The sludge produced in wastewater treatment plants of slaughterhouses is a rich source of chemical, organic, and microbiological constituents that can be biotechnologically exploited. The purpose of this study was to (i) conduct a chemical analysis of the sludge, and (ii) isolate, quantify, and describe the amylolytic, cellulolytic, ligninolytic, proteolytic, and keratinolytic bacteria in the sludge. Sludge samples were collected at the wastewater treatment plant of the Francap SA poultry company. The nutrient contents, C/N ratio, and pH were determined. For the bacterial count, 10 g sludge was diluted in 90 mL saline solution, which was serially diluted to 10 -12 . Aliquots of 100 µL of each dilution were transferred to selective media for isolation of bacteria that degrade organic substances. The colony-forming units were determined for each culture medium. Individual colonies were purified and characterized morphologically. The sludge contained 9.5, 1.21, and 0.45 dag kg -1 of N, P, and K, respectively. Fiftytwo isolates were purified and characterized, with 2.11 × 10 12 to 9.55 ×10 15 colony-forming units per g sludge. In conclusion, the sludge generated in poultry slaughterhouse wastewater treatment plants is a rich source of organo-mineral constituents and bacteria with biotechnological potential for degrading organic substances. Key words: Agricultural microbiology. Organic matter. Solid waste. ResumoOs lodos produzidos nas estações de tratamento de efluentes de abatedouros são uma fonte de riqueza química, orgânica e microbiológica que precisa ser explorada biotecnologicamente. Objetivou-se neste estudo: (i) realizar a caracterização química do lodo e (ii) isolar, quantificar e caracterizar bactérias amilolíticas, celulolíticas, ligninolíticas, proteolíticas e queratinolíticas do lodo. Amostras de lodo foram coletadas na estação de tratamento de efluentes da empresa avícola FRANCAP S.A. Foram determinados os teores de nutrientes, a relação C/N e o pH. Para a quantificação bacteriana, 10 g de lodo foram diluídos em 90 mL de solução salina e dela, realizaram-se diluições seriadas até 10 -12 . Alíquotas de 100 µL de cada diluição foram transferidas aos meios seletivos para isolamento de bactérias degradadoras de substâncias orgânicas. Determinaram-se as unidades formadoras de colônia para cada meio de cultivo. Colônias individuais foram purificadas e caracterizadas morfologicamente. O lodo apresentou teores de N, P e K, de 9,5, 1,21 e 0,45 dag kg -1 , respectivamente. Foram purificados e caracterizados 52 isolados, as unidades formadoras de colônia variaram entre 2,11 x 10 12 a 9,55 x 10 15. Conclui-se que os lodos gerados nas estações de tratamento de efluentes de abatedouro de aves são uma fonte de riqueza organomineral, além de apresentar bactérias com potencial biotecnológico de degradar substâncias orgânicas. Palavras-chave: Matéria orgânica. Microbiologia agrícola. Resíduos sólidos.

Forest fires incorporate pyrogenic organic matter into the soil, affecting the characteristics of soil organic matter (SOM) due to its high aromaticity, increasing its renewal time. However, the factors that control the concentration of pyrogenic organic matter and its chemical composition and structure are still little known. Forest fragments dispersed in a savanna matrix of the northern Brazilian Amazon are frequently impacted by fires, which can affect the composition of SOM within the fragments. The aim of this study was to analyse the chemical composition of SOM in the border and interior of six forest fragments in the Roraima savanna, in the northern Brazilian Amazon. Soil samples were collected at 10-cm intervals up to 1 m in depth at the border and in the interior of each fragment. Soil organic material concentration was determined with 10% HF solution and its elemental composition, thermogravimetric index, and 13C CPMAS NMR spectroscopic analysis were determined. There was no significant difference in the aromaticity index between border and interior. The concentration of alkyl C structures between border (22 to 25%) and interior (19 to 29%) indicated the occurrence of medium-intensity fires in the study area. The thermogravimetric analysis showed no significant difference in the thermal stability of SOM between border and interior. Our results showed no pronounced difference in SOM quality up to 1 m depth between the border and the interior of the evaluated forest fragments, indicating that this compartment is stable throughout the fragments.

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The economic and environmental costs of nitrogen fertilization have intensified the search for technologies that reduce mineral fertilization, for example atmospheric nitrogen-fixing (diazotrophic) bacteria inoculation. In this context, the present study addressed the isolation and quantification of diazotrophic bacteria in the sludge from treated wastewater of a poultry slaughterhouse; a description of the bacteria, based on cell and colony morphology; and an assessment of growth and N content of maize plants in response to inoculation. Sixteen morphotypes of bacteria were isolated in six N-free culture media (JMV, JMVL, NFb, JNFb, LGI, and LGI-P). The bacteria stained gram-positive, with 10 rod- and six coccoid-shaped isolates. To evaluate the potential of bacteria to promote plant growth, maize seeds were inoculated. The experiment consisted of 17 treatments (control plus 16 bacterial isolates) and was carried out in a completely randomized design with six replicates. The experimental units consisted of one pot containing two maize plants in a greenhouse. Forty-five days after planting, the variables plant height, leaf number, stem diameter, root and shoot fresh and dry weight, and N content were measured. The highest values were obtained with isolate UFV L-162, which produced 0.68 g total dry matter per plant and increased N content to 22.14 mg/plant, representing increments of 74 and 133%, respectively, compared with the control. Diazotrophs inhabit sludge from treated wastewater of poultry slaughterhouses and can potentially be used to stimulate plant development and enrich inoculants.

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