1 Abstract—The objective of this research was focused on investigating in vitro antimicrobial activity of Phellinus linteus fruiting body extracts on Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. Phellinus linteus fruiting body was extracted with ethanol and ethyl acetate and was vaporized. The disc diffusion assay was used to assess antimicrobial activity against tested bacterial strains. Primary screening of chemical profile of crude extract was determined by using thin layer chromatography. The positive control and the negative control were used as erythromycin and dimethyl sulfoxide, respectively. Initial screening of Phellinus linteus crude extract with the disc diffusion assay demonstrated that only ethanol had greater antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. The MIC assay showed that the lower MIC was observed with 0.5 mg/ml of Pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus and 0.25 mg/ml. of Escherichia coli and Staphylococcus aureus, respectively. TLC chemical profile of extract was represented at R f ≈ 0.71-0.76. Keywords—Staphylococcus aureus, Phellinus linteus, methicillin-resistant Staphylococcus aureus, antimicrobial activity, Escherichia coli. I. INTRODUCTION N recent years, the development of new antibiotic drugs is a key issue for antimicrobial because microorganism resistant to current drugs, especially opportunistic pathogens, can cause mortality [1]. Antibiotic resistance is seen in a range of pathogenic and non-pathogenic bacteria; however, Methicillin-resistant Staphylococcus aureus (MRSA) is the most commonly reported. There are very few drugs on the horizon. This problem is not just confined to the hospital or health care environment. Nowadays, many antibiotic-resistant microorganisms are seen in the community and also among animals. This has resulted in a number of changes in practice and intenseness of the data made available to those able to prescribe antibiotics and natural agent. Hence, there has been an increasing focus on developing novel research into natural antibiotics and more targeted treatment strategies, by study clinical trial to assay the efficacy of secondary metabolites; however, there is still a need for in vivo animal studies to appropriately evaluate the antibiotics for the treatment of multidrug resistant bacteria, especially screening the active S. Techaoei, K. Jarmkom, P. Eakwaropas and W. Khobjai are with the Department of Thai Traditional Medicine, Thai Traditional Medicine College, Rajamangala University of Technology Thanyaburi, Pathum Thani, 12130 Thailand (phone: +66 25921999, fax: +66 25921900, e-mail: surachai_te@rmutt.ac.th, khemjira_j@rmutt.ac.th, pattaranut_e@rmutt.ac.th, warachate_k@rmutt.ac.th). compounds with good pharmacologic properties and drug safety, with a return to traditional remedies medicines. The traditional folk herbal medicine as an alternative antimicrobial therapy has attracted substantial attention due to its low toxicity and costs as well as wisdom knowledge. Phellinus linteus (Fig. 1), a basidiomycete, is a species of medical mushroom whose fruiting body is commonly called Krathin Phiman in Thailand and sangwhang in Taiwan. This mushroom has been widely used in ancient herbal medicines and alternative herbal therapy in oriental countries including China, Japan, Korea, and Thailand [3]. Phellinus linteus was previously described as immunodulatory, antitumor [2], [4], [5], antioxidant, anti-inflammatory [6], and antimicrobial activity [7]. Therefore, the antimicrobial activity of P. linteus with Methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli were evaluated, together with their chemical profile. Fig. 1 The fruiting of P. lineus [8] II. MATERIALS AND METHODS A. Fungal Cultivation The fungal mycelial was cultivated on potato dextrose agar (PDA) by placing agar blocks of actively growing pure fungal culture (Fig. 2) in 250 ml Erlenmeyer flasks containing 100 ml of the medium. The flasks were incubated at 30 °C for four weeks with periodical shaking at 100 rpm. B. Analysis of Radial Growth The fungal strain Phellinus linteus kept in tested tube containing PDA slant culture tubes in refrigerator was inoculated in Petri dishes with PDA at least for 14 days. After incubation, mycelial fragment (0.8 cm diameter) of the strains under study was transferred to Petri-dishes using 20 ml of PDA and incubated at 30 °C. Fungal growth was determined S. Techaoei, K. Jarmkom, P. Eakwaropas, W. Khobjai An Alternative Antimicrobial Approach to Fight Bacterial Pathogens from Phellinus linteus I World Academy of Science, Engineering and Technology International Journal of Bioengineering and Life Sciences Vol:11, No:5, 2017 351 International Scholarly and Scientific Research & Innovation 11(5) 2017 scholar.waset.org/1307-6892/10006905 International Science Index, Bioengineering and Life Sciences Vol:11, No:5, 2017 waset.org/Publication/10006905