Table 1
Microalgal strains isolated from Tunisian inland water bodies (river, lagoon, dam reservoir, spring) with location and culture mediums
| Strain | Class/Order | Sampling site | Culture medium | |
|---|---|---|---|---|
| Dunaliella sp. | Duna-GV | Chlorophyceae/Chlamydomonadales | El Grine Sabkha 33°38′55″N; 10°32′33″E S: 56 PSU | CONWAY |
| Chroococcus sp. | Chroo-CH | Cyanobacteria / Chroococcales | Chanchou River 33°54′3″N; 9°43′22″E S: 4.2 PSU | BG11 |
| Arthrospira platensis | Arthro-KB | Cyanobacteria / Oscillatoriales | Korba lagoon 36°36′43″N; 10°53′13″E S: 16 PSU | BG11 |
| Leptolyngbya sp1. | Osci-NB-01 | Nabhena reservoir 36°03′57″N; 9°51′54″E S: 0.5 PSU | BG11 | |
| Leptolyngbya sp2. | Lepto-CH | Chanchou River 33°54′3″N; 9°43′22″E S: 4.2 PSU | BG11 | |
| Limnotrix sp. | Osci-BM-01 | Bir Mcherga reservoir 36°30′32″N; 10°00′36″E S: 1.6 PSU | BG11 | |
| Planktothrix agardhii | Plank-SS-01 | Sidi Saad reservoir 35°22′51″N; 9°41′20″E S: 1.9 PSU | BG11 | |
| Spirulina sp. | Spir-ML | Maltine River 34°24′56″N; 10°19′45″E S: 45 PSU | CONWAY | |
| Anabaenopsis circularis | Pseud-01 | Cyanobacteria / Nostocales | Siliana spring 35°54′39″N; 9°20′06″E S: 0.2 PSU | BG11 |
| Cylindrospermopsis raciborskii | Cyl-NB-05 | Nabhena reservoir 36°03′57″N; 9°51′54″E S: 0.5 PSU | BG11 | |
[i] S – salinity; PSU – practical salinity unit
Table 2
Molecular identification of microalgal strains isolated from different Tunisian inland water bodies with % of similarity according to the BLAST database and accession numbers
| Strain | Taxon according to BLAST database | % of similarity | Accession numbers | |
|---|---|---|---|---|
| 16S rRNA | rpoC1 | |||
| Osci-NB-01 | Leptolyngbya sp. | 99 | MG762090 | - |
| Osci-BM-01 | Limnotrix sp. | 100 | MG762091 | - |
| Plank-SS-01 | Planktothrix agardhii | 100 | MG762092 | - |
| Cyl-NB-05 | Cylindrospermopsis raciborskii | 96 | - | HQ389355 |
| Pseud-01 | Anabaenopsis circularis | 99 | MG098078 | - |
| Arthro-KB | Arthrospira platensis | 100 | MG098079 | - |
| Lepto-CH | Leptolyngbya sp. | 99 | MG098077 | - |
| Spir-ML | Spirulina sp. | 99 | MG518486 | - |
Figure 1
Phycobiliprotein concentration of cyanobacterial strains isolated from different aquatic habitats expressed in μg per ml of fresh culture. Bars indicate the standard deviation of three replicates (PC = Phycocyanin; APC = Allophycocyanin; PE = Phycoerythrin)
Table 3
Phenolics, flavonoids and antioxidant activity of microalgal extracts
| Strain | Code | TPP (mg EqGA/g DW) | TF (mg EqC/g DW) | Antioxidant activity against DPPH (IC50, μg ml−1) |
|---|---|---|---|---|
