本研究係以中台灣高美濕地之沉積底泥中，培養出降解海藻產甲烷之中溫厭氧混合菌群。此厭氧菌群以龍鬚菜之海藻多糖為主要碳源，以批次方式培養在不同溫度、鹽度、pH值、生長輔因子(yeast extract, peptone)、碳源、不同海藻多醣來源之條件下生長。根據結果顯示此厭氧生物降解海藻產甲烷之最佳溫度、鹽度與pH值分別為35oC、0 %與pH 7.1，而最佳碳源(龍鬚菜)添加濃度為4 g/L；此外生長輔因子(yeast extract，peptone)皆有促進之結果，而以yeast extract有較佳的刺激生長作用；再由最佳條件下進行不同藻類之降解產甲烷研究，此厭氧菌群無法顯著地將馬尾藻之藻體降解，但可利用其溶出之海藻多醣，而龍鬚菜則可被降解至破碎薄片狀；以最佳化反應條件培養時，有最高之海藻降解速率為0.84±0.08 g．L-1．day-1，且可生成最高1431.20±99.65 mmole之甲烷生成，其甲烷生成速率為210.02±24.15 mmole．day-1，反應液之主要中間產物為醋酸，最高可生成29.96±1.04 mmole醋酸，產率為16.11±0.14 mmole．g seaweed-1。 Mesophilic anaerobic biodegradation of seaweed by mixed microorganisms from Kaomei wetland sediment at Central Taiwan was investigated in this study. Gracilaria was used as the sole carbon source for methane production by the mixed culture. Batches of the mixed culture were grown at different conditions such as different temperatures, sodium chlorides, pH’s, growth factors, carbon sources and various sources of algal polysaccharides from seaweed to determine the optimal conditions for methane production from seaweed bioconversion. The optimal temperature, sodium chloride concentration and pH value for bioconversion of seaweed to methane was 35oC, 0 % and pH 7.1, respectively. The optimal substrate concentration for methane production was 4 g/L of Gracilaria. Both growth factors yeast extract and peptone could stimulate bacterial growth with yeast extract giving the better effect. Sargassum could not be degraded by the mixed culture at the optimal conditions,. The highest seaweed degradation rate, methane yield and methane production rate by the mixed culture were 0.84±0.08 g．L-1．day-1, 1431.20±99.65 mmole and 210.02±24.15 mmole．day-1 respectively. Acetic was found to be the major product in the liquid phase during Gracilaria biodegradation. The highest acetate yield is 16.11±0.14 mmole．g seaweed-1.
