Effect of Benzoin Resin Fumes on Indoor Environmental Microbes

Received: 18-Nov-2020 Accepted Date: Dec 21, 2020 ; Published: 28-Dec-2020

Introduction

Indoor environments are the most important environmental factors that can influence health. The air quality of indoor environments is one of the main factors that affect the health, safety, and productivity of people. The presence of microorganisms, including bacteria, molds, and viruses, is one of the major problems that affect the quality of indoor air [1,2]. People spend 90 % of their time indoors breathing an average of 14 m3 of air per day [3,4]. As such, people are highly exposed to indoor microorganisms. A review published by the World Health Organization on some epidemiological studies showed adequate evidence for the association between indoor dampness-related factors and a wide range of effects on respiratory diseases, including asthma development, asthma exacerbation, current asthma, respiratory infections, upper respiratory tract symptoms, cough, wheeze, and dyspnoea [1].

Ceremonies were performed in the past to purify the environment by burning wood and odoriferous medicinal herbs [5]. Since the earliest times, the burning of frankincense and myrrh in places of worship for religious purposes had hygienic functions, can refine smell, and minimize pollution by purifying indoor air [5]. The fumigation of an operating theatre with fumes of mustard, butter, and salt may be an early kind of “antisepsis” of the air, although it had been additionally performed to eliminate evil spirits [6].

Nowadays, different traditional practices involve the use of fumigation smokes within confined spaces to purify or disinfect the air and to clean the environment.

The traditional use of fumes of resins in Arabic countries has many purposes: resin fumes are used for spiritual purposes, to provide a pleasant smell in homes and eliminate bad smells, improve the mood and eliminate negative energy, feelings of fatigue, lethargy and laziness and respiratory problems, such as colds and flu [7].

Recent studies have proven the efficacy of holy stick fumigation against infectious bacteria, as well as the efficacy of medicinal smoke on airborne bacteria [5,6]. Many substances, including Jawi (benzoin resin), oud, frankincense, aromatic wood, herbs, flowers, essential oils, and perfume, are used to produce incense and to eliminate undesirable odors in an indoor environment.

Jawi is the most common fume incense used in daily traditional practice in Arabic countries. Jawi is used for its aromatic scents.

The two main types of benzoin resins are Sumatra benzoin and Siam benzoin, which are available in markets. These two varieties grow in different geographical areas. Siam benzoin grows in Laos, whilst Sumatra benzoin grows in Indonesia [8]. The three types of Styrax benzoin resins are red, grey, and white, which contains compounds, such as benzoic acid, benzaldehyde, and benzyl benzoate, exhibiting bactericidal, germicidal, antiviral, and fungicidal properties. The areas exposed to the smoke of benzoin resin are disinfected. Benzoin oil also has anti-flatulence and carminative properties [9,10]. The antimicrobial effects of some known constituents of the different type’s benzoin resin have been studied in detail by extracting essential oils from resin.

The obtained extracts were tested against two types of pathogenic bacteria, namely, Staphylococcus aureus and Escherichia coli. The results showed that the extracts have good antioxidant and antibacterial effects [11].

Regarding the effect of resin fume on microbes, several studies have investigated the effect of burning incense and its smoke on microbes by evaluating their effect on bacteria and fungi by using a smoke chamber or air samplers [12-15] inside a confined area in the laboratory.

In the present work, we selected white benzoin resin (Al-Jawi) as a subject because of its widely popular use as traditional incense fume in Saudi Arabia. We tested the direct effects of incense fume on selected clinical pathogenic bacteria isolates collected from the hospital and examined its short-term effects on cleaning and sterilizing confined university premises from environmental microbes.

Methodology

The study was carried out in the College of Applied Medical Sciences, Dawadmi, Shaqra University between March and November 2019.

Samples

White benzoin resins: Al-Jawi is a balsamic resin obtained from the bark of several species of trees in the genus Styrax [8]. The fresh samples used in this study were obtained in March 2019 from a local market in Dawadmi City (Figure 1) and were used in the crude form similar to the ones traditionally used in the homes on a daily bases.

Figure 1. White benzoin resin (crude sample purchased from Dawadmi City market, KSA)

Bacterial isolates: Five strains of bacteria (E. coli, S. aureus Klebsiella pneumoniae, Enterobacter aerogenes, and Pseudomonas aeruginosa) isolated from clinical cases in the General Hospital of Dawadmi City were used in the study.

