Isolation and Characterization of Cellulolytic Bacteria and Phosphate Solubilizing Bacteria from the Rhizosphere of Muli Banana Plants (Musa acuminata) in Labuhan Ratu District, Bandar Lampung

Muli banana (Musa acuminata) from Lampung requires attention to the availability of phosphate in the soil, as phosphate is one of the most important elements for banana plant growth. To provide dissolved phosphate in the soil, phosphate-solubilizing bacteria (PSB) are needed. Cellulolytic bacteria can provide glucose as a carbon source for PSB. This research aims to isolate and characterize PSB and cellulolytic bacteria from the rhizosphere of Muli banana in Labuhan Ratu district, Bandar Lampung. This research was carried out using soil sampling, bacterial isolation, the selection of potential bacteria, and morphological, physiological, and biochemical characterization. The results showed that out of 5 isolated PSB colonies, BPF4 and BPF8 had the highest phosphate solubility index, reaching a value of 3. The characteristics of the BPF4 and BPF8 are different from each other. Among the 3 colonies with cellulolytic ability, the isolates with the highest cellulolytic activity index were isolates BS1 and BS7, which had an SAI value of 0.58. The morphological results of each cellulolytic bacterial colony varied. The cellulolytic bacteria showed coccus-shaped cells and were Gram-positive in BS1, whereas BS7 was Gram-negative. There was no spreading growth in the PSB motility test, whereas all cellulolytic bacteria exhibited motility. The glucose fermentation test only showed color change in isolates BPF2, BPF5, and BPF8, with no appearance of bubbles. Almost all isolates tested positive in the catalase test, with only isolate BS8 not showing any foam.