光合菌潛力菌株-Rhodopseudomonas palustris NTUIOB-PS3之劑型配方研究

Abstract

微生物肥料具有改善土壤理化性質，幫助植物吸收養分以及維持健康的特性，可以減少農化產品的施用，被視為一種對環境友善的施肥方式，可兼顧到農作豐產與自然生態平衡。為了將潛力菌株開發成為具商品價值的微生物製劑，如何藉由適當的製劑配方使得產品在儲架期間能保有最高的活菌數遂成為重要課題。Rhodopseudomonas palustris NTUIOB-PS3為分離自台灣水田土壤的光合菌株，它不僅對作物具顯著的生長促進功效，還可提昇植物代謝化學肥料的效率。本研究的目的是要尋找出適合PS3菌株的液態/固態劑型配方與儲存條件。PS3 光合菌分別與六種液態劑型添加物 (褐藻酸鈉、聚乙二醇、聚乙烯比如烷酮、甘油、葡萄糖、礦物油) 以及五種固態劑型載體 (泥炭土、蛭石、稻殼、甘蔗渣、菜仔粕) 進行加工，並儲存於4°C、25°C、37°C條件下一個月，經由平板菌落計數估算殘存活菌數。實驗結果發現礦物油是最適合做為液態劑型添加劑，泥炭土則是固態劑型的最適載體。經評估兩種劑型之生產加工程序、設備成本、產品儲架壽命、雜菌控制難易度以及對施用環境的影響等要素，液態劑型配方對於PS3菌株而言應是較為適合的加工方式。添加0.5%的礦物油至PS3發酵液即可顯著提昇菌株在儲架期間的殘存活菌數。在小白菜盆栽試驗中發現經由該方式加工的製劑在不同溫度下儲存一個月後依然能有效促進作物生長，與未加工的對照組相較其鮮乾重分別增加了35-70%、50-90%不等程度。由於礦物油本身屬於安全農業資材，而且成本低廉，加工簡易，該製劑技術將有利於 PS3光合菌的商品化與實用性。

Biofertilizers can help to improve soil quality, promote growth of crops, and sustain soil health. Therefore, such approach to farming is regarded as environmental friendly, and can be used to reduce excessive amount of chemical fertilizer application, and ensures a sustainable crop production. To put the embryonic form of elite microbial isolate from bench to practical use, product development and formulation is needed to maintain high quality of the inoculant during storage. A photosynthetic bacterium, Rhodopseudomonas palustris strain NTUIOB-PS3 was isolated from Taiwanese paddy soil, which could not only exert beneficial effects on plant growth, but also enhance the efficiency for up taking applied fertilizer nutrients. The aim of this study was to select suitable processing condition and formulation in improving the quality of PS3 inoculant. Six additives (alginate, PEG, PVP, glycerol, glucose, mineral oil) and five carriers (peat, vermiculite, rice husk, sugarcane bagasse, rapeseed meal) were used for liquid and solid-based formulations, respectively. The capacity of these materials for maintaining PS3 cell viability during storage at 4°C, 25°C and 37°C was evaluated. On the basis of the survival rate of PS3 cells, mineral oil and peat were chosen to be candidate materials for liquid and solid based formulations, respectively. In consideration of manufacturing process, cost, shelf life, contamination issue, and environmental concerns, etc., liquid-based formulation seems more appropriate for manufacturing PS3 inoculant. Accordingly, mineral oil (0.5%) was chosen as the potential additive candidate for liquid-based formulation according to the survival rate of PS3 cells during storage. In addition, the growth-promoting effects of Chinese cabbage exerted by this formulated inoculant under one-month storage at 4°C, 25°C and 37°C were more significant than those of the non-formulated treatments. Shoot fresh and dry weights were significantly increased at 35-70% and 50-90%, respectively. Due to mineral oil is considered as a safe, low cost, and easy-to-process agricultural material, this formulation technology will facilitate the commercialization and practical use of PS3 inoculant. Key words: Plant growth promoting rhizobacteria (PGPR), biofertilizer, formulation, Rhodopseudomonas palustris, shelf life