In addition to these pathogenic bacteria, airborne microbial isolates were collected from different university premises using the settle plate method.

The isolated microbes were incubated aerobically at 37°C for 24 h. Based on the morphological analysis and the Gram reaction, two isolates were considered for further analysis. One desecrate colony from each type was obtained and dissolved in 1 mL of sterile physiological saline. Suspensions were adjusted to standard turbidity (0.5), which corresponds to approximately 1.0 × 10⁸ CFU/ml. An automated device (VITEK^® 2, BioMérieux) was used to identify the microbial isolates. The identified isolates were S. aureus and Candida albicans.

Experimental Setting

The experiments were conducted in two phases: the first phase aimed to test the effect of the white benzoin resin on the known clinical bacteria isolates and airborne environmental isolates under laboratory conditions. In the second phase, the effect of resin fumes was assessed in confined places in university premises to determine the effect of fumes on total air microbial count before and after burning the resin in these places.

First phase: The clinical isolates were used for the in vitro determination of the antibacterial efficiency of crude resin following the method of Fontes et al. with some modifications (nutrient agar was used instead of blood agar) [16]. Bacteria were inoculated on nutrient agar plates and incubated aerobically at (35 ± 2)°C for (18 to 24) h. The standardized inoculum was prepared using a direct colony suspension by making a saline suspension of isolated colonies selected from nutrient agar plates. Each bacterial suspension was adjusted to 105 CFU/mL. An aliquot of 10 μL of this suspension was inoculated by lawn culture in four nutrient agar plates with a final concentration of 10³ CFU/mL. Then, the plates were divided into four groups. The first group was exposed to the benzoin resin fumes by burning of 1 g of benzoin resin in a sealed container with a dimension of 50 cm × 50 cm × 50 cm for 30 min. The second and third groups were exposed to incense fume for 45 min and 90 min. The resin was burned using an electric incense burner provided with a hot plate (without using charcoal). The fourth group of plates was the negative control group. Then, the plates were incubated at 37°C for 24 h, and the CFU for each plate was determined using a colony counter.

Second phase: The effect of white benzoin resin fumes on the airborne microorganisms in selected rooms in the university was determined by passive sampling. The rooms exposed to the resin fumes were the library, the students’ restroom, one classroom, and the microbiology laboratory. The effects of the incense fumes on the total microbial count in the air in the selected areas were examined. Those rooms were occupied occasionally by 20-30 students. The dimensions of the rooms were 8 m × 10 m × 3.5 m. Sampling was performed early in the morning before the rooms were used by the students, and the test was performed in triplicate.

Passive sampling via the gravity method (settle plate method) was performed to determine the total microorganism count (bacterial and fungal) in the air. This number corresponds to the number of CFU counted on a petri dish with a diameter of 9 cm placed according to the 1/1/1 scheme (for 1 h, 1 m above the floor, approximately 1 m away from walls or any major obstacles). Sampling was performed two times before and after burning the incense by using nutrient agar plates [17].

Exactly 10 g of the crude benzoin resin was burned in the nave with sealed windows and doors to prevent unexpected airflow and allow the aromatic atmosphere to form. Then, passive sampling was performed as previously mentioned. Each plate was incubated at the end of the test at 37°C for 48 h. Then, the total number of CFU was determined at each plate by using a colony counter.

Conclusion

In conclusion, our results showed that benzoin resin fume minimized microbial hazards and improved the air quality of the university premises. The fumes reduced indoor environmental microbe isolates by 70%-75% and clinical isolates from the hospital by 100%.

The use of incense fumes can prevent bacterial growth, sterilize the environmental air, and promote a healthy atmosphere by minimizing airborne transmission.

This study suggests the direct effect of crude incense on some environmental microbial isolates, such as bacteria and fungi. However, further studies are needed to determine the effects of incense on airborne viruses, such as coronaviruses, which present a major pandemic health problem at present.

Declerations

Acknowlegement

The authors would like to express their appreciation to the Laboratory Department in Dawadmi general hospital for providing the bacterial Clinical Isolates used in this study. Also, they would like to convey appreciation to Prof. Asaad Khalid MA Ahmed, Substance Abuse and Toxicology Research Center, Jazan University, Saudi Arabia for his critical reading of this manuscript.

Conflict of Interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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