Antioxidant, antibacterial, and anti-adhesive activities of biosurfactants isolated from Bacillus strains.

Biosurfactants are surface-active compounds that display a range of physiological functions. The present study investigated the antioxidant, antimicrobial, and anti-adhesive or anti-biofilm potential of biosurfactants isolated from Bacillus subtilis VSG4 and Bacillus licheniformis VS16. The antioxidant activity of the biosurfactants was studied in vitro using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. At 5 mg/mL of the biosurfactant concentration, the scavenging of DPPH and hydroxyl radicals was found to be between 69.1-73.5% and 63.3-69.8%, respectively. The biosurfactants also displayed significant antibacterial activities against both Gram-positive and Gram-negative bacteria. The anti-adhesive activities of the biosurfactants were evaluated against Staphylococcus aureus ATCC 29523, Salmonella typhimurium ATCC 19430, and Bacillus cereus ATCC 11778. The biosurfactants exhibited anti-adhesive activity, even at concentrations of 3-5 mg/mL. Moreover, both biosurfactants displayed notable anti-biofilm activities with a biofilm eradication percentage ranging from 63.9 to 80.03% for VSG4 biosurfactant, and from 61.1-68.4% for VS16 biosurfactant. Furthermore, VSG4 biosurfactant exhibited emulsification and surface tension stability over a wide range of pH (4-10) and temperature up to 100 °C. These results show that VSG4 and VS16 biosurfactants can be potentially used as natural antioxidants, antimicrobials, and/or anti-adhesive agents for food and biomedical applications.

Giri SS ，Ryu EC ，Sukumaran V ，Park SC ... -  《-》

Antioxidant and antiproliferative potential of biosurfactants isolated from Lactobacillus casei and their anti-biofilm effect in oral Staphylococcus aureus strains.

Biosurfactants also called bioemulsifiers are amphipathic compounds produced by many microorganisms that allow them to exhibit a wide range of biological activities. The aim of this study was to determine the antioxidant and antiproliferative potential of biosurfactants isolated from Lactobacillus casei and to assess their anti-adhesive and anti-biofilm abilities against oral opportunistic Staphylococcus aureus strains. The antioxidant activity of biosurfactant was evaluated using the in vitro scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The antiproliferative activity was determined on epithelial cell line (HEp-2) by the Methylthiazole tetrazolium (MTT) reduction assay. The anti-adhesive and antibiofilm activity against S. aureus strains were achieved using crystal violet staining. Our results revealed that the DPPH scavenging activity of biosurfactants at 5.0 mg/mL concentration is between 74.6 and 77.3%. Furthermore, biosurfactants showed antiproliferative potency against studied epithelial cells as judged by IC50 and its value ranged from 109.1 ± 0.84 mg/mL to 129.7 ± 0.52 mg/mL. The results of the growth inhibition indicate that biosurfactant BS-LBl was more effective against oral S. aureus strains 9P and 29P with an IC50 of 1.92 ± 0.26 mg/mL and 2.16 ± 0.12 mg/mL respectively. Moreover, both biosurfactants displayed important antibiofilm activity with eradication percentages ranging from 80.22 ± 1.33% to 86.21 ± 2.94% for the BS-LBl, and from 53.38 ± 1.77% to 64.42 ± 2.09% for the BS-LZ9. Our findings demonstrate that biosurfactants from L. casei strains exhibited considerable antioxidant and antiproliferative potencies and were able to inhibit oral S. aureus strains with important antibiofilm efficacy. They could have a promising role in the prevention of oral diseases.

Merghni A ，Dallel I ，Noumi E ，Kadmi Y ，Hentati H ，Tobji S ，Ben Amor A ，Mastouri M ... -  《-》

Antioxidant properties, antimicrobial and anti-adhesive activities of DCS1 lipopeptides from Bacillus methylotrophicus DCS1.

Jemil N ，Ben Ayed H ，Manresa A ，Nasri M ，Hmidet N ... -  《-》

Anti-adhesion activity of two biosurfactants produced by Bacillus spp. prevents biofilm formation of human bacterial pathogens.

Rivardo F ，Turner RJ ，Allegrone G ，Ceri H ，Martinotti MG ... -  《-》

Biofilm inhibition and antimicrobial action of lipopeptide biosurfactant produced by heavy metal tolerant strain Bacillus cereus NK1.

Biosurfactants are worthful microbial amphiphilic molecules with efficient surface-active and biological properties applicable to several industries and processes. Among them lipopeptides represent a class of microbial surfactants with increasing scientific, therapeutic and biotechnological interests. A heavy metal tolerant Bacillus strain has been isolated and the biofilm inhibition and antimicrobial activity of biosurfactant produced by the strain have been studied. Biosurfactant production was confirmed by the conventional screening methods including hemolytic activity, drop collapsing test, oil displacement test, emulsification and lipase production assays. The biosurfactant produced by this strain was a lipopeptide and exhibited strong surface activity. The biosurfactant has been characterized using FTIR, TLC and HPLC. The minimum active dose of this biosurfactant when compared with the other chemical surfactants was found as 0.150±0.06 μg. The critical micelle concentration was found to be 45 mg/l. The biosurfactant was found to be stable and active over a wide range of pH, temperature and NaCl concentration. It was also able to emulsify a wide range of hydrocarbons and oils thereby extending its application for the bioremediation of oil contaminated sites. The biosurfactant exhibited significant reduction in biofilm formation by pathogens and showed potent antimicrobial activity against various gram positive, gram negative bacteria and fungi. Agar diffusion assay for heavy metal resistance showed that the isolate was resistant to ferrous, lead and zinc. Considering the biofilm inhibition and antimicrobial property of biosurfactant, it can be utilized as a potential therapeutic molecule for numerous microbial infections. The heavy metal resistance of the strain can also be harnessed as an invaluable biological tool for in situ bioremediation.

Sriram MI ，Kalishwaralal K ，Deepak V ，Gracerosepat R ，Srisakthi K ，Gurunathan S ... -  《-》