Characterisation of the fungal population in citrus packing houses

The aim of this work was the characterisation of the environmental and superficial mycoflora of equipment and facilities of two citrus packing houses in Sao Paulo State, Brazil, in 2004 and 2005. One of the packing houses packed fruit for the export market (municipality of Matao), the other for the domestic market (municipality of Engenheiro Coelho). The study also identified the presence of isolates of Penicillium spp. resistant to thiabendazole and imazalil fungicides in packing houses. The environmental mycoflora was sampled according to the gravimetric method, using Petri dishes containing potato dextrose agar medium opened for 2 min. The superficial mycoflora on equipment and facilities was sampled with Rodac plates. The mycoflora in the environment and on surfaces of the packing houses in Matao were 12.3 and 52.3 cfu/plate, respectively, while these populations for the Engenheiro Coelho packing house were 46.3 and 68.2 cfu/plate, respectively. Cladosporium and Penicillium were the most prevalent genera of fungi. The contamination levels of clean zones in the packing houses (washing of fruits, packing table, boxes and containers) was not substantially lower than the contamination in dirty zones (reception of fruits and first selection). The percentage of P. digitatum isolates in Matao that was resistant to thiabendazole and imazalil was 25.9 and 1.5 in the environment and 30.1 and 16.0 on packing house surfaces, respectively. In Engenheiro Coelho, percentage of resistance to these fungicides was 51.9 and 0.1 in the environment and 39.2 and 0.9 on packing house surfaces, respectively.