We have engineered Rhodosporidium toruloides to produce fatty alcohols by expressing a fatty acyl-CoA reductase from Marinobacter aquaeolei VT8. Production of fatty alcohols in flasks was achieved in different fermentation media at titers ranging from 0.2 to 2 g/L. In many of the conditions tested, more than 80 % of fatty alcohols were secreted into the cultivation broth. Through fed-batch fermentation in 7 L bioreactors, over 8 g/L of C16–C18 fatty alcohols were produced using sucrose as the substrate. This is the highest titer ever reported on microbial production of fatty alcohols to date.Electronic supplementary materialThe online version of this article (doi:10.1007/s10295-015-1674-x) contains supplementary material, which is available to authorized users.

Psychrotrophic bacteria isolated from raw milk were tested for their ability to adhere to steel, two types of rubber, and glass, materials employed in the construction of milking equipment. The adherence assays were carried out by exposure of the materials to radioactively labelled bacteria in both a buffering solution (Ringer's) and milk. The degree of adherence of Gram-positive bacteria was lower (P < 0-001) than that of Gram-negative bacteria. Glass was the material least prone to bacterial adherence (P < 0-001); there were no significant differences between the other three materials. Milk was found to inhibit adhesion significantly (P < 0-05), this inhibition being more evident with the most adherent bacteria. There was no statistically significant correlation between bacterial surface hydrophobicity and adherence. Our results suggest that intrinsic bacterial adherence cannot be considered a relevant factor in the contamination of milking equipment.

SummaryThe psychrotrophic bacterial flora of milk was examined after aseptic hand milking. A total of 409 strains were tentatively characterized and classified into 17 groups by a reduced set of tests and cluster analysis. Lipolytic organisms (53·7%) exceeded proteolytic organisms (29·6%), and a reported predominance of oxidase-positive organisms (54·5%) was not found. Gram-negatives were mainly Entero-bacteriaceae,Flavobacterium, AcinetobacterandPseudomonas. In the Gram-positive groups Micrococcaceae were the most abundant (44·4%) followed by coryneforms (16·3%). Only two of seven commonly used disinfectants acted differently with Gram-positive and Gram-negative organisms (P< 0·01), although in general Gram-positives were more resistant than Gram-negatives.

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