BACKGROUND Understanding about the impact of white rot fungi on indigenous bacterial communities, NH4+ and turbidity in digested piggery wastewater, will allow the optimization of wastewater treatment methods and its use as a feasible medium for algal growth. Here, the white rot fungi were inoculated into undiluted and unsterilized digested piggery wastewater under different temperatures and pH regimes in order to lower the pretreatment cost. Diversity and abundance of the bacterial communities in the pretreated wastewater were assessed by PCR-denaturing gradient gel electrophoresis coupled with 16S rDNA sequencing. RESULTS The research showed a significant reduction on the microbial diversity with the presence of white rot fungi which occur at pH 6. The distribution and presence of bacteria taxa were strongly correlated with NH4+ concentration, pH, and the presence of white rot fungi. Variance partition analysis also showed that the effect on the chlorophyll content of algae in fungi-filtered wastewater was as the following hierarchy: bacterial diversity > NH4+ > turbidity. Therefore, the algae in treated wastewater with less abundance of bacteria proliferated more successfully, indicating that bacterial community not only played an important role in algal growth but also imposed a strong top-down control on the algal population. The algae grown in wastewater treated with fungi reached the highest specific growth rate (0.033 day-1), whereas the controls displayed the negative specific growth rate. The fatty acid composition varied markedly in C16:0 and C18:0 between these treatments, with a higher content of C16:0. CONCLUSIONS This study firstly showed that Chlorella can grow as cost-effective biofuel feedstocks in undiluted and unsterilized digested wastewater with high ammonium concentration and dark brown color because the bacterial abundance of digested piggery wastewater could be reduced greatly by the white rot fungi.

中文翻译：

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对生猪消化废水进行真菌预处理，提高藻类作为生物燃料原料的存活率。

背景了解白腐真菌对消化养猪废水中本地细菌群落、NH4+和浊度的影响，将有助于优化废水处理方法及其作为藻类生长的可行介质的用途。在此，为了降低预处理成本，将白腐真菌在不同温度和 pH 条件下接种到未稀释和未灭菌的消化养猪废水中。通过 PCR 变性梯度凝胶电泳结合 16S rDNA 测序评估预处理废水中细菌群落的多样性和丰度。结果 研究表明，pH 6 时，白腐真菌的存在会显着降低微生物多样性。细菌类群的分布和存在与 NH4+ 浓度、pH 值和白腐真菌的存在密切相关。方差分配分析还表明，菌类过滤废水中藻类叶绿素含量的影响顺序为：细菌多样性>NH4+>浊度。因此，经过处理的废水中细菌丰度较低的藻类增殖更成功，表明细菌群落不仅在藻类生长中发挥着重要作用，而且对藻类种群具有强大的自上而下的控制作用。在经过真菌处理的废水中生长的藻类达到了最高的比生长率（0.033 day-1），而对照组则显示出负的比生长率。这些处理之间的脂肪酸组成在C16:0和C18:0方面显着变化，其中C16:0含量较高。结论本研究首先表明，小球藻可以作为具有成本效益的生物燃料原料在未稀释和未灭菌的高铵浓度和深棕色消化废水中生长，因为白腐真菌可以大大降低消化养猪废水的细菌丰度。