Related Experiment Video
Updated: Jul 8, 2026
Super-resolution Imaging of Proteus mirabilis Biofilm by Expansion Microscopy
Published on: July 18, 2025
Production and characterization of a bioflocculant by Proteus mirabilis TJ-1
Siqing Xia1, Zhiqiang Zhang, Xuejiang Wang
1State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Abstract:
A bioflocculant TJ-F1 with high flocculating activity, produced by strain TJ-1 from a mixed activated sludge, was investigated with regard to its production and characterization. By 16S rDNA sequence and biochemical and physiological characteristics, strain TJ-1 was identified as Proteus mirabilis. The most preferred carbon source, nitrogen source and C/N ratio (w/w) for strain TJ-1 to produce the bioflocculant were found to be glucose, peptone and 10, respectively. TJ-F1 production could be greatly stimulated by cations Ca(2+), Mg(2+) and Fe(3+). The optimal conditions for TJ-F1 production were inoculum size 2 per thousand (v/v), initial pH 7.0, culture temperature 25 degrees C, and shaking speed 130r/min, under which the flocculating activity of the bioflocculant reached 93.13%. About 1.33 g of the purified bioflocculant, whose molecular weight (MW) was 1.2 x 10(5) Da, could be recovered from 1.0 l of fermentation broth. Chemical analysis of bioflocculant TJ-F1 indicated that it contained protein (30.9%, w/w) and acid polysaccharide (63.1%, w/w), including neutral sugar, glucuronic acid and amino sugar as the principal constituents in the relative weight proportions of 8.2:5.3:1. Scanning electron microscopy (SEM) image of the purified solid-state TJ-F1 showed that it had a crystal-linear structure. Spectroscopic analysis of the bioflocculant by Fourier-transform infrared (FTIR) spectrometry indicated the presence of carboxyl, hydroxyl and amino groups preferred for the flocculation process.
Insights
Researchers identified Proteus mirabilis strain TJ-1 for producing bioflocculant TJ-F1. Optimal conditions and chemical composition were determined for high-yield bioflocculant production, showing potential for wastewater treatment applications.
Area of Science:
- Microbiology
- Biotechnology
- Environmental Science
Background:
- Bioflocculants offer a sustainable alternative to chemical flocculants in wastewater treatment.
- Identifying efficient microbial strains and optimizing production conditions are crucial for bioflocculant application.
Purpose of the Study:
- To investigate the production and characterization of a novel bioflocculant, TJ-F1, from a mixed activated sludge.
- To identify the microbial strain responsible for TJ-F1 production and determine optimal conditions for its maximal yield.
Main Methods:
- Strain identification using 16S rDNA sequencing, biochemical, and physiological tests.
- Optimization of carbon source, nitrogen source, C/N ratio, and cation supplementation.
- Determination of optimal fermentation conditions including inoculum size, pH, temperature, and shaking speed.
- Characterization of bioflocculant TJ-F1 including molecular weight, chemical composition, SEM, and FTIR analysis.
Main Results:
- Strain TJ-1 was identified as Proteus mirabilis.
- Optimal production involved glucose, peptone, a C/N ratio of 10, and stimulation by Ca(2+), Mg(2+), and Fe(3+).
- Optimal fermentation conditions yielded 93.13% flocculating activity, with 1.33 g purified bioflocculant recovered per liter.
- Bioflocculant TJ-F1 consists of protein (30.9%) and acid polysaccharide (63.1%), with a molecular weight of 1.2 x 10(5) Da.
Conclusions:
- Proteus mirabilis strain TJ-1 efficiently produces bioflocculant TJ-F1.
- The characterized bioflocculant possesses properties suitable for wastewater treatment applications.
- Optimized production conditions significantly enhance bioflocculant yield and activity.
