餵食短小芽孢桿菌對白蝦成長促進與免疫調節之影響研究

Studies on the effect of dietary Bacillus pumilus on growth performance and immune modulation in white shrimp (Litopenaeus vannamei)

陳昱安(Chen Yu-An)

指導教授 ： 胡紹揚

國立屏東科技大學/農學院/生物科技系/碩士(2019年)

https://doi.org/10.6346/NPUST201900258

摘要

本研究由吳郭魚腸道分離出一株產蛋白酶、纖維素酶和木聚糖酶之菌株，經由16S rDNA序列分析後，確認此菌株為短小芽孢桿菌 (Bacillus pumilus)。為了評估B. pumilus作為養殖益生菌潛力，分別在飼料中添加1 x 106 CFU/g和1 x 107 CFU/g餵食白蝦2個月，分析對南美白蝦的生長促進、改善腸道酵素活性、免疫指標和腸道菌相功效，結果顯示餵食1 x 106 CFU/g組，在體重增加和飼料效益上都顯著高於控制組和1 x 107 CFU/g組。在腸道酵素活性方面，有餵食益生菌的組別，在腸道中雖有較高之酵素活性，但與控制組結果相較並沒有顯著差異。免疫指標方面餵食B. pumilus組別在酚氧化酶活性、吞噬活性、呼吸爆活性和溶菌酶活性顯著高於控制組，以溶藻弧菌注射感染白蝦，感染7天後結果顯示，餵食B. pumilus的組別存活率顯著高於控制組，以real-time PCR分析免疫相關基因，結果顯示餵食1 x 106 CFU/g的組別，免疫基因的表現皆顯著高於控制組，1 x 107 CFU/g的組別除Crustin基因，其餘的基因皆高於控制組。NGS結果顯示餵食B. pumilus有助於提高腸道的菌種多樣性，而餵食1 x 106 CFU/g在菌種分類族群的相對豐富度數量上高於其餘兩組。綜合以上結果說明短小芽孢桿菌 (B. pumilus)具有潛力作為益生菌，應用於白蝦養殖的成長促進、改善免疫調節、腸道菌相與疾病抵抗。

關鍵字

益生菌 ； 短小芽孢桿菌 ； 南美白蝦 ； 免疫指標

並列摘要

In the present study, a strain with protease, cellulase and xylanase activity was isolated from the intestine of tilapia and characterized as Bacillus pumilus by 16S rDNA sequencing analysis. In order to evaluate B. pumilus as a probiotic to promote the growth, intestinal enzyme activity, immune index and intestinal flora of white shrimp (Litopenaeus vannamei). White shrimp was fed with diet containing 1 x 106 CFU/g and 1 x 107 CFU/g of B. pumilus for eight weeks. The results showed that the 1 x 106 CFU/g group was significantly higher in weight gain and feed efficiency than the control group and 1 x 107 CFU/g group. Although the intestinal hydrolytic enzymes activities were higher in probiotic fed fish than those in control fish, but there were no significant differences between each group. The phenoloxidase activity, phagocytic activity, respiratory burst activity and lysozyme activity were higher in fish fed control diet containing B. pumilus than those fish fed control diet. Challenged test showed that the survival rate of B. pumilus fed shrimp was higher than those of fish fed control diet. Real-time PCR results showed that the mRNA expression of immune genes, such as Penaeidin-3a, lysozyme, Prophenoloxidase, TGase and LvALF1 genes, were significantly increased in white shrimp fed B. pumilus. The NGS results showed that feeding of B. pumilus increase the diversity of the intestinal flora in white shrimp. The relative abundance of the intestinal flora in shrimp fed with 1 x 106 CFU/g of B. pumilus was higher than that in control and 1 x 107 CFU/g groups. These results elucidated that B. pumilus has potential to be used as probiotic to enhance growth performance, immune modulation and disease resistance in white shrimp aquaculture.

並列關鍵字

probiotics ； Bacillus pumilus ； white shrimp ； immune modulation

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