從養豬場廢水中分離鑑定微藻並探討藻體優化方式及潛力分析

Abstract

藻類是個含有大量族群的物種，依其形狀大小可以再分成巨藻以及微藻，其可以在淡水、海水甚至是廢水中生存，本研究從台灣的養豬場廢水中分離出16株微藻，並搭配分子鑑定以及親源演化將其命名，分別有Chlorella sorokiniana、Micractinium sp.、Chlorellaceae sp.以及四組Chlorella sp.共七組，其中8株藻可能為新種，1株藻可能為新屬，並命名為Chlorellaceae sp. strain P5且對其做深入研究。微藻根據其藻體的功能可以利用空氣中二氧化碳行光合作用生長，也可以藉由液體中的碳源以異營的方式生長，Chlorellaceae sp. strain P5除了可以生長在20℃到40℃的環境中，適應pH4到pH9的環境、耐受0%到3%的鹽度外，也可以利用異營方式生長，雖然自營培養所花費的成本較低，但是藻體產量卻很低，且其培養時間比異營培養要來的長，因此利用異營的方式進行培養，並且以反應曲面法優化後發現其藻體產量可達到1.615±0.047 g/L/day，為自營培養的61.877倍。近年來微藻被視為生質能源的新材料，因為其產量較經濟作物高，且具有低成本、高能量以即可完全利用的特點，此外部分微藻含有高含量的胺基酸，可以應用於動物飼料的添加。另一方面，農業廢水含有較高濃度的有機物，如硝酸氮、氨氮以及磷酸鹽，這些將導致環境問題產生。我們發現Chlorellaceae sp. strain P5其脂肪酸組成主要為C16以及C18，這些也是可用於生質柴油的主要脂肪酸，而其胺基酸組成多元並且具有成為添加於動物飼料的潛力，而Chlorellaceae sp. strain P5可於稀釋2倍及4倍的養豬場排放水中生長，並且在培養1週後可移除80%的硝酸氮、98%的氨氮以及46%的磷酸鹽。

Microalgae are large groups that can be found in sea, freshwater even in wastewater, they can divide into “Macroalgae” and “Microalgae” which based on their size. The study got wastewater from three pig farms and selected sixteen microalgae strains, we gave them name after molecular identification and phylogenetic tree. They are Chlorella sorokiniana, Micractinium sp., Chlorellaceae sp. and four groups Chlorella sp.; we found there are 8 strains might be new species and 1strain might be a new genus which named Chlorellaceae sp. strain P5 and we chose it as our potential microalgae. Microalgae can grow in phototrophy or heterotrophy which depends on their function, we found Chlorellaceae sp. strain P5 can grow in wild range at 20℃to 40℃, adapt to pH4 to pH9 and tolerate 0% to 3% salinity, most importantly, it can grow in heterotrophic medium. Although phototrophy has least cost, the biomass is lower and the culture time is too long than heterotrophy. We found P5strain biomass prodictivity can raise from 0.0261±0.003 to 1.615±0.047 after culture from photoprophy to optimized heterotrophy and it increased 61.877 fold. In recent years, microalgae are as a new source of biofuel, because they provide higher biomass than comparable energy crops and act as a low-cost, high-energy and entirely renewable feedstock; some microalgae might contain higher amino acid that can add to animal feed. On the other hand, livestock wastewater contain high level inorganic matter, like nitrogen and phosphorous concentrations, these can cause severe environmental problems. The main fatty acids in Chlorellaceae sp. strain P5 are C16 and C18, these also main fatty acid used in biodiesel; the amino acid compositions are multivariate, and it had potential add to animal feed; Chlorellaceae sp. strain P5 also can grow in diluted twice and fourfold piggery drainage tank wastewater, it can remove 80% nitrate, 98% ammonia and 46% phosphorus after cultured 1 week.