處理時，香菇的產量或品質均優於用121℃ (151b/in^2)，90分之殺菌方式。後者之殺菌方式除了可殺滅害菌外，其它有益微生物也一併殺死，而pH 5及pH 6則在產量及菇質方面均優於pH 7。

關鍵字

香菇 ； 栽培 ； 微生物 ； 生產

並列摘要

Contamination has been a major problem for the shiitake production in Taiwan. To eliminate the contamination to a level as low as possible is very important. In this study, the contaminated microorganisms were identified and the sources of contaminants in the sawdust, spawn, inoculation and incubation rooms, and cultivation yard were described. Attempts were also made to explore the effects of the contaminants on the mycelial growth and/or the yield of shiitake. The effect of medium pH values on the mycelial growth of shiitake and contaminants were also reported. Results indicated that species of Trichoderma, Penicillium, Neurospora and Aspergillus were the most frequently isolated fungi from the sawdust spawn, while Trichoderma, Bacillus and Aspergillus were often isolated in the wheat grain spawn. The mycelium of shiitake grew more quickly in the wheat grain medium than it did in the sawdust medium. More microorganisms were trapped in the cultivation yard than in the incubation room. Unused sawdust piled outdoor for 6 months contained more microorganisms than the cultivating one. During marketing or transporting process, population of microorganisms on the surfaces of shiitake fruiting bodies increased greatly. Less amount of microorganisms were found in the normally grown sawdust than in the contaminated sawdusts. The pH value of contaminated sawdust was higher than the normal one, but not much difference was observed in the water contents of the two kind of sawdusts. The pH value of Castanopsis hytrix saw-dust was very low within 2 months of piling, but it gradually increased with time and reached ca. 6.0 within 3-4 months which will be suitable for medium perparation. The pH values of Acacia confusa and broad leaf trees also increased during piling. The mycelia of shiitake grew best in the acidic conditions when the pH value was between 4.5 and 6.0, while Trichoderma grew very well in almost all tested pH values except 7.5 The growth of Neurospora was relatively slow in all pH values with pH 6.5 as the most suitable one. When the air temperature was equal to or greater than that of sawdust, less microorganisms were found in the sawdust, however, when the air temperature was lower, more microorganisms were found. In spite of pH values, more shiitake mushrooms were produced in the sawdust medium pasteurized 8 hrs at 98℃ than that autoclaved 90min. at 121℃ (151b/in^2). The quality of shiitake mushrooms harvested from the former was also better than those form the latter. In the pasteurized medium, yields of the medium with pH values at 5 and 6 were higher than those of the medium with pH 7. Autoclaving completely killed the microorganisms in the sawdust medium while pasteurization only killed those harmful ones.

並列關鍵字

Shiitake ； Cultivation ； Microorganism ； Production