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Ammi visnaga (L.) Lam is a valuable herbal plant that is frequently collected for medicinal purposes. This study is conducted to evaluate the antimicrobial potential of the in-vitro grown microshoots and callus cultures of this plant against selected strains of bacteria and fungi. Shoot multiplication was obtained in MS medium containing 0.5 mg/L BA + 0.1 mg/L NAA, while callus multiplication was performed on MS medium containing 1.0 mg/L BA + 2.0 mg/L 2,4-D under light conditions. The aqueous and methanolic extracts were prepared from both culture types in addition to in-vivo grown plant material to experiment their antimicrobial activities. Generally, the in-vitro extracts of the microshoots and the callus cultures acted best against bacteria compared to the field plant extract. Moreover, the methanolic extracts were generally found to exhibit far better results and resistance against the tested microbes than the aqueous extracts. C. albicans was the most sensitive species to the microshoots extracts followed by gram-positive bacteria at MIC values of (3.125, 6.25) mg/mL. Meanwhile, E. coli bacteria were most sensitive to the microshoot extracts as they were completely inhibited at MIC value of (0.78 mg/mL). Moreover, the results of the callus extracts showed that C. albicans was the most sensitive at MIC values of (1.56 and 3.125) mg/mL, followed by gram-positive bacteria. On the other hand, gram-negative bacteria were the most resistant microbes to all experimented extract types in this study. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]