Table I
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 | + | ++ |
Table II
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 |
Table III
Lignin peroxidase and Laccase producing potential of the isolated bacteria.
Table IV
Characteristics of ligninolytic bacteria from cow dung, sawdust, and soil samples.
Table V
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 |
Fig. 1.
Graphs of lignin degradation capability, pH variation, and growth of E. coli, P. aeruginosa, E. kobei, and E. xiangfangensis.
Fig. 2.
Enzyme activity (the recovered supernatant) of E. coli (LR0250096), and P. aeruginosa (CP031449.2) on the lignin enriched medium.
Table VI
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 |
Fig. 3.
The phylogenetic tree of the bacteria from this study (red) in relation to some other ligninolytic bacteria in the NCBI database.