Journal of Analytical and Applied Pyrolysis 104 (2013) 540–550 Contents lists available at ScienceDirect Journal of Analytical and Applied Pyrolysis journa l h om epage: ww w.elsevier.com/locate/jaap Molecular characteristics of vermicompost and their relationship to preservation of inoculated nitrogen-fixing bacteria Dariellys Martinez-Balmori a,b , Fábio Lopes Olivares a , Riccardo Spaccini c , Kamilla Pereira Aguiar a , Marcelo Francisco Araújo a , Natália Oliveira Aguiar a , Fernando Guridi b , Luciano Pasqualoto Canellas a,∗ a UENF – Universidade Estadual do Norte Fluminense Darcy Ribeiro, Núcleo de Desenvolvimento de Insumos Biológicos para a Agricultura (NUDIBA), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil b Departamento de Química, Universidad Agraria de La Habana, San José de las Lajas, Cuba c Dipartimento di Agraria, Università di Napoli Federico II, Via Università 100, 80055 Portici, Italy a r t i c l e i n f o Article history: Received 14 February 2013 Accepted 18 May 2013 Available online 27 May 2013 Keywords: Thermochemolysis Pyrolysis off-line Structural–activity ratio Beneficial microorganisms Diazotrophs Microbial survival a b s t r a c t 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 consti- tuted 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 con- tent 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 com- pared to cattle manure VC (approximately 10 4 times cells g -1 VC), 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 bacte- ria introduced to VC, which is a step toward understanding the relationship between the molecular characteristics of organic matter and the microbial activities. © 2013 Elsevier B.V. All rights reserved. 1. Introduction A large number of organic wastes can be ingested by earth- worms and excreted as vermicompost (VC), recycling nutrients and reducing environmental constraints [1]. This process acceler- ates organic residue stabilization, producing a greater proportion of hydrophobic organic matter, i.e., final stabilized organic prod- ucts enriched with humic acids [2] having high biological activities [3,4]. VC is the final product of organic wastes processed by earth- worms and can be used to alleviate soil contamination by heavy metals, PAHs and herbicides [5–7] due to its high chemical and biological activities. In another hand, there are a number of studies demonstrating the possibility of VC use as a vehicle for bioinocu- lants [8,9]. Microbiological processes such as biological nitrogen fixation, phosphate solubilization, and biostimulation can be ∗ Corresponding author. Tel.: +55 22 2739 7198. E-mail addresses: canellas@uenf.br, lucianocanellas@gmail.com (L.P. Canellas). improved with progressive knowledge about the relationship between the chemical nature of organic matter and the viabil- ity and activity of populations of natural or introduced beneficial microorganisms. Herbaspirillum seropedicae is an endophytic diazotrophic bac- terium that colonizes mainly graminaceous plants such as sugarcane, rice, wheat, sorghum, and maize [10]. Canellas et al. [11] showed that inoculation of maize with H. seropedicae in the presence of humic acids isolated from VC increased the bacterial population associated with the plant root as well maize grain yield. In another study under a technological perspective stressing the importance of organic matter in driving a microbial process, Busato et al. [12] inoculated VC from cattle manure with a mixture bacteria able to solubilize phosphate and fix atmospheric nitrogen, result- ing in increased phosphorus content for the agricultural substrate produced. However, in this study, the population of the introduced microorganisms decreased during VC maturation. A more effective plant growth medium using VC enriched with selected microor- ganisms depends on the maintenance of high levels of the selected 0165-2370/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jaap.2013.05.015