| Various flocculants are widely used in industrial and food applications such as waste water treatment, aggregation of cells and cell debris in fermentation industries, etc. Although the organic and inorganic synthetic flocculants are cost-effective and high flocculating activity, they are not easily degraded in nature. Some of them, especially polyacrylamides, contain acrylamide monomers which are both neurotoxic and strong human carcinogenic. Moreover, aluminium, a major component of poly (aluminium chloride), also induces Alzheimer's disease.Bioflocculants are polymers produced by microorganisms during their growth, which can make colloids, cells, cell debris, etc., aggregate and settle. It is a new-type, effective, low-cost water treatment reagent. In concrast with traditional organic synthetic high-mass polymer, it can be nontoxic, harmless and without secondary pollution. With the arousing of environmental consciousness, the studies of bioflocculant have attracted wide attentions.An effective bioflocculant-producing strain was first isolated from a deep-sea sediment sample of the weast Pacific Ocean. It was identified belonging to the genus Halomonas, but differentitated from other described Halomonas species, according to its physiological and biochemical chatracteristics and 16S rDNA sequence. Therefore, a novel species, was proposed with the strain No. V3a. The result indicated that bioflocculant was released into the culture and its production was growth-related. The optimal growth temperature was 23℃, but the optimal temperature for flocculant production was 18℃. The culture was very mucoid and 200μl of culture into 100ml Kaolin clay suspension (0.5g) resulted in 97% flocculating rate. Glucose and NH4Cl were the most appropriate carbon and nitrogen sources, respectively. The highest yield was obtained at the C/N ratio of...
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