Antimicrobial Activity and Chemical Composition of Pistachia Atlantica Gum Sub Sp. Kurdica. Essential Oil
 
Hasan Ellahi; MSc¹, Elham Khalili Sadrabad; PhD¹, Seyed Hossein Hekmatimoghaddam; MD², Ali Jebali; PhD³, Jalal Sadeghizadeh-yazdi⁴; PhD, Fatemeh Rastiani; MSc¹ & Fateme Akrami Mohajeri; PhD^*1
 
1Zoonotic Diseases Research Center, Department of Food Hygiene and Safety, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
²Department of Advanced Medical Sciences and Technologies, School of Paramedicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
³Department of Laboratory Sciences, School of Paramedicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
⁴Departmeny of Food Sciences and Technology, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
 

 
Introduction

Food can be contaminated by pathogenic bacteria including Salmonella enterica, Staphylococcus aureus, Escherichia Coli (E. Coli), and Listeria monocytogenes, which can cause several problems in gastro intestinal tract. During the last decades, extensive use of antimicrobial drugs has led to bacterial resistance in human beings (Moshafi et al., 2004). Essential oils (EO) are aromatic oils extracted from plants by different methods (Burt, 2004). Essential oils have been recognized as natural and harmless antimicrobial agents for the environment and Generally Recognized As Safe (GRAS) in food application (Nawel et al., 2013). The antibacterial effects of EOs depend on the type of plant, meteorological conditions, place of growth, as well as drying and processing methods. The use of oil plants in Iran as an antioxidant or antibiotic was traced back to ancient times (Akrami et al., 2015). Pistachio atlantica subsp. Kurdica, called Baneh, is one of the wild pistachio species (grows in Zagros forests), which belongs to the Anacardiacea family (Karimi et al., 2009). Three subspecies of cabulica, kurdica, and mutica grow in Iran. Over 1,200,000 hectares of western, central, and eastern parts of Iran are covered by kurdica and mutica subspecies (Farhoosh et al., 2008). Pistacia atlantica tree grows in the western (mainly), central, and eastern part of Iran. The local people use this tree to produce ingredients in some food, jams, and gum (Hatamnia et al., 2014). The gum obtained from this tree consists of oleoresin. This essential oil contains α-Thujene, α-Pinene, Camphorene, Sabinene, β-Pinene, Δ3-Carene Limonene, as well as alpha-tropineol, armanderen, and caprylic acid (Sharifi and Hazell, 2011). The results of previous studies show that the presence of resin in Pistachio has an inhibitory effect on the growth of clostridium botulinum, Staphylococcus aureus, E. Coli, and Streptococcus (Aksoy et al., 2006, Daifas et al., 2004). In another study, the antimicrobial activity of Pistachio atlantica Subsp., i.e., kurdica species were found to have positive results on helicobacter pylori (Sharifi and Hazell, 2011).The aim of the current study was to investigate the inhibition effect of Pistachio atlantica Subsp. Kurdica gum essential oil on staphylococcus aureus, Salmonella, E. Coli, and Listeria monocytogenes.
Materials and Methods
Preparation of the essential oil of Pistachia atlantica gum Subsp. Kurdica: Pistachia atlantica sub sp. Kurdica gum was collected from Kordestan province in Iran. The herbarium approval of the plant was confirmed by the Institute of Medicinal Plants, Medical University of Tehran, Iran. The gum was placed inside the Clevenger along with distilled water and the extraction was carried out by steam distillation method. The ratio of the achieved essence to gum weight was also calculated. The oil was kept at low temperature for further analysis (Mohajeri et al., 2018, Rahimi et al., 2019).
GC-MASS analysis of essential oil: The components of gum EO were isolated by Gas Chromatography/Mass Spectrometry (GC model 9-A, Shimadzu, Japan, and GC/MS model Varian 3400, USA) using a DB-5 column with a length of 30 m and an inner diameter of 0.25 mm. Later, these components were identified by comparing their mass spectrum with the range of combinations found in the computer database and valid compositions. The oven temperature was increased from 60 to 250 °C with an increment rate of 5 °C per minute. At the end, it was kept for 10 minutes at 250 °C. Helium carrier gas with a flow rate of 1.1 mL/min and ionization energy of 70 electron volts was used. The separation ratio was 1 to 50 and the injection volume was 100 μ (Rahimi et al., 2019, Sharifi and Hazell, 2011).
Determination of antimicrobial properties of Pistacia atlantica gum EO by disk diffusion method: In this study, four standard bacterial strains were used including Listeria monocytogenes (PTCC 1298), Escherichia coli (ATCC 2592), Staphylococcus aureus (ATCC 25923), and Salmonella enterica (PTCC 14028). At first, a microbial suspension equivalent to 0.5 McFarland turbidity standards (approximate density of 1.5×10⁸ CFU/mL) was prepared from each strain. Then, 100 µL of each bacterial suspension with a density of 10⁶ CFU/mL was cultured by spreading on the surface of the Mueller-Hinton agar medium. A 5-mm diameter sterile paper disk was placed on the medium and 15 µL of pure EO was injected into the disk. Plates were incubated for 24 hours at 37° C. Then, the diameter of the inhibition zone was measured. All treatments were carried out in triplicate (Akrami et al., 2015).
Data analysis: The experimental data were