Identification of the morphological features of indigenous microbial from bauxite residue disposal areas in Indonesia

The increasing amount of annual red mud generation is becoming a global concern because of the environmental problems caused by its high metal content, alkalinity, and salinity. To manage red mud deposits, various green technologies have been implemented, such as phytoremediation and bioremediation. Accordingly, this study aimed to assess the morphological features of indigenous microbes in bauxite residue disposal areas (BRDA) in Indonesia. Using Gram staining method and microscopic analysis, indigenous microbial species were characterised based on morphological features such as colony profile, colour, size, margin, elevation and cell shape. As many as 10 isolates of indigenous microbes were successfully identified. All isolated were Gram positive and mostly white. The shape of colonies varied from irregular, circular, and filamentous with flat elevation, whereas the cell shape was identified as rod-shape and round-shape. Based on the similarity of the morphological characteristics of these microbes, there are five suspected genus, i.e., Micrococcus, Microbacterium, Bacillus, Cylindrogloea, Eubacterium, and Staphylococcus.