Pagilla K R, Sood A, Kim H
Chemical and Environmental Engineering Department, Illinois Institute of Technology, Chicago 60616, USA.
Water Sci Technol. 2002;46(1-2):519-24.
Gordonia amarae, a filamentous actinomycete, commonly found in foaming activated sludge wastewater treatment plants was investigated for its biosurfactant production capability. Soluble acetate and paringly soluble hexadecane were used as carbon sources for G. amarae growth and biosurfactant production in laboratory scale batch reactors. The lowest surface tension (critical micelle concentration, CMC) of the cell-free culture broth was 55 dynes/cm when 1,900 mg/L acetate was used as the sole carbon source. The lowest surface tension was less than 40 dynes/cm when either 1% (v/v) hexadecane or a mixture of 1% (v/v) hexadecane and 0.5% (w/v) acetate was used as the carbon source. The maximum biomass concentration (the stationary phase) was achieved after 4 days when acetate was used along with hexadecane, whereas it took about 8 days to achieve the stationary phase with hexadecane alone. The maximum biosurfactant production was 3 x CMC with hexadecane as the sole carbon source, and it was 5 x CMC with the mixture of hexadecane and acetate. Longer term growth studies (approximately 35 days of culture growth) indicated that G. amarae produces biosurfactant in order to solubilize hexadecane, and that adding acetate improves its biosurfactant production by providing readily degradable substrate for initial biomass growth. This research confirms that the foaming problems in activated sludge containing G. amarae in the activated sludge are due to the biosurfactant production by G. amarae when hydrophobic substrates such as hexadecane are present.
戈登氏菌，一种丝状放线菌，常见于活性污泥泡沫废水处理厂，对其生物表面活性剂生产能力进行了研究。在实验室规模的间歇反应器中，使用可溶性乙酸盐和微溶性十六烷作为戈登氏菌生长和生物表面活性剂生产的碳源。当使用1900mg/L乙酸盐作为唯一碳源时，无细胞培养液的最低表面张力（临界临界临界胶束临界浓度，CMC）为55达因/厘米。当使用1%（v/v）十六烷或1%（v/v）十六烷与0.5%（w/v）乙酸盐的混合物作为碳源时，最低表面张力小于40达因/厘米。当乙酸盐与十六烷一起使用时，4天后达到最大生物量浓度（稳定期），而仅使用十六烷时，大约需要8天才能达到稳定期。以十六烷为唯一碳源时，生物表面活性剂的最大产量为3×CMC，以十六烷和乙酸盐的混合物为碳源时，最大产量为5×CMC。长期生长研究（约35天的培养生长）表明，戈登氏菌产生生物表面活性剂以溶解十六烷，添加乙酸盐通过为初始生物量生长提供易于降解的底物来提高其生物表面活性剂产量。这项研究证实，活性污泥中含有戈登氏菌时活性污泥中的泡沫问题是由于存在十六烷等疏水底物时戈登氏菌产生生物表面活性剂所致。
