Talitha Widiatningrum, Lina Herlina, Kiki Rahma Aprilia, Fadhlika Nurhidayah, Fita Fatimah Hartanti, Silvia Dewi Ula Fatma
Delta is a bulk mass of river sediment that encompasses a variety of vegetation and soil microorganisms in beneficial relationships. The Kaligarang river delta in Semarang, Indonesia, has typical weed vegetation of Ageratum conyzoides, Galinsoga parviflora, Eleusine indica, and Kylinnga brevifolia, with impressive growth that may have been encouraged by rhizobacteria. Therefore, this study aimed to characterize rhizobacteria from the aforementioned deltaic weed vegetation, beginning with colony and cell morphology, biochemical and phytohormone analyses, and genotypic analysis of the notable performer. The result displayed distinctive colonies from A. conyzoides and G. parviflora rhizosphere samples with 3 of each. Meanwhile, K. brevifolia and E. indica rhizosphere unveiled 4 and 2 isolates, respectively. Most of the colonies were Gram-positive bacilli with circular or punctiform forms, entire edges, convex elevations, and the potential for catalase, starch hydrolysis, nitrogen fixation, phosphate solubilization, potassium solubilization, and auxin production. One of the A. conyzoides isolates achieved full biochemical competence and the highest auxin enhancement during 48 h of incubation without endospores. The sequence homology and phylogenetic tree analyses of the 16S rRNA gene suggested that the colony was B. cereus. The isolate characterization was in line with other research on B. cereus colony features and the tryptophan-dependent indole-3-acetic acid biosynthesis pathway. © 2026, Centenary University. All rights reserved.
Universitas Negeri Semarang, Faculty of Mathematic and Natural Science, Biology Department, Semarang, 50229, Indonesia
