Exploration of an extracellular polymeric substance from earthworm gut bacterium (Bacillus licheniformis) for bioflocculation and heavy metal removal potential

Jayanta Kumar Biswas, Anurupa Banerjee, Binoy Sarkar, Dibyendu Sarkar, Santosh Kumar Sarkar, Mahendra Rai, Meththika Vithanage

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

The present study shows the potential of an extracellular polymeric substance (EPS) produced by Bacillus licheniformis strain KX657843 isolated from earthworm (Metaphire posthuma) gut in the sorption of Cu(II) and Zn(II)and inflocculation. After harvesting bacterial cells from sucrose supplemented denitrifying culture medium, the EPS was extracted following ethanolic extraction method. The Fourier Transform Infrared Spectroscopy (FTIR) and 1H and 13C Nuclear Magnetic Resonance (NMR) of EPS revealed its functional groups, electronegative constituents, unsaturated carbon, and carbonyl groups. The negatively charged functional groups of carbohydrates and protein moiety of the EPS endowed it with heavy metal binding capacity through electrostatic interactions. The highest flocculation activity (83%) of EPS was observedat 4 mg L-1 and pH 11. The metal sorption by EPS increased with increasing pH. AtpH 8, the EPS was able to remove 86 and 81% Cu(II) and Zn(II), respectively, from a 25 mg L-1 metal solution.94.8% of both the metals at 25 mg L-1 metal solutions were removed by EPS at EPS concentration of 100 mg L-1. From Langmuir isotherm model, the maximum sorption capacities of EPS were calculated to be 58.82 mg g-1 for Cu(II) and 52.45 mg g-1 for Zn(II). The bacterial EPS showed encouraging flocculating and metal sorption properties. The potential to remove Cu(II) and Zn(II) implies that the EPS obtained from the earthworm gut bacteria can be used as an effective agent for environmental remediation of heavy metals and in bioflocculation.

Original languageEnglish
Article number349
JournalApplied Sciences (Switzerland)
Volume10
Issue number1
DOIs
StatePublished - 1 Jan 2020

Keywords

  • Earthworm
  • Extracellular polymeric substances
  • Flocculation
  • Gut bacteria
  • Isotherm models
  • Metal remediation

Fingerprint

Dive into the research topics of 'Exploration of an extracellular polymeric substance from earthworm gut bacterium (Bacillus licheniformis) for bioflocculation and heavy metal removal potential'. Together they form a unique fingerprint.

Cite this