We investigated the ability of the aquatic fern Azolla to take up ciprofloxacin (Cipro), as well as the effects of that antibiotic on the N-fixing process in plants grown in medium deprived (-N) or provided (+N) with nitrogen (N). Azolla was seen to accumulate Cipro at concentrations greater than 160 μg g⁻¹ dry weight when cultivated in 3.05 mg Cipro l⁻¹, indicating it as a candidate for Cipro recovery from water. Although Cipro was not seen to interfere with the heterocyst/vegetative cell ratios, the antibiotic promoted changes with carbon and nitrogen metabolism in plants. Decreased photosynthesis and nitrogenase activity, and altered plant's amino acid profile, with decreases in cell N concentrations, were observed. The removal of N from the growth medium accentuated the deleterious effects of Cipro, resulting in lower photosynthesis, N-fixation, and assimilation rates, and increased hydrogen peroxide accumulation. Our results shown that Cipro may constrain the use of Azolla as a biofertilizer species due to its interference with nitrogen fixation processes.

In this study, different nitrogen doses (0, 16, 48, 64, 80, and 96 kg ha⁻¹) from two sources, biofertilizer (from anaerobic digestion of cattle wastewater) and urea, were applied to cultivate two sugarcane varieties (RB 867515 and SP 803280). °Brix values higher than 21% were obtained with application of 80 kg ha⁻¹ from biofertilizer. The mean productivity of the cultivar RB 867515 using biofertilizer was 147.5 ton ha⁻¹, while from urea it was 136.87 ton ha⁻¹. The cultivar SP 803280 produced an average yield of 152.25 ton ha⁻¹ when applying biofertilizer and 154.37 ton ha⁻¹ with use of urea. Significant differences (P ≤ 0.05) between the use of biofertilizer and urea were detected for cultivar RB 867515 in terms of crude protein concentration. The application of 80 kg of N ha⁻¹ was considered the ideal dose, corresponding to fertirrigation blades of 54 mm of biofertilizer. The experiment showed that the biofertilizer formulation analyzed can replace urea as a nitrogen source for growing sugarcane. Graphical Abstract ᅟ

In the province of South Kivu (Democratic Republic of Congo), warm and humid climatic conditions favor the development and spreading of phytopathogens. The resulting diseases cause important losses in production both in crop and after harvest. In this study, we wanted to evaluate the potential of Bacillus amyloliquefaciens as biocontrol agent to fight some newly isolated endemic fungal pathogens infesting maize. The strain S499 has been selected based on its high in vitro antagonistic activity correlating with a huge potential to secrete fungitoxic lipopeptides upon feeding on maize root exudates. Biocontrol activity of S499 was further tested on infected plantlets in growth chamber and on plants grown under field conditions over an entire cropping period. We observed a strong protective effect of this strain evaluated at two different locations with specific agro-ecological conditions. Interestingly, disease protection was associated with higher yields and our data strongly suggest that, in addition to directly inhibit pathogens, the strain may also act as biofertilizer through the solubilization of phosphorus and/or by producing plant growth hormones in the rhizosphere. This work supports the hope of exploiting such technologically advantageous bacilli for the sake of sustainable local production of this important crop in central Africa.