Fungal contamination associated with some dried fruits in Iran

In order to identify fungal species associated with some dried fruits including; Common fig, Date palm, and White Mulberry, 35 fruit samples were collected from common markets in the south of Kerman province, Jiroft, Iran, during 2016. After surface disinfestation with 0.5% NaOCl, small fragments of each dried fruit were plated onto Potato dextrose agar (PDA) medium. Recovered fungal isolates were purified by single spore method. Morphological characteristics of each isolate were recorded. Results of identification recorded that about seven fungal species including; Alternaria alternata , A. tenuissima , Arthrinium arundinis , Cladosporium cladosporioides , Clastospora gossypii var. polymorpha , Fusarium oxysporum and F. verticillioides were obtained. To the best of our knowledge, this is the first report of isolating and identifying the fungi associated with dried fruits in Iran.


Introduction
The wide range of temperatures and different climatic zones in Iran made the possibility to cultivate a diverse variety of crops. According to formal reports, more than 2000 plants were grown in this country. Agricultural products are very important in Iran especially for none-oil exports; in the meantime, dried fruits have the same important roles. Fungi are able to deteriorate food products and play important roles during their storage. So, it seems vital to conduct standard tests for checking fungal contamination of dried fruits and mycotoxins production. Many genera have been reported as contaminating fungi associated with dried fruits worldwide such as; Fusaria, Aspergilli, and Penicillium spp. (Srivastava et al., 2014;Tournas et al., 2015). Therefore, the present investigation aimed to isolate and identify fungal species associated with some dried fruits; collected from different common markets in some regions of Iran.

Sampling, Isolation and identification of fungi
Dried fruits tested in this study were collected from common markets in the south of Kerman province, Jiroft. Fungal isolation were carried out on  Ho and Ko, (1997). Single spore colonies were transferred into PDA, synthetic nutrient poor agar (SNA), and 2% malt-extract agar (MEA) media; and then incubated at 25°C under continuous fluorescent light to promote their sporulation. Preparations were mounted in lactic acid; and then studied under a CH2 Olympus microscope (x1000 magnification), equipped with a Sony Digital Camera. Measurements of 10 conidiophores and 30 conidia were taken in 50% lactic acid in reference to Amirmijani et al., (2014);(2015). Identification of each isolate was carried out using relevant literatures of Ellis, (1971), (1976Gerlach and Nirenberg, (1982); Leslie and Summerell, (2006);Simmons, (2007);Bensch et al., (2010), (2012).

Results and Discussion
49 fungal isolates were recovered on PDA plates including mainly eight fungal species that were identified as; Alternaria alternata, A. tenuissima, Arthrinium arundinis, Cladosporium cladosporioides, Clastospora gossypii var. polymorpha, Fusarium oxysporum, F. prolioferatum and F. verticillioides. All these fungi have been frequently reported from many substrates in Iran; but this is the first report of these fungi associated with dried fruits in this country. Moreover, C. gossypii var. polymorpha is a new record for Iranian Mycobiota. A brief description and illustrations of these 8 fungal species are presented. (Fries) Keissler, Beit, Bot. Central bl. 29: 433 (1912).
A. tenuissima is very similar to A. alternate; so it is difficult to identify and separate these species from each other by morphological data; however, there are some differences between them. One of the most important features for identifying these fungi was sporulation pattern. In A. tenuissima; conidia were produced in unbranched or less branched chains; whereas in A. alternata conidia were mostly produced in branched chains (Fig. 2.). Colonies were flat; spreading, with moderate aerial mycelium. On PDA; MEA and SNA media, surface of colony was iron-grey with patches of dirty white. Mycelium was smooth; hyaline, branched, and septate, of up to 3 µm in diameter. Conidiophores were reduced to conidiogenous cells, which were aggregated in clusters on hyphae. They were pale brown, smooth, sometimes ampulli form, (4-) 6-11 × 3-4 (-4.5) µm, had apical neck of 3-4 µm long; whereas, basal part was 4-6 µm long. Conidia were pale brown to brown; smooth and globose in surface view of (4-) 5-7 (-8) µm diameter, but were lenticular in side view of (3-) 4-4.5 µm diameter, with pale slit. This fungus was cosmopolitan; reported from tropical and temperate regions of Europe, Africa, Asia, North and South
After a week of incubation on PDA, colonies attained more than 8 cm in diameter. Purple or violet colonies; aerial mycelia were abundant, becoming felt like or floccose. This mycelium produced microconidia cohering in false head, never forming chains. Microconidia were 1 or 2 celled; cylindrical to ellipsoid, oval, straight to slightly curved or reniform. Macroconidia at first were solitarily scattered, and then become abundant on sporodochia. They were falcate; usually moderately curved, sub-cylindrical, with a pointed sometimes slightly hooked apical cell. They have mostly rather distinctly pedicellate basal cell; usually with 3 septa, 15−33 × 3.5−5 µm. Chlamydospores were abundant; terminal or intercalary, smooth or rough walled, globose to subglobose, single or in pairs. Conidiophores primarily formed were; short, single, lateral phialides on hyphae or loosely branched in the aerial mycelium. Later, they were formed in sporodochia that were densely irregular or verticillately branched. These conidiophores were monophialidic (Fig. 6). On PDA, F. oxysporum may be morphologically close to F. proliferatum, but it differs from this species by having false head and chlamydospores.
Novel Research in Microbiology Journal, 2018