Nanochemistry and biotechnology

Green Synthesis of Silver Nanoparticles Using Penicillium citrinum, and Their Antibiotic Activity
A.Yu. Chobotarov, K.S. Tsyganenko, Ya.I. Savchuk, L.T. Nakonechna
Department of Physiology and Taxonomy of Micromycetes, Zabolotny Institute of Microbiology and Virology of the NAS of Ukraine. Akad. Zabolotny Str., 154, Kyiv-03143, Ukraine.
E-mail: andreych@ukr.net

Penicillium citrinum strain 125 was grown in modified Czapek-Dox medium at 26 °C on a rotary shaker at 160 rpm for seven days. The biomass was harvested by filtration through Whatman filter paper N 1, and washed with distilled water to remove any residual medium components. 8-10 g wet biomass were placed in individual shake flasks containing 100 mL working volume of double distilled water. The flasks were cultivated under the same conditions for 48 h. The culture was centrifuged at 6 600 g for 20 min, and the supernatant was used to subsequent AgNPs synthesis. AgNPs were synthesized using 50 mL cell-free filtrate mixed with 10 mL AgNO3 solution (final concentration was 1 mmol/L) in a shake flask incubated at 26 °C in dark for 48 h. A flask with no addition of silver solution was used as a control. The colours of the solutions changed from yellow to dark buff, indicating the formation of AgNPs in the sol. The UV-Vis spectrum of the AgNPs solutions were recorded in 420 nm, the morphology and particle sizes detected by TEM were in the range of 12-35 nm. The main aim of present work was the determination of the minimum inhibitory concentration (MIC) and of minimum bactericidal or fungicidal concentration (MBC/MFC) of sol obtained by green synthesis on a set of pharmacopoeia test cultures.
Table. The MIC and MBC/MFC values of the AgNPs
sol obtained by green synthesis using P. citrinum 125
Test cultures	Dilutions	
	MIC	MBC/MFC	
Escherichia coli АТСС 25922	1:128	1:64	
Staphylococcus aureus ATCC 6538	1:16	1:8	
Bacillus subtilis ATCC 6633	1:32	1:16	
Candida albicans ATCC 10231	1:32	1:16	
These values were defined by two-fold broth dilution methods in a liquid nutrient medium dispensed in tubes containing a 2 mL volume. Each tube was inoculated with a test inoculum with 0.5 McFarland scale. The findings showed (table) the prospect of further investigations of antibiotic activity of AgNPs in the direction of the fight against antibiotic-resistant human pathogens.