The inclusion of more sustainable alternatives such as bacterial inoculants is a viable option for the competitiveness of vegetable crops in tropical countries such as Colombia. The economic feasibility of a bacterial suspension of G. diazotrophicus applied to the carrot crop was determined. The native isolate G. diazotrophicus GIBI029 was evaluated and the strain ATCC 49037 was used as a control. The experiment was installed in a subdivided plot design, where the plot was the bacterium G. diazotrophicus (ATCC49037 and GIBI029. The subplot was the concentration of G. diazotrophicus (88×10 6 CFU/mL and 18×10 7 CFU/mL) and, in it, the levels of nitrogen and phosphorus (0% and 100% nitrogen and phosphorus) were assorted. The average weight of the carrot (g) and the yield by quality of the consuming organ (kg/ ha) were evaluated. Through the production cycle, fixed, variable, and total costs were calculated. Benefit / cost ratios higher than 1.46 and net income up to US$ 10,817/ha were achieved. It is possible to efficiently and economically use the native isolate G. diazotrophicus GIBI029 in the search for more sustainable and competitive cultural practices.

Silver nanoparticles have been obtained by colloidal synthesis using two different reducing agents: ascorbic acid and ethylene glycol. The colloids have been characterized by UV-Vis Spectroscopy, atomic absorption and transmission electron microscopy (TEM). The UV-visible spectra show the typical peak with a maximum ranging between 390-420 nm, due to the plasmon resonance of spherical silver nanoparticles. TEM micrographs show non-aggregated spherical silver nanoparticles whit diameters between 30 and 50 nm. The antibacterial effect was tested in three different bacteria cultures: Escherichia coli (gram negative), Staphylococcus epidermidis (gram positive) and dental plaque, which were grown in Mueller-Hinton agar. For comparative purposes the bactericidal effect of silver nitrate was also evaluated. Inhibition index (IIC) was calculated, obtaining satisfactory results for the three kinds of microorganism when silver nanoparticles are used.

Carrot production is expensive since approximately 51% of the total costs are allocated to the nutrition of the crop. Bacterial inoculants are a promising alternative for crop fertilization. This research aimed to evaluate the effect of Gluconacetobacter diazotrophicus on the performance of carrot cultivar “Royal Chantenay” and its interaction with nitrogen and phosphorus fertilization. An experimental design of sub-subdivided plots was applied, where the largest plot consisted of the reference strain (ATCC 49037) and a native Colombian isolate of the bacterium (GIBI029); two concentrations of the bacterium were applied in the subplots (8.8 × 107 and 18 × 107 CFU/mL), and the levels of nitrogen and phosphorus were sorted within each one of them. The best positive effect was observed with the application of G. diazotrophicus ATCC49037 and GIBI029 at a concentration of 18 × 107 CFU/mL without the application of phosphorus or nitrogen in which yields of 37,417 and 30,606 kg/ha were obtained, respectively, exceeding the national average production in Colombia. In contrast, conventional treatment had a yield of 27,909 kg/ha. Additionally, higher quality was evidenced in the product weight with values of 126.48 g (ATCC49037) and 104.98 g (GIBI029), compared with the conventional treatment (93.19 g). G. diazotrophicus was shown to exhibit growth-promoting properties not only in crops such as sugarcane but also in economically important vegetable crops. The results obtained may contribute to the development of a novel microbial inoculant for vegetables under agroecological conditions in tropical areas.