| Chroococcus sp. | Chroo-CH | 8.90 ± 0.25 | 67.94 ± 1.36 | 212.15 ± 2.07 |
| Leptolyngbya sp1. | Osci-NB-01 | 1.81 ± 0.39 | 58.46 ± 0.73 | 263.91 ± 14.93 |
| Arthrospira platensis | Arthro-KB | 2.85 ± 0.06 | 74.09 ± 5.28 | 953.94 ± 28.14 |
| Leptolyngbya sp2. | Lepto-CH | 7.75 ± 0.77 | 68.17 ± 3.96 | 782.87 ± 4.2 |
| Planktothrix agardhii | Plank-SS-01 | 4.86 ± 0.3 | 38.32 ± 5.37 | NA |
| Anabaenopsis circularis | Pseud-01 | 5.63 ± 0.15 | 38.05 ± 4.43 | 912.21 ± 2.21 |
| Cylindrospermopsis raciborskii | Cyl-NB-05 | ND | 1.48 ± 0.03 | NA |
| Limnotrix sp. | Osci-BM-01 | 1.77 ± 0.13 | 36.31 ± 3.12 | NA |
| Spirulina sp. | Spir-ML | ND | 5.03 ± 1 | NA |
| Dunaliella sp. | Duna-GV | 3.07 ± 0.32 | 37.94 ± 3.11 | 681 ± 20,07 |
| BHT | - | - | - | 17.34 ± 0.23 |
[i] TPP – total polyphenols; TF – total flavonoids; DW – dry weight; GA – gallic acid ; C – catechin ; BHT – butylated hydroxytoluene ; NA – not active at maximum concentration; ND – not detectable. Results represent means of three replicates with standard deviation (Means ± SD, n = 3)
Table 4
Antibacterial activity of microalgal extracts
| Strain | Inhibition zone diameter (mm) [MIC (μg ml−1)] | |||||
|---|---|---|---|---|---|---|
| B. cereus ATCC 14579 | E. faecalis ATCC 29212 | S. aureus ATCC 25923 | MRSA | E. coli ATCC 35218 | P. aeruginosa ATCC 27853 | |
| Chroo-CH | NA | NA | NA | NA | NA | NA |
| Osci-NB-01 | NA | NA | NA | NA | NA | NA |
| Arthro-KB | NA | NA | NA | NA | NA | NA |
| Lepto-CH | NA | NA | NA | NA | NA | NA |
| Plank-SS-01 | NA | NA | NA | NA | NA | NA |
| Pseud-01 | NA | NA | NA | NA | NA | NA |
| Cyl-NB-05 | NA | NA | NA | NA | NA | NA |
| Osci-BM-01 | NA | NA | NA | NA | NA | NA |
| Spir-ML | NA | NA | NA | NA | NA | NA |
| Duna-GV | NA | NA | NA | 16 ± 0.1 [375] | NA | NA |
[i] NA – not active at maximum concentration
Table 5
Antileishmanial activity of microalgal extracts
| Strain | IC50 ± SD (μg ml−1) | |
|---|---|---|
| L. infantum (LVMon) | L. major (gLC94) | |
| Chroo-CH | 713.4 ± 0.24 | 1000 ± 1.96 |
| Osci-NB-01 | 448.7 ± 0.24 | 728.5 ± 1.21 |
| Arthro-KB | > 1000 | > 1000 |
| Lepto-CH | 212.7 ± 1.46 | 401.9 ± 1.22 |
| Plank-SS-01 | 1000 ± 1.98 | > 1000 |
| Pseud-01 | 1000 ± 2.38 | > 1000 |
| Cyl-NB-05 | 246.4 ± 1.66 | 473.8 ± 0.53 |
| Osci-BM-01 | 188.7 ± 1.35 | 377.5 ± 0.09 |
| Spir-ML | 1000 ± 2.44 | > 1000 |
| Duna-GV | 151.2 ± 0.37 | 284.87 ± 1.46 |
| Amphotericin B | 0.64 ± 0.24 | 0.97 ± 0.08 |
[i] IC50 = Inhibitory Concentration 50 (μg ml−1); Amphotericin B = positive control.
[ii] SD – standard deviation; each value was represented as mean ± SD (n = 3)