Molecular characteristics of vermicompost and their relationship to preservation of inoculated nitrogen-fixing bacteria

• Published in: Journal of analytical and applied pyrolysis Vol. 104; pp. 540 - 550
• Main Authors: Martinez-Balmori, Dariellys, Olivares, Fábio Lopes, Spaccini, Riccardo, Aguiar, Kamilla Pereira, Araújo, Marcelo Francisco, Aguiar, Natália Oliveira, Guridi, Fernando, Canellas, Luciano Pasqualoto
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2013
• Subjects: alcohols; alkanes; alkenes; Beneficial microorganisms; carbohydrates; cattle manure; Diazotrophs; esters; fatty acids; filter cake; Herbaspirillum seropedicae; hydrophobicity; lignin; microbial activity; Microbial survival; nitrogen; nitrogen-fixing bacteria; organic matter; propionic acid; pyrolysis; Pyrolysis off-line; steroids; Structural–activity ratio; sugar industry; terpenoids; Thermochemolysis; vermicomposting; vermicomposts; Structural–activity ratio; Beneficial microorganisms; Thermochemolysis; Microbial survival; Diazotrophs; Pyrolysis off-line
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2013.05.015

•We monitor changes on molecular composition over the vermicompost process.•The increment of hydrophobic compounds occurs with maturation.•Microorganisms’ persistence was related with vermicompost chemical composition.•Understanding chemical nature makes possible increase vermicompost value and activity. The chemical nature of organic matter during the process of vermicomposting of cattle manure and filter cake from a sugar factory was characterized by thermochemolysis. The pyrolysates were mainly constituted of lignin moieties from propanoic acid units and short-chain (<C20) fatty acids (as methyl esters); alkanes, alkenes, terpenes and steroids were minor compounds. Nitrogen containing compounds were noticeable in filter cake vermicompost (VC) as were carbohydrate moieties. Despite thermochemolysis had shown low sensitivity for carbohydrates, the presence of a number of carbohydrate derivatives was indicative of extensive biological transformation of organic matter during vermicomposting. A high content of long-chain alcohols was found only in filter cake VC. At the end of VC maturation, the content of hydrophobic compounds (lignins plus fatty acids) in filter cake residues was higher than in cattle manure. This mature VC exhibited the highest natural density of culturable diazotrophic bacteria compared to cattle manure VC (approximately 104timescellsg−1VC), and when the diazotrophic bacterium Herbaspirillum seropedicae was introduced to both types of VC, the population numbers were higher in filter cake VC at 10 months of storage after inoculation. We found an apparent relationship between molecular characteristics of organic matter and the harboring or preservation of diazotrophic bacteria introduced to VC, which is a step toward understanding the relationship between the molecular characteristics of organic matter and the microbial activities.