Part:BBa_K4767002

ptpA

This part encodes a tyrosine phosphatase involved in the biosynthesis of extracellular polysaccharide in Shewanella oneidensis MR-1. Unconductive polysaccharide in S. oneidensis MR-1biofilm matrix attenuate the efficiency of extracellular electron transfer. We knocked out ptpA from S. oneidensis MR-1 genome to enhance its ability to generate electricity.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Functional Parameters

We created the ptpA knockout mutant and complementation strain to verify its function in the formation and conductivity of S. oneidensis MR-1 biofilm. The growth curves of wild-type(WT), ∆ptpA and the complementation strain showed that the ptpA deletion does not affect cell growth (Figure 1A). Our results show that the ability of the mutant strain to form biofilm on both conductive (well plate) and non-conductive (anode) surfaces significantly reduced, whereas the complementation strain restored this capability (Figure 1B and D). In microbial fuel cells (MFCs), maximum voltage of the mutant strain with the lower internal resistance raised about 36% compared to the wild type (Figure 1C and E). In summary, we come to the conclusion that ptpA gene in S. oneidensis MR-1 may possibly effect the biofilm formation and its conductivity by meditating the polysaccharide biosynthesis.

Figure 1. (A) The growth curves of the wild-type(WT), ∆ptpA and the complementation strain. The biofilm formed by three strains on the surfaces of non-conductive 24-well plates (B) and MFC anodes (D). The ability for the mutant strain to form biofilm is reduced compared to the WT and complementation on both surfaces. The electricity generation (C) and internal resistance (E) of WT, ∆ptpA and the complementation strain.

Moreover, with the thinner biofilm and lower resistance of the MFC, we can use this engineered strain to detect environmental pollution. In our experiment, we noticed that the mutant strain is more sensitive to arsenic than WT in the MFC, increasing the detection range of arsenic (Figure 2).

Figure 2. The decreased voltages of MFCs with WT and ∆ptpA biofilms under exposure to As(Ⅲ) with the concentrations of (A) 100, (B) 50, (C) 25 mg/L.

References

Hu Y, Wang Y, Han X, et al. Biofilm biology and engineering of Geobacter and Shewanella spp. for energy applications[J]. Frontiers in Bioengineering and Biotechnology, 2021,9:1252-1265.

Kouzuma A, Meng X, Kimura N, et al. Disruption of the putative cell surface polysaccharide biosynthesis gene SO3177 in Shewanella oneidensis MR-1 enhances adhesion to electrodes and current generation in microbial fuel cells[J]. Applied and Environmental Microbiology, 2010,76(13):4151-4157.

biology	Shewanella Oneidensis
protein	PtpA