Physiological and metabolic responses of microcystin-producer cyanobacterial strains to inorganic carbon

• Ano de defesa: 2022
• Autor(a) principal: Oder, Jean Coutinho
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Botânica
• Palavras-chave em Português: Cianobactéria - Crescimento; Cianobactéria - Metabolismo; Ecofisiologia Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/29643; https://doi.org/10.47328/ufvbbt.2022.320

The phylum Cyanobacteria (Bacteria domain) constitutes a group of gram-negative prokaryotes able to perform oxygenic photosynthesis. These organisms are widely distributed around the globe and can be found in free form or in symbiotic associations with plants, diatoms, fungi, and sponges. Cyanobacteria are very important for the biogeochemical cycles of carbon (C) and nitrogen (N), because they are able to fix inorganic C (Ci) and some genera also perform biological N fixation (BNF). Some cyanobacterial strains also produce toxins (cyanotoxins), such as microcystins (MCs), which have hepatotoxic effects in animals. In this study, we evaluated the effects of different Ci sources on the metabolism of two filamentous heterocytous MC-producer strains (Scytonemataceae CCM-UFV057 and Neowestiellopsis sp. CCM-UFV026), characterizing their growth and metabolic responses. For this, the two strains were grown separately in BG-11 0 medium, with 0.02 g·L -1 of sodium carbonate [control (C)]; and in BG-11 0 medium, with 0 g·L -1 (T1), 0.016 g·L -1 (T2), 0.032 g·L -1 (T3), 0.16 g·L -1 (T4), 0.8 g·L -1 (T5) and 1.6 g·L -1 of sodium bicarbonate (T6). The growth parameters of strain Neowestiellopsis sp. CCM-UFV026 were affected at T1 (0.016 g·L -1 of sodium bicarbonate), but were not affected as the Ci concentration increased. The strain Scytonemataceae CCM-UFV057 showed lower growth at T6 (1.6 g·L -1 of sodium bicarbonate). In the highest sodium bicarbonate concentration, both strains showed decreased pigment contents (chlorophyll a and phycobiliproteins). The strain Neowestiellopsis sp. CCM-UFV026 had its metabolism and growth rate less impacted at the higher Ci concentration than the strain Scytonemataceae CCM-UFV057, since the latter showed signs of chlorosis in its culture and high values of cellular glycogen. Keywords: Heterocitous strains. Growth rate. Growth curves. Metabolites contents.