Characterization of a bioflocculant produced by the marine myxobacterium Nannocystis sp. NU-2

Abstract

The marine myxobacterium strain NU-2, which can grow on high concentrations (up to 7%) of NaCl, was isolated from a salt soil sample collected from the coast of the Huanghai Sea, China. Morphological properties and 16S rDNA sequence analysis indicated that the isolate is a novel species related to the genus Nannocystis. Nannocystis sp. NU-2 produced a new kind of flocculating substance in a starch medium with a yield of 14.8 g l(-1). The NU-2 flocculant was composed of 40.3% proteins and 56.5% polysaccharides, of which glucose, mannose and glucuronic acid were the principal constituents in the relative proportions of 5:4:1. The flocculation activity of the NU-2 flocculant depends strongly on cations such as Fe(3+) and Al(3+). When a 30 mg l(-1) FeCl(3) solution is present in kaolin clay suspension, 30 mg l(-1)of the flocculant produced a high flocculating activity value of 90%, which remained unchanged over an extensive pH range (pH 2.0-13.0). The flocculant was tested for its ability to bleach dyeing liquors, and the bleaching activities were 98.2% for acid red in 100 mg l(-1)of the flocculant and 99.0% for direct emerald blue in 50 mg l(-1)of the flocculant under test conditions. Use of the flocculant to bleach basic pink and cation emerald blue liquors was not effective.

Assessment of Bioflocculant Production by Bacillus sp. Gilbert, a Marine Bacterium Isolated from the Bottom Sediment of Algoa Bay

“…A number of bioflocculants have been documented and the majority have been found to contain major components such as polysaccharides, proteins, lipids, glycolipids and glycoproteins [29,30]. The bioflocculant produced by our test bacterium was found to be mainly polysaccharide with the total sugar concentration of 22.5 mg/mL, and no protein was detected.…”

Microbial flocculation, a potentially low-cost harvesting technique for marine microalgae for the production of biodiesel

“…Therefore, the methods described by these reports are not suitable for harvesting microalgae for low-cost commodities such as biodiesel. Furthermore, many of the results described are also not applicable in a marine environment (Zhang et al 2002).…”

Characterization and flocculating properties of a novel bioflocculant produced by Bacillus circulans

“…The bioflocculant p-KG03 was reported to be active at acidic conditions (pH 3-6) (Yim et al 2007), while the bioflocculant of Nannocystis sp. NU-2 was active in alkaline conditions ranging from pH 12-14 in the presence of 30 mg/l CaCl 2 Á2H 2 O (Zhang et al 2002). The flocculant from Streptomyces griseus was active in acidic conditions ranging from pH 2-6, with the maximum activity observed at pH 4 (Shimofuruya et al 1996).…”