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Cultured plant cells generally produce low levels of secondary metabolites, and elicitors of secondary metabolites usually inhibit callus growth. The aim of this study was to determine the effect of 5-aminolevulinic acid (ALA), a chlorophyll precursor that promotes plant growth, on callus induction from leaves of Taxus cuspidata, and on callus growth on solid medium. ALA at 0.76, 7.6, and 76 μM had similar effects on callus induction and growth, while ALA at 760 μM had negative effects. Next, the effects of ALA concentrations on callus growth and paclitaxel production in suspension cultures in the dark were evaluated. The results showed that 0.76 and 7.6 μM ALA stimulated growth and paclitaxel production, while 76 μM ALA had negative effects. ALA is thought to promote cellular activity under light conditions. Therefore, the effects of light intensity on callus growth and paclitaxel production in the presence of ALA were evaluated. Our results showed that the best conditions for callus growth and paclitaxel production were 7.6 μM ALA under photosynthetically active radiation of 12 μmol photons m−2 s−1. Callus growth and paclitaxel production were inhibited under stronger light (24 μmol photons m−2 s−1). Together, these results show that ALA promoted callus growth and the production of paclitaxel by light-grown cultured T. cuspidata cells.

We report here the development of a new bioreactor (bioreactor with foam separation, BFS) for efficient production and recovery of paclitaxel that circumvents paclitaxel's inhibitory effects on growth through a feedback mechanism. The BFS captures paclitaxel through its hydrophobic interaction with the foam generated by aerated culture medium. The BFS comprises co-axial 0.65 dm3 outer (150 mm height and 75 mm diameter) and 0.15 dm3 inner vessels (90 mm height and 50 mm diameter) equipped with a ball-type sparger (5–10 µm pore size, 10 mm diameter) and a wire-framed draft tube covered by a water-permeable cellulose bag (150 × 40 mm, 100 µm maximum pore size). The BFS was tested by adding paclitaxel alone to the medium of 0.12 dm3 in the inner vessel and collecting it in the foam that overflowed into the outer vessel. Paclitaxel was separated with first-order kinetics and was optimally recovered using an aeration rate of 0.05 dm3 min−1 (0.21 vvm). Next, a Taxus cuspidata callus was cultured using the optimal aeration rate. A conventional shaking culture (110 rpm) served as the control using a 0.2 dm3 Erlenmeyer flask (0.12 dm3 medium). Paclitaxel was maintained at less than 0.02 g m−3 in the inner vessel of the BFS. Consequently, there was no feedback inhibition, and the paclitaxel production increased by a factor of five in the BFS compared with the control culture where there was feedback inhibition by the high concentration of paclitaxel. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

Biochemical and radiographic abnormalities linked with phosphorus deficiency syndrome (PDS) developed in two very low birthweight (VLBW) infants fed exclusively with human milk. By increasing phosphorus (P) and calcium (Ca) intakes with the introduction of a specialized premature formula, osteopenia or rickets, as well as hypophosphatemia, hypo-phosphaturia and increased serum alkaline phosphatase levels improved in both patients. We speculated that all VLBW infants who are being fed exclusively with human milk should be monitored for PDS and that if PDS develops, supplementation of human milk with both P and Ca appears to be necessary for its treatment.