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Saccharopolyspora erythraea makes erythromycin, an antibiotic commonly used in human medicine. Unusually, the erythromycin biosynthetic (ery) cluster lacks a pathway-specific regulatory gene. We isolated a transcriptional regulator of the ery biosynthetic genes from S. erythraea and found that this protein appears to directly link morphological changes caused by impending starvation to the synthesis of a molecule that kills other bacteria, i.e., erythromycin. DNA binding assays, liquid and affinity chromatography, MALDI-MS analysis, and de novo sequencing identified this protein (Mr = 18 kDa) as the S. erythraea ortholog of BIdD, a key regulator of development in Streptomyces coelicolor. Recombinant S. erythraea BIdD bound to all five regions containing promoters in the ery cluster as well as to its own promoter, the latter with an order-of-magnitude stronger than to the ery promoters. Deletion of bldD in S. erythraea decreased the erythromycin titer in a liquid culture 7-fold and blocked differentiation on a solid medium. Moreover, an industrial strain of S. erythraea with a higher titer of erythromycin expressed more BIdD than a wild-type strain during erythromycin synthesis. Together, these results suggest that BIdD concurrently regulates the synthesis of erythromycin and morphological differentiation. The ery genes are the first direct targets of a BIdD ortholog to be identified that are positively regulated. cell differentiation | secondary metabolites | BIdD

There are many diverse strains of Geotrichum candidum in France, even within the same cheesemaking regions. This fungus colonizes many cheeses during the ripening process and contributes to the distinctive flavor and qualities of many different types of cheese.

Researchers describe an autocloning method that produces multiple copies of the gene for extracellular lipase in Yarrowia lipolytica. These strains could produce 40 times more lipase per liter than strains containing only one copy of the gene. This makes them a promising source of lipase for industrial use, waste treatment, and pancreatic insufficiency treatment.

Rhodococcus sp. N-774 is an industrially important microorganism used in the production of acrylamide by virtue of its strong nitrile hydratase (NHase) activity. To be able to further exploit these attributes, host-vector and transformation systems for Rhodococcus were developed. Two Escherichia coli-Rhodococcus shuttle vectors were developed. In addition, conditions for the efficient electroporation of plasmid DNA into Rhodococcus were determined. Using these systems, the NHase and amidase genes were successfully transferred and expressed in a new Rhodococcus host.

The construction of a 5.0-kilobase food-grade cloning vector for Streptococcus thermophilus is described. The vector construct carries DNAs from two different groups of food-approved bacteria incorporating a replicon from S. thermophilus and the cadmium resistance selectable marker from Lactococcus. Data show that the vector containing S. thermophilus can replicate in two industrial strains of the species.

Improved strains of Blakeslea trispora, obtained by mutation and heterokayosis yield higher content of beta-carotene and lycopene. Incubation of cells with the nicotine shifts the production from beta-carotene into lycopene. Data indicate that the highest production of beta-carotene and lycopene, 39 and 15 milligram per dry mass respectively, is seen in intersexual heterokaryons.

Improved strains of Blakeslea trspora by mutation and heterokaryosis yield higher content of beta-carotene than the wild-type and the production shifts to lycopene when the cells are incubated with nicotine. Data indicate that intersexual heterokayons yield the highest production, up to 39 milligram of carotene and 15 milligram of lycopene per gram dry mass.