Comment on: “Melanisation of Aspergillus terreus—Is Butyrolactone I Involved in the Regulation of Both DOPA and DHN Types of Pigments in Submerged Culture? Microorganisms 2017, 5, 22”

Abstract

A recent article by Palonen et al. describes the effect of butyrolactone I on the expression of a secondary metabolite biosynthesis gene cluster from Aspergillus terreus that shows similarities to fusarubin biosynthesis gene clusters from Fusarium species. The authors claim that two different types of pigments are formed in Aspergillus terreus conidia, whereby one pigment is termed a DOPA-type melanin and the second a DHN-type melanin. Unfortunately, the terminology of the classification of melanin-types requires revision as Asp-melanin present in A. terreus conidia is clearly distinct from DOPA-melanins. In addition, some hypotheses in this manuscript are based on questionable data published previously, resulting in incorrect conclusions. Finally, as biochemical data are lacking and metabolite production is only deduced from bioinformatics and transcriptomic data, the production of a second pigment type in A. terreus conidia appears highly speculative.

Lettuce (Lactuca sativa, variety Salanova) production in decoupled aquaponic systems: Same yield and similar quality as in conventional hydroponic systems but drastically reduced greenhouse gas emissions by saving inorganic fertilizer

“…Nevertheless, in all three treatments a classical growth pattern (lag-, log-, stationary- and death phase) was observed. Still the lag- and the stationary phase were not so pronounced in our experiments which could be explained by the weekly sampling intervals for CFU [50]. At the end of the experiment the CFU ranged between 502 (AP unt ) and 949 (AP dis ) in all treatments as it was similarly reported for sterilized and non-sterilized aquaponic lettuce production by Pantanella, Cardarelli [51].…”

Reply to the Comment on “Melanisation of Aspergillus terreus—Is Butyrolactone I Involved in the Regulation of Both DOPA and DHN Types of Pigments in Submerged Culture? Microorganisms 2017, 5, 22”

“…We can accept that the properties of the pgm gene cluster to produce pigment are unconfirmed by biochemical methods. As pointed out by Geib and Brock [ 3 ], the observed similarity with the fusarubin gene cluster of the Fusarium fujikuroi may indicate sexual development during the growth conditions used in this study. This raises a question regarding the observed upregulation of one of the key regulators of asexual conidiation, abaA —occurring exactly at the same time point as the pgm cluster genes are upregulated as well [ 5 , 6 ].…”

“…Regarding the several further thoughts presented by Geib and Brock [ 3 ], we agree on the necessity to confirm them with further studies. In our previous study [ 4 ], we observed an increase in lovastatin production, both on the transcriptional and molecular level, and showed it to be enhanced already 24 h after butyrolactone I supplementation, 96 h prior to the speculated pgm cluster genes showed upregulation as described in our current study [ 5 ].…”

“…However, the focus of our study was to characterise the revealed NR-PKS gene pgmA and the surrounding gene cluster on a transcriptional level by utilizing the obtained gene expression and transcriptome sequence data. We presented only a speculation regarding the function of this cluster as remarked in the comment presented by Geib and Brock [ 3 ].…”

“…Naturally, all these questions require further investigations as proposed by Geib and Brock [ 3 ]. Schimmel et al [ 8 ] reported butyrolactone I to increase the number of spores as well as lovastatin production.…”