title: Experimental study using the dilution incubation method to assess water biostability.
abstract: Water biostability is of particular concern to water supply as a major limiting factor for heterotrophic bacterial growth in water distribution systems. This study focused on bacterial growth dynamics in the series dilution of water samples with TOC (total organic carbon) values determined beforehand. The results showed that the specific growth rate of Pseudomonas fluorescens P17 varied dramatically and irregularly with TOC value when TOC concentrations were low enough during the initial periods of incubation under given conditions. According to this relationship between bacterial growth rate and TOC, a dilution incubation method was designed for the study of water biostability. With the method under a given condition, a turning-point TOC value was found at a relatively fixed point in the curve between bacterial growth rate and TOC of water sample, and the variation of growth rate had different characteristics below the turning-point TOC value relative to that over this value. A turning-point TOC value similarly existed in all experiments not only with tap water, but also with acetate and mixed solutions. And in the dilution incubation method study, the affections were analyzed by condition factors such as inoculum amount, incubation time and nature of the organic carbon source. In very low organic carbon water environments, the variation characteristics of bacterial growth rate will be useful to further understand the meaning of water biostability.
authors.affiliation: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China. Electronic address: 2011qhwang@tongji.edu.cn.
authors.forename: Qiuhua
authors.initials: Q
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
authors.affiliation: College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: xkl@tongji.edu.cn.
authors.forename: Kunlun
authors.initials: K
authors.lastname: Xin
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D001419:Bacteria / Q000254:growth & development; D019346:Sodium Acetate / Q000737:chemistry; D014867:Water; D014871:Water Microbiology
chemical_list: D014867:Water; D019346:Sodium Acetate; D000255:Adenosine Triphosphate
keywords: Bacterial growth rate; Dilution incubation method; Heterotrophic bacteria; Total growth organic carbon; Water biostability