Fig. 1a.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Corrosion rates and inhibition efficiencies for mild steel corrosion in seawater in the presence of BAC1 (Pseudoalteromonas phenolica) over a 24-week immersion period_
| Immersion period (weeks) | Weight loss Δw (g) | Pit depth Pd (μm) | Corrosion rate CRWL (μm y−1) | IEWL% |
|---|---|---|---|---|
| 1st | 0.0008 ± 0.00003 | 0.05 ± 0.01 | 2.64 ± 0.10 | 92.78 ± 1.1 |
| 2nd | 0.0016 ± 0.00005 | 0.12 ± 0.02 | 3.04 ± 0.12 | 89.65 ± 1.2 |
| 4th | 0.0021 ± 0.00007 | 0.15 ± 0.02 | 1.95 ± 0.08 | 93.41 ± 1.0 |
| 6th | 0.0023 ± 0.00008 | 0.17 ± 0.02 | 1.44 ± 0.07 | 95.08 ± 0.9 |
| 9th | 0.0029 ± 0.00009 | 0.21 ± 0.03 | 1.19 ± 0.05 | 96.37 ± 0.8 |
| 12th | 0.0028 ± 0.00008 | 0.20 ± 0.03 | 0.86 ± 0.04 | 92.76 ± 0.7 |
| 16th | 0.0150 ± 0.0004 | 1.06 ± 0.05 | 3.45 ± 0.14 | 59.74 ± 1.5 |
| 24th | 0.0255 ± 0.0006 | 1.66 ± 0.06 | 3.60 ± 0.15 | 70.94 ± 1.4 |
Corrosion rates and inhibition efficiencies for mild steel corrosion in seawater in the presence of BAC 2 (Pseudoalteromonas shioyasakiensis) over a 24-week immersion_
| Immersion period (weeks) | Weight loss Δw (g) | Pit depth Pd (μm) | Corrosion rate CRWL (μm y−1) | IEWL% |
|---|---|---|---|---|
| 1st | 0.0003 ± 0.00001 | 0.02 ± 0.01 | 1.11 ± 0.05 | 96.96 ± 0.9 |
| 2nd | 0.0010 ± 0.00004 | 0.09 ± 0.02 | 2.43 ± 0.10 | 91.72 ± 1.1 |
| 4th | 0.0024 ± 0.00006 | 0.17 ± 0.02 | 2.26 ± 0.09 | 92.37 ± 1.0 |
| 6th | 0.0025 ± 0.00007 | 0.19 ± 0.02 | 1.67 ± 0.08 | 94.28 ± 0.9 |
| 9th | 0.0027 ± 0.00008 | 0.19 ± 0.02 | 1.12 ± 0.05 | 96.60 ± 0.8 |
| 12th | 0.0022 ± 0.00007 | 0.16 ± 0.02 | 0.69 ± 0.03 | 94.18 ± 0.7 |
| 16th | 0.0156 ± 0.0005 | 1.10 ± 0.05 | 3.57 ± 0.13 | 58.27 ± 1.6 |
| 24th | 0.0228 ± 0.0006 | 1.62 ± 0.06 | 3.52 ± 0.14 | 71.55 ± 1.4 |
Impedance parameters for corrosion of mild steel in sweater in the absence and presence of bacterial inhibitors_
| Medium | Time (h) | Rs(Ω cm2) | Rct (Ω cm2) | Cdl (μF cm-2) | IER% |
|---|---|---|---|---|---|
| Blank | 1 | 3.73 ± 0.08 | 916.7 ± 35 | 15.68 ± 0.6 | – |
| BAC 1 | 5.31 ± 0.12 | 8826.0 ± 110 | 4.48 ± 0.2 | 89.61 ± 1.2 | |
| BAC 2 | 5.67 ± 0.13 | 6914.0 ± 95 | 4.923 ± 0.2 | 86.74 ± 1.1 | |
| BAC 3 | 3.19 ± 0.09 | 6128.0 ± 90 | 5.18 ± 0.2 | 85.05 ± 1.0 | |
| Blank | 24 | 4.51 ± 0.10 | 631.6 ± 30 | 20.01 ± 0.7 | – |
| BAC 1 | 4.87 ± 0.11 | 1183.0 ± 45 | 9.61 ± 0.3 | 46.61 ± 1.1 | |
| BAC 2 | 5.09 ± 0.12 | 8112.0 ± 102 | 2.07 ± 0.1 | 92.22 ± 1.3 | |
| BAC 3 | 3.45 ± 0.10 | 1118.0 ± 42 | 10.25 ± 0.4 | 43.56 ± 1.0 |
Polarization parameters for corrosion of mild steel in sweater in the absence and presence of bacterial inhibitors_
| Medium | Time (h) | –Ecorr(mv) | βa (mV dec-1) | -βc (mV dec-1) | icorr (mA cm-2) | IEi % |
|---|---|---|---|---|---|---|
| Blank | 1 | 538.4 ± 2.1 | 80.25 ± 1.5 | 43.73 ± 1.2 | 0.3607 ± 0.012 | – |
| BAC 1 | 478.7 ± 1.8 | 70.28 ± 1.2 | 121.92 ± 1.6 | 0.0099 ± 0.0004 | 97.25 ± 0.8 | |
| BAC 2 | 449.1 ±1.7 | 84.28 ± 1.4 | 155.09 ± 1.7 | 0.0097 ± 0.0003 | 97.31 ± 0.9 | |
