Osmotic Stress Enhances Antimicrobial Activity of in Vitro Grown Microshoots of Ochradenus Baccatus Delile Against Selected microbes

Ochradenus baccatus Delile is a wild medicinal plant that produces several natural compounds with medicinal benefits. In this study, microshoots of Ochradenus baccatus were exposed to osmotic stress conditions consisting of Murashige and Skoog solid media (MS) media that containing different osmotic agents (sugar types) at a range of concentrations (including 0.1, 0.2, 0.3 or 0.4 M). The purpose was to test their effects on microshoots’ growth and antimicrobial activities against selected strains of bacteria and one strain of fungi. It has been found that growth parameters (including shoot length and proliferation) of Ochradenus baccatus microshoots declined with increasing sugar concentration in the media, but at the highest concentrations of 0.4M mannitol, the micorshoots could not survive. Generally, aqueous extracts of the stressed microshoots were more effective against the tested microbial strains than the methanolic extracts in most experiments. Staphylococcus aureus was found to be the most affected microbe to both extract types. Also, exposing the microshoots to osmotic stress had improved antimicrobial powers in both extracts types. Aqueous extract of microshoots that pre-grew in media with (0.4 M sucrose) was interestingly found to inhibit growth of Staphylococcus aureus and Candida albicans with minimal inhibitory concentration (MIC) values of (0.195, 0.78 mg/ml). These values were similar to those obtained from the antibiotic treatments. Other biotechnological techniques like genetic transformation are suggested to be also used for production of elite strains of Ochradenus baccatus with super antimicrobial potential.