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Highlights: [•] The bioflocculant-producing bacteria isolated from a sputum sample. [•] The bioflocculant is stable at wide ranges of pH and temperature. [•] Cation-independent bioflocculant produced by Klebsiella pneumoniae. [•] It could flocculate a variety of real wastewaters. [•] 79.4% flocculating activity for amoebae cysts was achieved with the bioflocculant. [ABSTRACT FROM AUTHOR]

This study aimed to isolate a novel archaeon capable of simultaneously producing methane and bioflocculants. The isolated methanogen was identified as Methanosarcina spelaei RK-23 by molecular characterization. Strain RK-23 grew with different carbon sources, but acetate was found to be the most beneficial carbon source for the production of methane and bioflocculants. Moreover, RK-23 produced methane and bioflocculants within an initial pH range of 5.0–8.0, with an optimal pH for methane production of 6.5 and flocculating activity of 7.0. In addition, strain RK-23 exhibited tolerance to high-salinity conditions and produced methane and bioflocculants within 0–1.2 M NaCl, with an optimum NaCl concentration of 0.3 M. The methane production and flocculating activity of strain RK-23 under optimal culture conditions were 17.4 mmol methane/mol acetate and 95.6%, respectively. MBF-23 mostly consisted of 83.5% carbohydrates and 14.3% proteins. Furthermore, the bridging of adsorption is believed to be the main bioflocculation mechanism in this study. • A novel bioflocculant-producing methanogen, Methanosarcina spelaei RK-23, was isolated. • RK-23 converted acetate to methane and MBF-23. • RK-23 secreted methane and MBF-23 within a wide salinity range. • MBF-23 was negatively charged, with a molecular weight of 3.5 × 106 Da. [ABSTRACT FROM AUTHOR]

Bioflocculants are widely used in a large variety of applications, because of their wide range of flocculation. There is limited information in the literature about the ability of bioflocculants to perform beneficial functions without having adverse effects on blood components. In this study, general hemocompatibility of a bioflocculant (MBF-06) was investigated in an in vitro system, measuring flocculation of plasma proteins, red blood cell integrity, blood cell counts, platelet activation, clot formation, complement activation, cytotoxicity and inflammatory response. Effects of MBF-06 included low plasma protein flocculation, low platelet activation, low inflammatory response, no hemolysis or cytotoxicity and increased expression of coagulation markers, including prothrombin fragments 1 + 2. These findings suggested that the rapid hemostasis caused by MBF-06 resulted, essentially, from humoral coagulation. Overall, our observations revealed the great potential of MBF-06 as a novel hemostatic agent. [ABSTRACT FROM AUTHOR]

Bioflocculants have been applied in numerous applications including heavy metals removal. A major bottleneck for commercial application of bioflocculant is its high production cost. Phenol-containing wastewater are abundantly available. However, the toxic phenol inhibited the microbial activities in the subsequent fermentation processes. Consequently, strains that can secrete phenol-degrading enzymes and simultaneously produce bioflocculants through directly degrading the phenol are of academic and practical interests. A phenol-degrading strain, Stenotrophomonas maltophilia ZZC-06, which can produce the bioflocculant MBF-06 using phenol-containing wastewater, was isolated in this study. The effects of culture conditions including initial pH, dissolved oxygen, phenol concentration, inoculum size, and temperature on MBF-06 production were analyzed. The experimental results showed that over 90% flocculating activity was achieved when the phenol was used as a carbon source and 4.99 g/L of MBF-06 was achieved under the optimized condition: 2.0% dissolved oxygen, 800 mg/L phenol concentration, 10% inoculum size, an initial pH of 6.0, and a temperature of 30 °C. The bioflocculant MBF-06 contained 71.2% polysaccharides and 27.9% proteins. The feasibility of cadmium removal using MBF-06 was evaluated. The highest flocculating efficiency for cadmium was 81.43%. This study shows for the first time that Stenotrophomonas maltophilia ZZC-06 can directly convert phenol into a bioflocculant, which can be used to effectively remove cadmium. [ABSTRACT FROM AUTHOR]

A novel bioflocculant (MBF83) prepared using methanol wastewater as nutrient resource was systematically investigated in the study. The optimal conditions for bioflocculant production were determined to be an inoculum size of 8.6%, initial pH of 7.5, and a methanol concentration of 100.8 mg L −1 . An MBF83 of 4.61 g L −1 was achieved as the maximum yield. MBF83 primarily comprised polysaccharide (74.1%) and protein (24.2%). The biopolymer, which was found to be safe in zebrafish in toxicity studies, was characterized using Fourier-transform infrared spectroscopy and elemental analysis. Additionally, conditions for the removal of arsenite by MBF83 were found to be MBF83 at 500 mg L −1 , an initial pH of 7.0, and a contact time of 90 min. Under the optimal conditions, the removal efficiency of arsenite was 86.1%. Overall, these findings indicate bioflocculation offers an effective alternative method of decreasing arsenite during wastewater treatment. [ABSTRACT FROM AUTHOR]

A novel strain (designated as ZCY-7) which could convert H-acid into bioflocculants was isolated from H-acid wastewater sludge. Conditions for bioflocculants production were optimized by response surface methodology (RSM) and determined to be inoculum size 9.65%, initial pH 7.0, and COD Cr of the H-acid wastewater 520 mg/L. The highest flocculating efficiency achieved for kaolin suspension was 95.1%, after 60 h cultivation. The yielded bioflocculant was mainly composed of polysaccharide (82.4%) and protein (14.2%), and maintained its flocculating activity in 0.4% (w/w) kaolin suspensions over pH 2–8 and 20–80 °C. Fourier transform infrared (FTIR) spectra showed that amino, amide and hydroxyl groups were present in the bioflocculant molecules. A viable alternative treatment technology of H-acid wastewater using this novel strain is suggested, which could largely reduce bioflocculants costs. In addition, flocculating mechanism investigation reveals that the bioflocculant could cause kaolin suspension instability by means of charge neutralization firstly and then promoted the aggregation of suspension particles by adsorption and bridge. It is evident from the results that H-acid wastewater could be used as a source to manufacture bioflocculants. [ABSTRACT FROM AUTHOR]

High cost is one of the limiting factors in the industrial production of bioflocculant. Simultaneous preparation of bioflocculant from the contaminants in wastewater was considered as a potential approach to reduce the production cost. In this study, caprolactam was verified as sole feedstock for the growth of strain Alcaligenes faecalis subsp. phenolicus ZY-16 in batch experiments. Chemical analysis showed that the as-prepared MBF-16 consisted of heteropolysaccharides (88.3%) and peptides (9.4%). XPS result indicated the plentiful acylamino, hydroxyl and amino groups in MBF-16, which have an indispensable role in amoxicillin flocculation. The flocculation of amoxicillin can be well stimulated by Freundlich isotherm equation, and the K f was up to 178.6524 for amoxicillin. The kinetic fitting results proved that the flocculation of amoxicillin by MBF-16 was chemisorbed. This contribution may develop a novel technology for the preparation of bacterial flocculants that can consume toxic substrates (caprolactam) and have potential applications in amoxicillin removal. • Caprolactam could be an available feedstock to produce bioflocculants. • Hydroxyl, amino and acylamino groups are abundant in the bioflocculant. • Cation-independent flocculant is produced by Alcaligenes faecalis. • Chemisorption is involved in amoxicillin and the bioflocculant. [ABSTRACT FROM AUTHOR]