| BAC 3 | 429.2 ± 1.6 | 92.80 ± 1.4 | 97.73 ± 1.4 | 0.0081 ± 0.0003 | 97.75 ± 0.9 | |
| Blank | 24 | 524.1 ± 2.0 | 54.64 ± 1.3 | 57.39 ± 1.3 | 0.4991 ± 0.015 | – |
| BAC 1 | 405.0 ± 1.9 | 62.54 ± 1.1 | 123.19 ± 1.5 | 0.0229 ± 0.0006 | 95.41 ± 0.7 | |
| BAC 2 | 449.5 ± 1.8 | 97.49 ± 1.6 | 150.68 ± 1.6 | 0.0189 ± 0.0005 | 96.21 ± 0.8 | |
| BAC 3 | 566.3 ± 2.2 | 94.02 ± 1.5 | 80.17 ± 1.3 | 0.1868 ± 0.006 | 62.57 ± 1.2 |
Corrosion rates and inhibition efficiencies for mild steel corrosion in seawater in the presence of BAC 3 (Alteromonas mediterranea) over a 24-week immersion period_
| Immersion period (weeks) | Weight loss Δw (g) | Pit depth Pd (μm) | Corrosion rate CRWL (μm y−1) | IEWL% |
|---|---|---|---|---|
| 1st | 0.0001 ± 0.00001 | 0.007 ± 0.01 | 0.36 ± 0.02 | 99.00 ± 0.5 |
| 2nd | 0.0009 ± 0.00003 | 0.07 ± 0.02 | 1.74 ± 0.08 | 94.06 ± 0.9 |
| 4th | 0.0017 ± 0.00006 | 0.12 ± 0.02 | 1.60 ± 0.07 | 94.59 ± 0.8 |
| 6th | 0.0027 ± 0.00007 | 0.18 ± 0.03 | 1.56 ± 0.07 | 94.65 ± 0.8 |
| 9th | 0.0036 ± 0.00008 | 0.26 ± 0. 03 | 1.52 ± 0.06 | 95.39 ± 0.7 |
| 12th | 0.0038 ± 0.00009 | 0.27 ±0.04 | 1.18 ± 0.05 | 90.11 ± 0.6 |
| 16th | 0.0159 ± 0.0005 | 1.16 ± 0.05 | 3.80 ± 0.15 | 55.65 ± 1.8 |
| 24th | 0.0786 ± 0.0012 | 5.44 ± 0.10 | 11.82 ± 0.30 | 4.57 ± 2.0 |
Information and identification for 16S rRNA gene sequences of BAC1, BAC 2, and BAC 3_
| Code | Reference accession numbers | Identified bacterial isolates | Identity % |
|---|---|---|---|
| BAC 1 (OR852740.1) | NR 113299.1 | Pseudoalteromonas phenolica | 99.42% |
| NR 028809.1 | Pseudoalteromonas phenolica | 98.27% | |
| KY073271 | Pseudoalteromonas phenolica | 99.80% | |
| BAC 2 (OR852741.1) | NR 125458.1 | Pseudoalteromonas shioyasakiensis | 96.67% |
| BAC 3 (OR852743.1) | NR 148755.1 | Alteromonas mediterranea | 98.17% |
| NR 148756.1 | Alteromonas mediterranea | 98.46% |
Pit depth and corrosion rates of mild steel control at different immersion time in seawater_
| Immersion period (weeks) | Weight loss Δw (g) | Pit depth Pd (μm) | Corrosion rate CRWL (μm y−1) |
|---|---|---|---|
| 1st | 0.0097 ± 0.0006 | 0.70 ± 0.03 | 36.54 ± 1.12 |
| 2nd | 0.0161 ± 0.0011 | 1.13 ± 0.05 | 29.37 ± 0.94 |
| 4th | 0.0311 ± 0.0018 | 2.27 ± 0.07 | 29.55 ± 0.97 |
| 6th | 0.0484 ± 0.0024 | 3.36 ± 0.09 | 29.19 ± 1.03 |
| 9th | 0.0820 ± 0.0031 | 5.68 ± 0.12 | 32.93 ± 1.22 |
| 12th | 0.0398 ± 0.0042 | 2.75 ± 0.10 | 11.95 ± 0.81 |
| 16th | 0.0368 ± 0.0054 | 2.63 ± 0.09 | 8.56 ± 0.63 |
| 24th | 0.0789 ± 0.0079 | 5.70 ± 0.14 | 12.38 ± 0.77 |
Chemical analysis of Red Sea water sample_
| Parameter | Value | Unit |
|---|---|---|
| Salt-related ions | ||
| Ca2+ | 496.0 | mg/l |
| Mg2+ | 1,512.0 | |
| Na+ | 11,920.0 | |
| K+ | 588.0 | |
| Cl– | 22,336.0 | |
| HCO3– | 156.0 | |
| NO3– | 1.0 | |
| SO43– | 2,440.0 | |
| PO3– | < 0.1 | |
| CO32– | < 0.1 | |
| SiO2 | < 1.0 | |
| Other Parameters | ||
| Total dissolved solid (TDS) | 43,550.0 | mg/l |
| Total suspended solids (TSS) | < 5.0 | mg/l |
| Total alkalinity | 128.0 | mg/l as CaCO3 |
| pH | 8.1 | |
| Conductivity | 72,550.0 | μS/cm2 |