Micro-organisms of stored leaves

Depending on the leaves (origin of plant material, handlings, phytosanitary status at harvest and during curing) and on the storage conditions (hygiene of premises, ambient humidity), numerous micro-organisms present on the lamina can grow on this normally dry substrate (figure 1).

Figure 1	Figure 2	Figure 3	Figure 4

Certain bacteria, such as Bacillus spp., Clostridium spp., Micrococcus spp., Streptomyces spp. or Acinetobacter calcoaceticus. Staphylococcus epidermidis are quite common on tobacco leaves. Note that we also isolated Staphylococcus xylosus from white deposits depreciating tobacco leaves for cigar wrappers. Note that these kind of deposits are frequently saline by nature.

Various moulds caused by different fungi can occur during leaf storage:
- Several species of Aspergillus (figure 2), such as Aspergillus fumigatus Fresen. (1863), Aspergillus flavus Link (1809), Aspergillus Niger var. Tieghi Niger. (1867), Aspergillus repens (Corda) Sacc. (1882), Aspergillus ruber Thom and Church (1926), Aspergillus ochraceus G. Wilh. (1877), Aspergillus versicolor (Vuill.) Tirab. (1908) and Eurotium Herbariorum (FH Wigg.) Link (1809) (formerly Aspergillus glaucus) (figure 3);
- Penicillium spp. (figure 4) such as Penicillium aurantiogriseum Dierckx (1901), Penicillium chrysogenum var. chrysogenum Thom (1910), Penicillium citrinumThom (1910), and Penicillium simplicissimum (Oudem.) Thom (1930);
- Many other fungi as well, such as Rhizomucor pusillus (Lindt) Schipper (1978), and Rhizopus spp. and Alternaria spp. Cunninghamella sp. Stemphylium sp. Epicoccum nigrum Link (1815), Chaetomium sp. Cladosporium herbarum (Pers.) Link (1816), Cladosporium cladosporioides (Fresen.) GA de Vries (1952), Scopulariopsis candida (Guég.) Vuille. (1911), Tsuda and Ueyama Pseudocochliobolus pallescens (1983), Geotrichum sp. Humicola insolens Cooney and R. Emera. (1964), Colletotrichum sp. Cochliobolus spicifera RR Nelson (1964) (formerly Helminthosporium spiciferum) Thermoascus aurantiacus Miehe (1907).

Note that some of these fungi have already been reported during the curing phase (see Parasitic problems).