Characteristics and flocculating mechanism of a novel bioflocculant HBF-3 produced by deep-sea bacterium mutant Halomonas sp. V3a’

Abstract

A novel bioflocculant HBF-3 produced by deepsea bacterium mutant Halomonas sp. V3a' was investigated with regard to its flocculating characteristics and mechanism. 4.0 m g l -1 HBF-3 showed the maximum flocculating activity of 96.9% in 5.0 g l -1 Kaolin suspension containing 11.25 mM CaCl 2 , and that its flocculating activity was more than 90% within 5-40°C and over 80% in a wide pH range (3.0-11.0). Chemical analyses indicated that the biopolymer HBF-3 was mainly a polysaccharide, including neutral sugar residues (20.6%), uronic acid residues (7.6%), amino sugar residues (1.6%) and sulfate groups (5.3%). Fourier transform infrared (FTIR) spectrum showed the presence of carboxyl and hydroxyl groups in HBF-3 molecular. The average molecular mass of HBF-3, as determined by gel filtration chromatography (GFC), was approximately 590 kDa. Flocculation of Kaolin suspension with HBF-3 acted as a model to explore the flocculating mechanism in which bridging mediated by Ca 2? was proposed as the primary action based upon the experimental observations.

Production and characteristics of bioflocculant TPT-1 from a consortium of Bacillus pumilus JX860616 and Alcaligenes faecalis HCB2

“…Based on these results, it was concluded that Ba , forming bridges that aggregated Kaolin particles together. Ba 2+ compacted the double layer of Kaolin particles, deteriorated the static repulsive force between Kaolin particles and reduced the distance between Kaolin particles and the functional groups of TPT -1 (He et al, 2010). The observations were similar to those of Song et al (2014), whereby the bridging mechanism was concluded as the main flocculation mechanism of bioflocculant ETH-2.…”

“…Lu et al (2005) reported that cations have significant effect on flocculation. Cations are used as coagulant aids in achieving high flocculation activities by neutralizing the negatively charged functional groups of bioflocculants and suspended particles, thereby increasing the adsorption of bioflocculants to the suspended particles (He et al, 2010). The stimulating effect of cations in flocculation is dependent on the concentration of the cations as well as the valence ions .…”

Assessment of Bacillus pumilus Isolated from Fresh Water Milieu for Bioflocculant Production

“…The bioflocculant was ground with KBr salt at 25˝C and pressed into a pellet for FTIR spectroscopy over a wave number range of 4000-370 cm´1 [27].…”

“…The desired bioflocculant concentration was added to each flask and the flocculating activity was measured as previously described [27].…”

Studies on Bioflocculant Production by Bacillus sp. AEMREG7

“…Depending on specific environmental conditions, microbes can be manipulated to produce exopolymeric substances of a particular composition, and physiochemical properties that promote the survival of the microbial population [31]. Nonetheless, marine environments have been documented supplying interesting bacteria-producing unique bioactive compounds such as bioflocculants that have various industrial applications [32].…”