FAPESP Bioenergy Program - Study of the Transference of Fixed Nitrogen from Diazotrophic Bacteria to Sugarcane

Sep 8, 2026

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Research under the FAPESP Bioenergy Program investigates how fixed nitrogen is transferred from diazotrophic endophytic bacteria to sugarcane, aiming to reduce the environmental impact associated with low nitrogen-fertilizer response in this crop. Experiments evaluate protein content and C/N ratio in inoculated versus non-inoculated plantlets under conventional, organic, and control treatments, and assess bacterial effects on nitrogen transport mechanisms. Results highlight treatment-dependent growth and enzyme activity differences, alongside callus co-culture studies to characterize bacterial interference and nitrogenase-related activity.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages2

Reading Time5 min

AccessFree to download

Study objectives and experimental design

Plantlet inoculation and fertilization treatments

Callus co-cultures and protein profiling

Summary of results to date and perspectives

Growth and biomass responses

Nitrate reductase activity and nitrogen transport

Callus responses in co-culture

Future experiments

Main publications

FAPESP BIOENERGY PROGRAM [http://bioenfapesp.org](http://bioenfapesp.org) StudY OF thE tRANSFERENcE OF FIxEd NItROGEN FROM dIAzOtROPhIc BActERIA tO SuGARcANE Heloiza Ramos BARBosA institute of Biomedical sciences / University of são Paulo (iCB/UsP) sugarcane is one of the most important crops in Brazil. This crop has a low response to nitrogen fertilizer, and even small inputs cause environmental impact. The use of biofertilizer as diazotrophic endophytic bacteria and organic fertilizer can decrease this impact. endophytic bacteria live inside plant tissues and do not visibly harm the host. The influence of these bacteria on sugarcane is under investigation in this project. Diazotrophic bacteria may play an important role in the nitrogen nutrition in sugarcane. The aim of the present project is to study the transference of fixed nitrogen from diazotrophic bacteria to sugarcane. To reach this objectives it will be performed: (1) analysis of the protein content and the C/n ratio in plantlets inoculated or not with endophytic diazotrophic bacteria isolated from sugarcane and submitted to different type of treatment: conventional, organic and control and (2) the evaluation of the possible interference of these bacteria on the nitrogen transport mechanism in sugarcane. (3) analysis of sugarcane callus grown in co-cultures with endophytic diazotrophic bacteria to study the bacterial interference on the callus proteins profile. sugarcane callus can be used to evaluate if mixed diazotrophic bacteria can interact with eachother and can also demonstrate the counter effect. The results obtained may contribute with knowledge on cultivation strategies. Thus, biodiversity will be used to the benefit of sustainable cultivation, evaluating the contribution of the nitrogen-fixing bacteria to the sugarcane, as well as the preservation of the soil and for the ecologic equilibrium. SuMMARY OF RESultS tO dAtE ANd PERSPEctIVES The treatments of sugarcane plantlets, after 60 days of incubation, showed that under organic fertilization, inorganic treatment and in control, respectively: -a 3.0, 4.7 and 1.7 fold increase in the height of plantlets -a 15.5, 31.0 and 3.4 fold increase in the fresh weight of plantlets -a 25.5, 106.0 and 4.3 fold higher dry weight sugarcane plants were submitted to 4 treatments: (1) control (no inoculation and no combined nitrogen source); (2) inoculated with Acinetobacter sp. (iCB117) in absence of combined nitrogen source; (3) no inoculation, in presence of nitrate and (4) inoculated with iCB117 and in presence of nitrate. Bacterium inoculated plants showed larger total dry matter, number of leaves and values of Co2 uptake when compared to uninoculated plants submitted to the same nitrogen treatment. The enzyme nitrate reductase was more active in inoculated plants, in the presence of nitrate; in absence of nitrate, inoculated plants showed lower nitrate reductase activity than control. The endophytic iCB117 population was larger in plants treated without nitrate. Using co-cultures, its was possible to evaluate that the influence of one bacterial genus on the callus depends on the bacterial strain; a mixture of two genera enhance the nitrogenase activity. ongoing experiments, carried out in this project, aim to characterise these proteins and verify if there are differences between callus proteins in pure or in co-culture. Future experiments will be carried out considering the Figure 2: Dry matter (A) and leaf nitrate reductase activity (B) measured after 30 (white) and 60 (gray) days in plants under different treatments presence or absence of inoculants and type of fertilization. 0 Control iCB117 nitrate iCB117+nitrate Treatment leaf nitrate Reductase Activity Control iCB117 nitrate iCB117+nitrate Treatment MAIN PUBLICATIONS Reinhardt Él, Ramos Pl, Manfio G P, Barbosa HR, Pavan C, Moreira Filho CA. 2008. Molecular characterization of nitrogen-fixing bacteria isolated fr

FAQs

What is the main objective of the project?

To study the transfer of fixed nitrogen from diazotrophic bacteria to sugarcane, including how these bacteria may influence nitrogen transport mechanisms.

How were sugarcane plantlets treated in the experiments?

Plantlets were compared across four treatments: control (no inoculation, no combined nitrogen), inoculation with Acinetobacter sp. (iCB117) without combined nitrogen, no inoculation with nitrate, and inoculation with iCB117 with nitrate.

What did the summary results indicate about nitrate reductase activity?

Nitrate reductase was more active in inoculated plants under nitrate, while in the absence of nitrate inoculated plants showed lower activity than the control.

Sep 8, 2026

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