Aspergillus niger is an opportunistic human pathogen and a strong air pollutant. A study was conducted with 75 different essential oils for the inhibition of hyphal growth and spore formation in Aspergillus niger. Cinnamomum zeylanicum (bark), Cinnamomum zeylanicum (leaf), Cinnamomum cassia, Syzygium aromaticum and Cymbopogon citratus were the top five essential oils which demonstrated marked inhibitory effect against hyphal growth and spore formation of A. niger. The chemical composition of these five most active essential oils was investigated by gas chromatography-mass spectra (GC-MS). Most of the other essential oils were found challenging to combat A. niger, suggesting their use as strong aroma therapeutic agents.

The anti-Fusarium oxysporum f. sp cicer (FOC) and anti-Alternaria porri (A. porri) effects were evaluated for 75 different essential oils. The most active essential oils found were those of lemongrass, clove, cinnamon bark, cinnamon leaf, cassia, fennel, basil and evening primrose. However, the effectiveness of these essential oils with both the tested fungi showed different responses. The level of inhibition was compared with Hexaconazole. GC-MS analysis for five oils amongst the 75 essential oils tested was performed. The potential of these essential oils as an ecofriendly and economic approach as a fungicide for FOC and A. porri is discussed.

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A novel method of growing calcium tartrate single crystals was developed in which the crystals were hanging freely in solution assisted by fine filaments of fungi (Aspergillus niger). Spores of A. niger were inoculated and allowed to grow in the supernatant solution of calcium chloride and tartaric acid (1:1) on the silica hydrogel impregnated with orthophosphoric acid. Transparent, prismatic, calcium tartrate crystals were grown hanging in the filamentous network of the fungi after 10 days in the supernatant solution. This network of the mycelium facilitated and mimicked the gel. The grown crystals were identified as calcium tartrate trihydrate and characterized by powder XRD, FTIR and TGA. This technique provides an alternate and a novel technique to grow crystals.

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