Submitted by Regina Correa (rehecorrea@gmail.com) on 2016-09-21T20:04:08Z No. of bitstreams: 1 DissVG.pdf: 887031 bytes, checksum: 3c091b1ab0f608725eb27c6b2e22b2d5 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-23T18:38:21Z (GMT) No. of bitstreams: 1 DissVG.pdf: 887031 bytes, checksum: 3c091b1ab0f608725eb27c6b2e22b2d5 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-23T18:38:29Z (GMT) No. of bitstreams: 1 DissVG.pdf: 887031 bytes, checksum: 3c091b1ab0f608725eb27c6b2e22b2d5 (MD5) / Made available in DSpace on 2016-09-23T18:38:36Z (GMT). No. of bitstreams: 1 DissVG.pdf: 887031 bytes, checksum: 3c091b1ab0f608725eb27c6b2e22b2d5 (MD5) Previous issue date: 2015-12-14 / Não recebi financiamento / The microbial community plays an essential role in maintaining the ecological balance of soil. Interactions between microorganisms and plants have a major influence on the nutrition and health of the latter, and growth-promoting rhizobacteria can be used to improve plant development through a wide range of mechanisms. Therefore, the objective of the present study was to evaluate bacteria as biological control agents to Phytophthora nicotianae and as growthpromoting agents for citrus rootstocks. Altogether were evaluated 30 bacterial isolates, 11 Bacillus spp., 11 actinobacteria, and 8 lactic acid bacteria. For P. nicotianae control tests at first was performed an bioassay with alfalfa seedling in order to select the most promising bacterial isolates for the biocontrol and, posteriorly, the best isolates were applied in Sunki mandarin (Citrus sunki Hort. ex Tan), and rangpur (Citrus × limonia Osbeck) by seeds and substrate microbiolization methods. It was evaluated the number of surviving plants, at 90 days after sowing and inoculation. The same Isolates also were evaluated in vitro for indoleacetic acid production, phosphate solubilization, and nitrogen (N) fixation. In vivo testing consisted of growth promotion trials of the bacterial isolates that yielded the best results on in vitro tests with three rootstocks: Swingle citrumelo [Citrus × paradisi Macfad cv. Duncan × Poncirus trifoliata (L.) Raf.], Sunki mandarin and rangpur. The parameters of interest were height, number of leaves, stem diameter, shoot and root dry mass, and total dry mass at 150 days after germination. The results showed that alfalfa seedling bioassay vi was able to evaluate the potential for biocontrol of bacterial isolates against to P. nicotianae, BL06 and BL12 (both lactic acid bacteria) showed potential to be used as biocontrol agents of disease, independently from the application method. BM16 and CPMO4 were able to promote growth of Swingle citrumelo. In Sunki mandarin plants, the best treatment results were obtained with BM17 (Bacillus sp.) and ACT11 (actinobacteria). For Rangpur lime rootstock, only BM05 (Bacillus sp.) was able to promote increase in two parameters assessed, height and number of leaves. / A comunidade microbiana tem um papel fundamental na manutenção do equilíbrio ecológico do solo. As interações entre micro-organismos e plantas têm grandes influencias sobre a sanidade e a nutrição das mesmas, nesse contexto, o uso de rizobactérias promotoras de crescimento pode melhorar o desenvolvimento das plantas, por meio de uma ampla variedade de mecanismos. Portanto, o presente trabalho teve como objetivo avaliar bactérias como agentes de controle biológico de Phytophthora nicotianae e como promotoras de crescimento de porta-enxertos de citros. Ao todo foram avaliados 30 isolados bacterianos, sendo 11 Bacillus spp., 11 actinobacterias e 8 bactérias láticas. Para os ensaios de controle de P. nicotianae, incialmente, foram realizados ensaios com brotos de alfafa com a finalidade de selecionar os isolados bacterianos mais promissores para o biocontrole e, posteriormente, os melhores isolados foram aplicados em plantas de tangerina Sunki (Citrus sunki Hort. ex Tan) e limão Cravo (Citrus limonia Osbeck) pelos métodos de microbiolização das sementes e microbiolização do substrato, avaliando-se o número de plantas sobreviventes 90 dias após a semeadura e inoculação. Os 30 isolados bacterianos foram, também, avaliados in vitro quanto à produção de ácido indolacético, solubilização de fosfato e fixação de nitrogênio. Em seguida, para estudo da promoção de crescimento de plantas cítricas, foram realizados testes in vivo utilizando três porta-enxertos, citrumelo Swingle [Citrus paradisi Macfad cv. Duncan x Poncirus trifoliata (L.) Raf.], tangerina Sunki e limão Cravo, sendo utilizados como parâmetros de avaliação, a altura, o número de folhas, o diâmetro do caule, a massa seca da raiz, a massa seca da iv parte aérea e a massa seca total. Pelos resultados obtidos verificou-se que o ensaio realizado com brotos de alfafa permitiu avaliar o potencial de biocontrole das bactérias testadas contra P. nicotianae; os isolados de bactéria lática BL06 e BL12 apresentam potencial para serem utilizados como agentes de biocontrole da doença, independente do método de aplicação utilizado; os isolados de Bacillus spp. BM16 e CPMO4 foram capazes de promover o crescimento do porta-enxerto Citrumelo Swingle, enquanto que, BM17 (Bacillus sp.) e ACT11 (actinobacteria) promoveram o crescimento de plantas de tangerina Sunki. Para o porta-enxerto limão Cravo, apenas BM05 (Bacillus sp.) foi capaz de promover aumento da altura e do número de folhas das plantas.

ABSTRACT Anaerobic digestion is one way of handling biowaste and generating energy in the form of methane, biogas. This study shows that spore forming bacterias survive the process of pasteurisation and anaerobic digestion in biogas plants. It has also been established that both the nonpasteurised-and digestion- waste contains pathogen spore forming bacterias. Two Swedish full-scale commercial biogas plants were sampled before pasteurisation, after pasteurisation and after digestion on 10 occasions with one week intervals. The samples were analysed quantitatively and qualitatively, with biochemical methods, for Clostridium spp and Bacillus spp. Polymerase Chain Reaction, a biomolecular method, was used for C. chauvei analysis, with C. chauvei specific primers. For this analyse the biogas plants were sampled at 11 occasions. Survival of pathogenic spore forming bacteria in digestion residue may be a health risk for both humans and animals. The digested residue may be used as fertiliser on arable land and the risk of contamination by pathogenic Clostridium spp and Bacillus spp is hard to assess, but can not be neglected.