Identification of plant growth promoting rhizobacteria in rhizosphere of bamboo thorns with gram methylene blue and lugol staining

Plant Growth Promoting Rhizobacteria is a group of mirorooganisms that can increase plant growth and yield through reactions that occur in the soil, however, the large number of microorganisms contained in the PGPR rhizosphere of bamboo thorns makes it difficult to know which bacteria are the most dominant and most active in influencing plants. Generally, gram staining of bacteria aims to facilitate the observation of bacterial morphology with the aid of a microscope. Bacteria are generally colorless and almost invisible due to the lack of contrast with the water in which they may be present. Staining using methylene blue and lugol is generally needed to see the bacteria clearly. This study aims to determine the effect of using the gram stain test method with methylene blue and lugol in identifying PGPR bacteria from rhizosphere of bamboo thorn. This research was conducted at the Laboratory of Biological Fertilizers and Potential Microbes, Faculty of Agriculture, Hasanuddin University in October-December 2019. The research methods included the manufacture of microorganism planting media, pouring media, planting bacteria using the scatter and scratch method, and the gram reaction test using methylene blue and lugol. The results obtained showed that the use of the gram test with methylene blue and lugol resulted in a blue color which indicated the dominance of the genus Pseudomonas , while the pink/purple color indicated the dominance of the genus Bacillus . Changes in the color of the bacteria to pink/dark purple, the bacteria were gram negative and belong to the Pseudomonas group and there was a change in blue, so the bacteria were gram-positive and were group of Bacillus . Therefore, the use of the gram test with methylene blue and lugol has an optimal effect in detecting microorganisms especially in identifying PGPR.