Quorum-Sensing Mechanisms Mediated by Farnesol in Ophiostoma piceae: Effect on Secretion of Sterol Esterase

Abstract

Ophiostoma piceae CECT 20416 is a dimorphic wood-staining fungus able to produce an extracellular sterol-esterase/lipase (OPE) that is of great biotechnological interest. In this work, we have studied the morphological change of this fungus from yeast to hyphae, which is associated with the cell density-related mechanism known as quorum sensing (QS), and how this affects the secretion of OPE. The data presented here confirm that the molecule E,E-farnesol accumulates as the cell number is growing within the population. The exogenous addition of this molecule or spent medium to the cultures increased the extracellular activity of OPE 2.5 times. This fact was related not to an increase in microbial biomass or in the expression of the gene coding for OPE but to a marked morphological transition in the cultures. Moreover, the morphological transition also occurred when a high cell density was inoculated into the medium. The results suggest that E,E-farnesol regulates through QS mechanisms the morphological transition in the dimorphic fungus O. piceae and that it is associated with a higher extracellular esterase activity. Furthermore, identification and transcriptional analysis of genes tup1 and cyr1, which are involved in the response, was carried out. Here we report enhanced production of a sterol-esterase/lipase of biotechnological interest by means of QS mechanisms. These results may be useful in increasing the production of secreted enzymes of other dimorphic fungi of biotechnological interest.T riacylglycerol esterases, also known as lipases, have acylglycerols as their natural substrates, while sterol esterases hydrolyze fatty acid esters of sterols. In addition, both kinds of enzymes are able to carry out synthesis reactions in the presence of organic solvents (1, 2). They are widespread in nature, but those from microorganisms, especially fungi, have gained special interest due to their broad substrate specificity and their potential application for biotechnological applications (2).Ophiostoma piceae is a wood-staining fungus and is a causal agent of pine and spruce discoloration. Although it is not a pathogenic species and associates with nonaggressive bark beetles, the infection results in substantial economic losses in the forestry industry (3). Its ability to produce a morphological transition from yeast to hyphal forms, depending on fungal culture conditions, probably contributes to its adaptation to different environmental conditions (3). The effect of inoculum size on culture morphology of fungi from the genera Ophiostoma has been recently reported, suggesting that yeast-or hypha-like growth could be associated with quorum-sensing (QS) activity (4).The fungus O. piceae CECT 20416 produces an extracellular sterol esterase (OPE) with activity on triglycerides, esters of p-nitrophenol, and cholesterol (5). This is the only esterase secreted by this strain, and it represents a major protein in the crude enzyme obtained using a basal medium supplemented with olive oil. The enzyme is a glycosylated protein,...

Essential Oils and Microbial Communication

“…Furthermore, oxylipins regulate a QS-dependent pathway controlling development and mycotoxin production [34]. Fungi produce also other QSMs: terpenes, such as farnesol, are produced, for instance, by the dimorphic fungi C. albicans [28] and Ophiostoma piceae [35]; cyclic sesquiterpenes act as QSMs for the dimorphic fungus Ophiostoma floccosum [36]; QS alcohols, including tryptophol and phenylethyl alcohol, are produced by S. cerevisiae [21]. It is important to underline that the higher organisms evolved mechanisms with which they are capable to interfere with the quorum sensing process of the bacteria.…”

From yeast to hypha: defining transcriptomic signatures of the morphological switch in the dimorphic fungal pathogen Ophiostoma novo-ulmi

“…Inoculum size is also implicated in the regulation of the Y-to-H transition in DED fungi and effects have been confirmed for O. ulmi , both subspecies of O. novo-ulmi ( americana and novo-ulmi ), and O. himal-ulmi [8, 14–16]. Moreover, quorum sensing has been shown in O. ulmi, O. piceae and O. floccosum [15, 17, 18]. Until now, only two genes have been identified as being involved in the dimorphism in O. novo-ulmi , namely COL1 [19] and an as yet uncharacterized gene that also affects asexual sporulation (synnematospores) and pathogenicity [20, 21].…”

Farnesol-induced hyperbranched morphology with short hyphae and bulbous tips of Coriolus versicolor

“…Similar phenomenon was also reported in O . piceae and Penicillium decumbens treated with farnesol 7 , 34 . Fig.…”

“…niger and Ustilago maydis 13 , 30 , tup1 and hog1 in Ophiostoma piceae and C . albicans 7 , 8 , were identified in the publicly available genomes of C . versicolor FP-101664 31 .…”

“…Several studies have suggested that quorum sensing molecule (QSM) can induce complex cellular behavior including morphological switches and secretion of extracellular enzymes 7 – 9 . Farnesol as the first QSM in fungi is well characterized in Candida albicans where farnesol blocks the yeast-to-mycelium shift 10 .…”