Cultivation of Azospirillum brasilense in Vinasse and Potential Use in Fertigation

Abstract

Vinasse, residue from the sugar-energy sector, has been applied as a fertilizer in sugarcane fields due to its nutritional characteristics, which may reduce nitrogen fertilization, especially if associated with diazotrophic bacteria. The objective was to evaluate the use of vinasse as culture medium for Azospirillum brasilense and the chemical changes caused in the residue after bacterial colonization. The experimental design was completely randomized with 9 treatments: T0-control (nutrient broth DYGs inoculated with A. brasilense); T1- 100% vinasse inoculated with A. brasilense; T2- 75% vinasse inoculated with A. brasilense; T3- 25% vinasse inoculated with A. brasilense; T4- 50% vinasse inoculated with A. brasilense; T5- 100% vinasse; T6- 75% vinasse; T7- 25% vinasse and T8- 50% vinasse. Microbial growth was evaluated in a spectrophotometer, by turbidimetry (700nm). Chemical characterization of vinasse was carried out before bacterial inoculation and on days 1, 3, 5 and 7 after inoculation according to the methodologies of the Standard Methods for the Examination of Water and Wastewater 22 ND for the elements nitrogen (4500-Norg), phosphorus (4500-P), potassium (3030-A) and calcium (3500 Ca-B). The determination of organic matter was carried out in accordance with the technical standard NBR 13600. The bacteria A. brasilense survived and multiplied in sugarcane vinasse, causing changes such as the increase in the levels of phosphorus and nitrogen and the reduction of the organic load, mainly in pure vinasse (100%), indicating that the viability of this practice for the application of these organisms in the culture of sugar cane via fertigation.

INOCULAÇÃO DE Azospirillum brasilense VIA VINHAÇA NO CULTIVO DE ALFACE

“…A inoculação da bactéria Azospirillum brasiliense, provavelmente contribuiu para esses resultados, segundo Hungria (2011), várias pesquisas podem comprovar a eficiência dessa bactéria para as plantas, incluindo aumento de raiz, maior altura de planta, maior coloração por conta do acúmulo do teor clorofila e maior acúmulo de água na planta. Silva et al (2020) analisando a inoculação de diferentes concentrações de vinhaça com Azospirillum brasilense verificaram que as bactérias sobreviveram e se multiplicaram na vinhaça de cana-de-açúcar, ocasionando alterações como o aumento dos teores de fósforo e nitrogênio e a redução da carga orgânica, principalmente em vinhaça pura (100%), indicando que a viabilidade desta prática para aplicação destes organismos via fertirrigação. Estes resultados corroboram com o observado nesta pesquisa, melhor produtividade e desenvolvimento das plantas de alface fertirrigadas e inoculadas.…”

“…Um resíduo que a muitos anos vem sendo empregado na fertirrigação da cultura da cana-de-açúcar e que hoje vem sendo avaliado em outras culturas como em hortaliças, é a vinhaça (MEDINA et al;2020). A vinhaça é um resíduo líquido orgânico resultante da produção de álcool pelo setor sucroenergético a partir da cana-de-açúcar (MARQUES; PINTO, 2013).…”

Biotechnological production of plant inoculants based on nitrogen-fixing bacteria

“…Azopirillum brasilense Az39 was grown at 32±1 °C with an agitation rate of 140 rpm for three days using the modified NFb medium (Larraburu et al, 2016). Vinasse is a significant by-product of a sugar-ethanol industry, being generated at a rate of 9-14 l per one liter of ethanol produced (Silva et al, 2020). It is usually valorized as a fertilizer in sugarcane fields due to its nutritional characteristics, which may reduce requirements for nitrogen fertilization, especially if associated with diazotrophic bacteria.…”

“…It is usually valorized as a fertilizer in sugarcane fields due to its nutritional characteristics, which may reduce requirements for nitrogen fertilization, especially if associated with diazotrophic bacteria. The study by Silva et al (2020) investigated the possibility to use a vinasse-based medium (100 % vinasse, or vinasse: distilled water ratios 75:25, 50:50, 25:75) for biomass production of Azospirillum brasilense. The cultivations were carried out at room temperature under agitation conditions (120 rpm) for seven days.…”