Fig. 1.
Fig. 2.
Fig. 3.
Degradation of lignin model compounds; guaiacol and veratryl alcohols by the bacterial isolates from the compost samples_
| S/N | Bacterial code | Isolation source | Guaiacol alcohol | Veratryl alcohol |
|---|---|---|---|---|
| 1 | Old A | Old cow dung | ++ | ++ |
| 2 | *Old A | Old cow dung | ++ | ++ |
| 3 | OOld A | Old cow dung | ++ | +++ |
| 4 | Old A1 | Old cow dung | + | + |
| 5 | *Old A2 | Old cow dung | + | ++ |
| 6 | Old A2 | Old cow dung | +++ | +++ |
| 7 | /*New A | Fresh cow dung | – | ++ |
| 8 | New A | Fresh cow dung | +++ | +++ |
| 9 | *New A | Fresh cow dung | – | ++ |
| 10 | New B | Fresh cow dung | ++ | ++ |
| 11 | ONew B | Fresh cow dung | – | – |
| 12 | *New B | Fresh cow dung | – | – |
| 13 | Saw A | Sawdust | – | – |
| 14 | Saw A1 | Sawdust | – | + |
| 15 | Saw A2 | Sawdust | +++ | +++ |
| 16 | Saw B | Sawdust | – | – |
| 17 | *Saw B | Sawdust | – | +++ |
| 18 | Saw B1 | Sawdust | – | ++ |
| 19 | Soil A | Soil | – | + |
| 20 | *Soil A | Soil | – | +++ |
| 21 | Soil A1 | Soil | + | ++ |
| 22 | *Soil B | Soil | + | +++ |
| 23 | Soil B | Soil | ++ | +++ |
| 24 | Soil B1 | Soil | +++ | +++ |
| 25 | Soil 2 | Soil | + | ++ |
| 26 | Soil 7 | Soil | + | ++ |
Quantitative analysis for the lignin peroxidase activity of the bacteria isolates_
| S/N | Bacterial strains | Lignin peroxidase activity (U/l) |
|---|---|---|
| 1 | Pseudomonas aeruginosa (MF144461.1) | 1.37 × 10–2a |
| 2 | Escherichia coli (LR025096.1) | 1.99 × 10–1b |
| 3 | Pseudomonas aeruginosa (KR136350.1) | 8.70 × 10–2c |
| 4 | Pseudomonas aeruginosa (CP031449.2) | 1.99 × 10–1b |
| 5 | Enterobacter xiangfangensis (MH304301.1) | 1.09 × 10–2d |
| 6 | Enterobacter kobei (CP032897.1) | 8.55 × 10–2c |
Identification of the isolated bacterial cultures by 16S rDNA_
| Bacterial name | Accession number (16S rRNA gene sequence) | Bacterial code |
|---|---|---|
| Pseudomonas aeruginosa | KR136350.1 | Soil B |
| Pseudomonas aeruginosa | KT799669.1 | *Old A |
| Pseudomonas aeruginosa | MF144461.1 | OOld A |
| Pseudomonas aeruginosa | KR136350.1 | New B |
| Pseudomonas aeruginosa | KR136350.1 | New A |
| Pseudomonas aeruginosa | CP031449.2 | Saw A2 |
| Pseudomonas aeruginosa | KT799669.1 | Soil B1 |
| Escherichia coli | LR025096.1 | Old A2 |
| Enterobacter kobei | CP032897.1 | Soil 7 |
| Enterobacter xiangfangensis | MH304301.1 | Soil 2 |
Lignin peroxidase and Laccase producing potential of the isolated bacteria_
| S/N | Bacterial code | Lignin peroxidase activity | Laccase activity |
|---|---|---|---|
| 1 | *Old A | +++ | – |
| 2 | OOld A | +++ | – |
| 3 | Old A2 | +++ | – |
| 4 | New A | +++ | – |
| 5 | New B | +++ | – |
| 6 | Saw A2 | +++ | – |
| 7 | Soil B | +++ | – |
| 8 | Soil B1 | +++ | – |
| 9 | Soil 2 | ++ | – |
| 10 | Soil 7 | ++ | – |
Decolourization of synthetic lignin-like dyes (halo zone measured in mm) by the selected ligninolytic bacterial isolates_
| S/N | Bacterial code | RBBR (mm) | AZ (mm) | CR (mm) |
|---|---|---|---|---|
| 1 | Old A | 15.0 ± 0.10c | 35.0 ± 0.04b | 0.00 ± 0.00f |
| 2 | *Old A | 26.0 ± 0.00b | 40.0 ± 0.01d | 42.0 ± 0.01a |
| 3 | OOld A | 24.0 ± 0.06b | 30.0 ± 0.00c | 31.0 ± 0.10c |
| 4 | Old A1 | 19.0 ± 0.00d | 29.0 ± 0.05c | 0.00 ± 0.00f |
| 5 | *Old A2 | 0.00 ± 0.00f | 34.0 ± 0.04e | 10.0 ± 0.20d |
| 6 | Old A2 | 35.0 ± 0.10a | 42.0 ± 0.11d | 40.0 ± 0.08a |
| 7 | New A | 8.00 ± 0.50e | 40.0 ± 0.00d | 20.0 ± 0.01e |
| 8 | New B | 30.0 ± 0.00h | 50.0 ± 0.01a | 26.0 ± 0.02b |
| 9 | Saw A2 | 15.0 ± 0.04c | 35.0 ± 0.02b | 12.0 ± 0.50d |
| 10 | Soil A1 | 0.00 ± 0.00f | 8.00 ± 0.01g | 24.0 ± 0.10b |
| 11 | *Soil B | 0.00 ± 0.00f | 25.0 ± 0.02f | 19.0 ± 0.00e |
| 12 | Soil B | 34.0 ± 0.00a | 50.0 ± 0.02a | 19.0 ± 0.10e |
| 13 | Soil B1 | 10.0 ± 0.06e | 37.0 ± 0.01b | 40.0 ± 0.03a |
| 14 | Soil 2 | 49.0 ± 0.00h | 25.0 ± 0.08f | 49.0 ± 0.01h |
| 15 | Soil 7 | 35.0 ± 0.02a | 16.0 ± 0.04h | 35.0 ± 0.05i |
Characteristics of ligninolytic bacteria from cow dung, sawdust, and soil samples_
| Bacterial code | Catalase test | Oxidase test | Starch hydrolysis | Urease test | Indole test | Citrate test |
|---|---|---|---|---|---|---|
| *Old A | + | – | + | – | + | – |
| OOld A | + | + | + | – | + | – |
| Old A2 | + | + | + | – | + | – |
| New A | + | + | + | – | + | – |
| New B | + | + | + | – | + | – |
| Saw A2 | + | – | + | – | + | – |
| Soil B | + | – | + | – | + | – |
| Soil B1 | + | – | + | – | + | – |
| Soil 2 | + | + | + | – | + | – |
| Soil 7 | + | – | + | – | + | – |