Bioefficacy Test of Different Chemotherapeutic Substances against Aspergillus sp. and Chrysosporium sp. Contaminants of Tissue-Cultured Abaca (Musa textiles NEE.) during Initial Stage of Micropropagation

Abstract

The study was conducted at the Tissue Culture Laboratory and Crop Research Laboratory of the University of Southeastern Philippines to test the efficacy of selected antibiotics and antifungal agents in the elimination of the common fungi contaminant of tissue-cultured abaca meriplants during initial stage of propagation on the Murashige and Skoog medium. Microbial symptoms were observed based on their colony shape, colony margin/ elevation and colony color in 20 bottle test media during one month (Initial stage) observation period. The technique of James and Natalie was adopted for identification of the unknown isolated fungi. The species encountered were identified and characterized following the technique of James and Natalie. The Poisoned Food Technique for Antibiotic Sensitivity Testing for Fungi was used. The experiment was laid-out in completely randomized design (CRD) with five treatments replicated three times. There were five plates per replicate for a total of 75 plates. The treatments were: T1-Control (No treatment); T2-Streptomycin (200 mg·L-1); T3-Nystatin (1 ml·L-1); T4-Streptomycin (200 mg·L-1) + Nystatin (1 ml·L-1); and T5-Benomyl (Chemical check, 100 mg·L-1). Study showed that the common contaminants of tissue-cultured abaca were fungal colonies such as Aspergillus sp. and Chrysosporium sp. like fungus appeared on the 10th day and 12th day after initiation, respectively with a total of 15% rate of occurrence. Result of in vitro test likewise showed that T5 - Benomyl (Chemical check, 100 mg·L-1) significantly inhibited the growth of Aspergillus sp. T3 - Nystatin (1 ml·L-1) also inhibited the growth of fungal contaminants same as Chrysosporium sp. These fungal species were found to cause death of the culture biological material by some probable sources of contaminations, such as handling of plant materials, culture vessels and the laboratory. The result of the study suggests that both Benomyl (Chemical check, 100 mg*L-1) and Nystatin (1 ml*L-1) can be used to inhibit growth of fungal contaminants, such as Aspergillus sp. and Chrysosporium sp. like fungus.