Microbial Community Changes Elicited by Exposure to Cyanobacterial Allelochemicals

Abstract

An increasing body of evidence points out that allelopathy may be an important process shaping microbial communities in aquatic ecosystems. Cyanobacteria have well-documented allelopathic properties, mainly derived from the evaluation of the activity of allelopathic extracts or pure compounds towards monocultures of selected target microorganisms. Consequently, little is known regarding the community dynamics of microorganisms associated with allelopathic interactions. In this laboratory-based study, a Microcystis spp.-dominated microbial community from a freshwater lake was exposed, for 15 days, to exudates from the cyanobacterium Oscillatoria sp. strain LEGE 05292 in laboratory conditions. This cyanobacterium is known to produce the allelochemicals portoamides, which were among the exuded compounds. The community composition was followed (by means of polymerase chain reaction followed by denaturing gradient gel electrophoresis and microscopic analyses) and compared to that of a non-exposed situation. Following exposure, clear differences in the community structure were observed, in particular for cyanobacteria and unicellular eukaryotic taxa. Interestingly, distinct Microcystis genotypes present in the community were differentially impacted by the exposure, highlighting the fine-scale dynamics elicited by the exudates. These results support a role for cyanobacterial allelochemicals in the structuring of aquatic microbial communities.

Dietary input of microbes and host genetic variation shape among-population differences in stickleback gut microbiota

“…Second, food intake and digestion rates affect the speed of food passage through the gut and thus the rate at which microbes are lost via excretion. Third, colonist persistence depends on interactions with other microbes , including resource competition (Mahowald et al, 2009), allelopathy (Leão et al, 2012) and cross-feeding (Rey et al, 2010). Fourth, colonizing microbes must survive potential host immune responses (Gomez and Balcazar, 2008;Maslowski and Mackay, 2011;Round et al, 2011;Carvaho et al, 2012;Hooper et al, 2012;Biswas and Kobayashi, 2013;Cebula et al, 2013;Robertson and Girardin, 2013;Bolnick et al, 2014b).…”

Sensitivity of salad greens (Lactuca sativa L. and Eruca sativa Mill.) exposed to crude extracts of toxic and non-toxic cyanobacteria

“…There is evidence of several of these effects in the aquatic community. For example, Leão et al (2012) demonstrated, in a laboratory study, that substances produced by the LEGE 05292 strain of Oscillatoria sp. (portoamides A, B, C and D) had inhibitory effects on the growth of species of cyanobacteria, diatoms and green algae.…”

“…Furthermore, the toxin interferes with the metabolism of the seedlings (Saqrane et al, 2009), causing necroses (Chen et al, 2004, M-Hamvas et al, 2003. However, it should be noted that cyanobacteria produce several compounds other than cyanotoxins (Leão et al, 2012), the function of which is still unknown, as are their effects on plants. Although on aquatic community some organisms may suffer direct effects due to contact with these different compounds (Leão et al, 2012).…”

“…However, it should be noted that cyanobacteria produce several compounds other than cyanotoxins (Leão et al, 2012), the function of which is still unknown, as are their effects on plants. Although on aquatic community some organisms may suffer direct effects due to contact with these different compounds (Leão et al, 2012). Thus, our objective was to compare the effect of crude extract from a strain of microcystin-producing M. aeruginosa (MC+) and non-microcystin-producing M. aeruginosa (MC-) on seed germination and seedling development of lettuce (Lactuca sativa L.) and arugula (Eruca sativa Mill.…”

Análise genômica e funcional da cianobactéria Nostoc sp. CENA67 e caracterização da sua comunidade microbiana associada

“…Algumas cianobactérias aparentam de fato possuir certa influência sobre a composição taxonômica de suas comunidades associadas, exercitando controle através de mecanismos de competição e de facilitação, como a liberação de carbono e nitrogênio fixados (BRAUER et al, 2015). Além disso, metabólitos secundários de efeito alelopático, incluindo inibidores de protease e bacteriocinas, podem ser liberados por diversas cianobactérias e essas moléculas poderiam, portanto, impactar a comunidade e atuar como agentes de seleção de micro-organismos (LEÃO et al, 2012b;SILVA-STENICO et al, 2011;SIVONEN, 2011 Interações entre cianobactérias e heterótrofos em consórcios, apesar de específicas a cada produtor primário, geralmente têm como padrão a troca mutualista de oxigênio e carbono, liberados pelas células cianobacterianas, por metabólitos produzidos por células heterotróficas, como nutrientes e vitaminas (COLE et al, 2014). Algumas análises transcritômicas fornecem suporte a essa observação, e também indicam que uma situação semelhante pode ser observada em relação ao nitrogênio fixado por cianobactérias diazotróficas em cocultivo com bactérias heterotróficas (BELIAEV et al, 2014).…”