An endophytic fungus, Gliocladium roseum (NRRL 50072), produced a series of volatile hydrocarbons and hydrocarbon derivatives on an oatmeal-based agar under microaerophilic conditions as analysed by solid-phase micro-extraction (SPME)-GC/MS. As an example, this organism produced an extensive series of the acetic acid esters of straight-chained alkanes including those of pentyl, hexyl, heptyl, octyl, sec-octyl and decyl alcohols. Other hydrocarbons were also produced by this organism, including undecane, 2,6-dimethyl; decane, 3,3,5-trimethyl; cyclohexene, 4-methyl; decane, 3,3,6-trimethyl; and undecane, 4,4-dimethyl. Volatile hydrocarbons were also produced on a cellulose-based medium, including heptane, octane, benzene, and some branched hydrocarbons. An extract of the host plant, Eucryphia cordifolia (ulmo), supported the growth and hydrocarbon production of this fungus. Quantification of volatile organic compounds, as measured by proton transfer mass spectrometry (PTR-MS), indicated a level of organic substances in the order of 80 p.p.m.v. (parts per million by volume) in the air space above the oatmeal agar medium in an 18 day old culture. Scaling the PTR-MS profile the acetic acid heptyl ester was quantified (at 500 p.p.b.v.) and subsequently the amount of each compound in the GC/MS profile could be estimated; all yielded a total value of about 4.0 p.p.m.v. The hydrocarbon profile of G. roseum contains a number of compounds normally associated with diesel fuel and so the volatiles of this fungus have been dubbed 'myco-diesel'. Extraction of liquid cultures of the fungus revealed the presence of numerous fatty acids and other lipids. All of these findings have implications in energy production and utilization.

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In the report, in order to determine which volatile compounds were produced by the fungus, the volatile organic compounds (VOCs) found in the GC-MS analyses of controls were removed from the list of VOCs appearing in the flask supporting fungal growth as done previously (Strobel et al., 2001). However, an examination of this approach has revealed that it was inaccurate for the study. The automated library search results generated from the NIST 2005 database spectral search were used as the only means of compound comparison between fungal products and those of the control. Due to the similarity of many alkane fragmentation patterns the automated search is not always reliable (Schulz & Dickschat, 2007). This difficulty in alkane identification was further complicated by a complex mixture of gases produced by NRRL 50072 that resulted in overlapping chromatographic peaks. The incomplete separation resulted in the automated library search algorithm (Agilent Chem Station Version C.0.0) returning different VOC assignments. This led to the incorrect conclusion that some compounds were in the fungal fermentation VOCs but not present in the controls. In addition to the automated library database search comparisons, manual inspection of retention times and fragmentation profiles for each chromatographic peak is necessary to accurately account for the mediaderived VOCs. The data reported in the revised tables (below) reflect changes made after these additional aspects of the GC-MS data analyses were considered and these represent the most conservative estimates of the fungal VOC production. The temperature programme used for GC was as follows: 40 u C for 2 min, 10 u C min 21 ramp to 230 u C final temperature and a 5 min hold at 230 u C. Therefore, as a result of these analytical difficulties, the VOCs in the tables in this Corrigendum primarily differ from those in the original paper by the absence of the branched-and long-chained alkanes. Since many of the VOCs made by this organism can serve as fuels or fuel additives, the term myco-diesel still applies, especially as it relates to the ability of this organism to produce a series of alkyl acetates, alcohols and acids representing some of the major straight-chained alkanes of diesel. Furthermore, the ability of the organism to digest cellulose and subsequently produce VOCs with fuel potential, while qualitatively different in the tables, is still notable. A more detailed and comprehensive study on the VOCs of this organism and a number of its close relatives is in this issue of Microbiology (Griffin et al., 2010). The overall conclusion is that the products of this organism following growth on a number of substrates have potential as fuels.

Oidium sp. has been recovered as an endophyte in Terminalia catappa (tropical chestnut) in Costa Rica. The volatile organic compounds (VOCs) of this organism uniquely and primarily consist of esters of propanoic acid, 2-methyl-, butanoic acid, 2-methyl-, and butanoic acid, 3-methyl-. The VOCs of Oidium sp. are slightly inhibitory to many plant pathogenic fungi. Previous work on the VOCs of Muscodor albus demonstrated that besides esters of small organic acids, a small organic acid and a naphthalene derivative were needed to obtain maximum antibiotic activity. Thus, the addition of exogenous volatile compounds such as isobutyric acid and naphthalene, 1,1'-oxybis caused a dramatic synergistic increase in the antibiotic activity of the VOCs of Oidium sp. against Pythium ultimum. In fact, at elevated concentrations, there was not only 100% inhibition of P. ultimum but killing as well. In addition, a coculture of Muscodor vitigenus (making only naphthalene) and Oidium sp. plus isobutyric acid produced an additive antibiosis effect against P. ultimum. The biological implications of multiple volatile compounds acting to bring about antibiosis in nature are discussed.