Allelopathy of the eucalypt has been considered as an important mechanism for the biodiversity reduction in the eucalypt plantation. To understand the allelopathic potential of the eucalypt (Eucalyptus grandis) roots and rhizosphere soil along a chronosequence (2, 4, 6, 8, 10 years), the germination and growth characteristics of three plant species (Raphanus sativus, Phaseolus aureus, and Lolium perenne) growing nearby or beneath the eucalypt plantations were measured. The results showed that aqueous extract of E. grandis root suppressed the germination and early seedling growth of the target plants. The younger E. grandis exhibited a comparatively stronger allelopathic potential. The highest dose root extracts from 4 years old E. grandis showed the strongest inhibitory effects on the germination rates of the target species, the inhibitory rates were about 48, 51.2, and 56.56% for R. sativus, P. aureus, and L. perenne, respectively. However, present biotests of rhizosphere soils from 6, 8, and 10-year-old plantations exhibited a remarkable stimulative effect on L. perenne, which indicated that the soil might neutralize or dilute allelopathic agents with the increase of plantation age. In addition, according to GC-MS analysis, more allelopathic potential compounds were found in the rhizosphere soil and roots of younger E. grandis plantation. Moreover, more allelochemicals were obtained from soil than from roots. The allelopathic compounds in roots and rhizosphere soil may play important roles in allelopathy of E. grandis plantation. More attention should be paid to the younger E. grandis plantations for the relative higher allelopathic effects.

The pharmacological importance of recombinant human stem cell factor (rhSCF) has increased the demand to establish effective and large-scale production and purification processes. A good source of bioactive recombinant protein with capability of being scaled-up without losing activity has always been a challenge. The objectives of the study were the rapid and efficient pilot-scale expression and purification of rhSCF. The gene encoding stem cell factor (SCF) was cloned into pBV220 and transformed into Escherichia coli. The recombinant SCF was expressed and isolated using a procedure consisting of isolation of inclusion bodies (IBs), denaturation, and refolding followed by chromatographic steps toward purification. The yield of rhSCF reached 835.6 g/20 L, and the expression levels of rhSCF were about 33.9% of the total E. coli protein content. rhSCF was purified by isolation of IBs, denaturation, and refolding, followed by SP-Sepharose chromatography, Source 30 reversed-phase chromatography, and Q-Sepharose chromatography. This procedure was developed to isolate 5.5 g of rhSCF (99.5% purity) with specific activity at 0.96 × 10 IU/mg, endotoxin levels of pyrogen at 1.0 EU/mg, and bacterial DNA at 10 ng/mg. Pilot-scale fermentations and purifications were set up for the production of rhSCF that can be upscaled for industry.