Lichens are generally characterized as the symbiotic association of a mycosymbiont and a photosymbiont, however lichen-associated bacteria have been recently described as a third partner. The objectives of this study were to isolate bacteria from lichen and to screen for their biological activities. Total of 117 bacterial isolates were obtained from Parmotrema sp. growing on para rubber tree in Chiangdao, Chiangmai. These bacteria were identified using 16S rRNA gene sequence. They were belonged to the genera of Acinetobacter, Pseudomonas, Bacillus, Paenibacillus, Lysinibacillus, Brevibacillus, Staphylococcus and Virgibacillus. These lichen-associated bacteria were then investigated for antimicrobial activities, hydrolytic enzyme production, nitrogen fixation, indole-acetic acid (IAA) production and phosphate solubilization. Their antibacterial activities against Bacillus cereus, Escherichia coli, Enterobacter cloacae, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella typhi, Shigella sonei, Staphylococcus aureus and Xanthomonas camprestis were preliminary performed by the spot on lawn method. It was found that thirty-seven isolates exhibited the antagonistic activity against Staphylococcus aureus. Cell free supernatant of these bacteria were then investigated the antibacterial activity by agar well diffusion method. Only nine isolates of genus Bacillus expressed the inhibitory effect on S. aureus growth. Antifungal activities against Ascomycete sp. LD01-2, Aspergillus sp. L4.1D, Diaporthe sp. LD05-5 and Fusarium sp. L5.2A which isolated from longan including Aspergillus niger, A. flavus and F.solani were investigated. Total of 35 isolates comprising of the genera of Bacillus, and Paenibacillus showed the inhibitory effect on fungal growth.
The lichen-associated bacterial isolates were screened for hydrolytic enzymes production. It was found that one hundred and one isolates showed hydrolyzing zones by the carboxy methyl cellulose (CMC) congo red plate technique. According to CMCase activity, the highest cellulase producing bacterium from lichen was Bacillus amyloliquefaciens with 77.32 mU/ml. Ninety-eight produced proteolytic enzyme. The highest protease activity was obtained by Bacillus sp. at 32.45 U/ml. Among these, the isolate of B. velezensis gave the highest amylase activity with 0.78 U/ml. Only 8 isolates belonging to Bacillus and Paenibacillus showed the capacity for chitinolytic enzyme. Sixty five isolates of bacteria comprised of Acenitobacter, Bacillus, Brevibacillus and Paenibacillus, showed the ability to solubilize phosphate. Results showed that B. megaterium LC106 and LC56 obtained the significantly highest solubilizing abilities of Ca3 (PO4)2, about 89.0 and 88.1 ?g/ml, respectively. According to the growth in nitrogen free medium, sixty-six isolates belonging to Acinetobacter, Bacillus, Lysinibacillus, Paenibacillus and Staphylococcus, were able to fix nitrogen. Sixty-one isolates showed the IAA production in range of 0.52-22.32 ?g/ml and B. megaterium released the significantly highest amount of IAA. These results showed that lichens are the new sources of potential bacteria for pharmaceutical, industrial and agricultural uses