本土固氮菌與光合菌的分離鑑定暨特性研究並評估對作物生長促進的效果

可促進植物生長之根圈微生物 (plant growth-pomoting rhizobacteria, PGPR) 已被證明可以有效改良土壤的理化性質，促進作物生長、減少病害，進而達到增加收量與提高品質的效果。本研究的目的，是要從台灣各地的農耕地中分離具有應用潛力的固氮菌群以及光合菌群，進而開發出能促進肥效、提高作物產量以及增強抗逆境等功能的微生物製劑。固氮菌的分離方式採用優勢培養，再結合分子快速篩選法從土壤菌中挑選具有固氮能力的菌株；光合細菌則是利用Winogradsky土壤管柱進行分離。各菌株的身份鑑定採用分子生物學的方法，根據各菌株的 16S rDNA 序列，與 NCBI 的 GeneBank 資料庫做相似度比對以判定菌種分類。所分離的 30 株固氮菌，分屬於Azotobacter、Azospira、Bacillus、Burkholderia、Pseudomonas、Sphingomonas、Acidovorax、Klebsiella 8個屬；10株光合菌則皆為 Rhodopseudomonas 屬。利用作物生長平台從分離菌株中挑選出下列八株具促進植物生長潛力的菌株： Azotobacter chroococcum YSE1、Azotobacter chroococcum YSE6、 Azospira sp.TPP4、Pseudomonas stutzeri YSC3C、 Bacillus sp. YSC4C、 Rhodopseudomonas palustris PS3、Rhodopseudomonas palustris YSC3、Rhodopseudomonas palustris YSC4。經由生理生化試驗，確認各潛力菌株的碳源利用、酵素活性、最適生長條件（溫度、酸鹼、鹽濃度）、固氮活性、植物生長激素 (吲哚乙酸) 生成能力以及溶磷能力。在小白菜盆栽試驗中，發現施用光合菌PS3菌肥的處理組可使植株的鮮重與乾重等農藝性狀達到與施用全量化肥同等水準。在水稻盆栽試驗中，發現施用 TPP4、YSC4C 以及 PS3 潛力菌肥的處理組，其營養生長期的株高與開花後的劍葉葉色值（SPAD值）皆較施用全量化肥組高。水稻農藝性狀分析結果顯示，以單株菌株TPP4取代半量慣型化肥用量組之榖粒產量高於全量慣行化學肥料組，同時可維持榖粒完整率。

關鍵字

促進植物生長根圈微生物；微生物肥料固氮菌；光合菌

並列摘要

Plant growth promoting rhizosphere bacteria (PGPR) has been shown to improve soil physical and chemical properties, increase growth of plants, and reduce plant diseases. The purposes of this study were to isolate and screen for nitrogen-fixing and photosynthetic bacteria from Taiwan agricultural lands and test for their biofertilizer potential. Bacteria that survived in N-free minimal medium and possessed the nitrogenase activity were selected as nitrogen-fixing bacteria. Photosynthetic bacteria were isolated by the Winogradsky method. All forty isolates were identified by 16S rDNA sequencing and phylogenetic analysis. Thirty isolates were belonged to eight genera, including Azotobacter, Azospira, Bacillus, Burkholderia, Pseudomonas, sphingomonas, Acidovorax, and Klebsiella; and ten strains classified to the genus Rhopseudomonas. Eight potential strains (TPP4,YSE1,YSE6,YSC3C, YSC4C, PS3, YSC3, YSC4) were screened from the isolates by using plant growth promoting tests. Their optimum growth conditions (including temperature, pH, and saintily), nitrogenase activity, phosphorus-solubilizing ability, and plant hormone auxin (indole-3-acetic acid, IAA) production ability were further examined by various physiological and biochemical assays. The potential strains were used as inoculants in pot experiments. Application of the photosynthetic bacteria (PS3) inoculant significantly improved plant height, plant fresh weight, and plant dry weight of Chinese cabbage. In addition, significant increases in shoot length and SPAD value of flag leaves were observed while the potential strains (PS3, TPP4 and YSC4C) were used as inoculants for cultivation of rice. According to analysis of agronomic traits, application of the nitrogen-fixing bacteria (TPP4) inoculant significantly improved the yield and quality of rice grain under 50% chemical fertilizer treatment.

並列關鍵字

Plant growth promoting rhizosphere bacteria ； Biofertilizer ； nitrogen-fixing bacteria ； photosynthetic bacteria

參考文獻

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本土固氮菌與光合菌的分離鑑定暨特性研究並評估對作物生長促進的效果

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