Maize (Zea mays L.) is one of the highly demanding food plants in Indonesia but the production is currently not sufficient to meet the community's needs, so that efforts to import maize in Indonesia are still frequently carried out. Meanwhile, the maize production who mostly produced by local farmer mainly cultivated on marginal land which is threatened by drought stress. Efforts should be make to increase maize productivity on dry land by utilization of rhizobacteria isolated from maize rhizosphere. This study aimed to determine the types of rhizobacteria from the diversity of microbes that potentially increase the productivity of maize plants. This study used 2 isolation methods, namely isolation on gram-positive and gram-negative, followed by electrophoresis and PCR with primers of 27F and 1492R. Then the PCR results were sequenced and analyzed using Mega X. The sequencing results compared with Genbank at NCBI showed 10 isolates that have been shown to have closeness to several strains of bacteria, such as Raoultella terrigena, Serratia marcescens, Serratia nematodiphila, Enterobacter hormaechei, Enterobacter cancerogenous, Enterobacter cloacae, Enterobacter asburiae, Citrobacter murliniae, Pseudomonas fluorescens. depicted in phylogenetic analysis. Based on the phylogenetic analysis, the L5S2 10-7 isolate has similarities with the Enterobacter asburiae strain, while the L2S1 10-6 isolate is closely related to the Enterobacter cancergenous strain, Then the Citrobacter murliniae strains were closely related to L5S5 10-8 and L1S3 10-7 isolates. In addition, the Enterobacter hormaechei strain also has a close relationship with isolate L3S1 10-8, and the Raoultella terrigena strain has a close relationship with isolate L5S2 10-6. The L1S5 10-6 and L3S5 10-7 isolates had the same similarity based on genetic characters but had different abilities in helping the performance of plants belonging to the rhizobacteria group.

Maize is one of the strategic food crops and has economic value and could be developed because of its position as the main carbohydrate and protein source after rice. This could be a reference for us to increase maize cultivation, seeing the role of maize is quite large, and the availability of maize is less stable every year. maize can grow optimally on productive land and marginal land, but at this time more productive land is used for rice production. One alternative for maize production is on marginal land especially dryland. The main problem in dryland is limited water. One way to overcome this is by inoculating Rhizobacteria which can increase the growth and resistance of maize to drought. Rhizobacteria possess tremendous potential for modulating the physiological response to water deprivation, thus ensuring plant survival under such stressful conditions. The research aimed to find rhizobacteria have secondary metabolite for resistance to drought. Rhizobacteria exploration and secondary metabolite isolation was conducted at University of Muhammadiyah Malang. The research results have obtained 10 isolates capable of synthesizing extracellular secondary metabolites: osmoprotectants, phytohormones, and organopesticides that can be used by plants. The results of the analysis by GS-MS (Gas Chromatography-Mass Spectrometry) rhizobacteria showed that three compounds were synthesized. The osmoprotectants compound synthesize ware found namely: (a) (2E)-3,7-dimethylocta-2,6-dienal 16.66%;(b) (E)-hept-2-enal12.55%;(c)2-methylsulfanylethanamine 5.34%; (d) 1,3,5-trimethoxybenzene 4.42%. It is also capable of synthesizing phytohormones: (a) cinnolino [4,3-b] quinoxaline 6.00%; (b) 1-methyl-2-phenylindole 5.90%; (c) 1H-Indole 3.64%; (d) N-2-Fluorenylperfluorpropionamid 3.02%. These rhizobacteria were also able to synthesize: (a) 2-chloro-4-methoxy phenol 11.32%; (b) (E)-non-2-enal 9.87%; (c) 4-chloro-2,6-dipyridin-2-ylpyridine 7.07%; (d) 2-(4-chlorophenyl) hexane nitrile 6.45%. The Osmprotectant compounds aim to protect cells from drought conditions, phytohormones to stimulate plant growth and organopesticides to overcome pests and diseases.