Prevalence of keratinophilic fungi in usar soils of Uttar Pradesh , India

Alkaline soils commonly called as Usar soil having pH 7.5 to 11.0 is commonly found in regions having poor drainage and little percolation. These soils occupy vast tracts of barren lands in the northern parts of India. These areas are frequently visited by man and animals, however there are no reports on the occurrence of keratinophilic fungi from the Usar soils. The purpose of this research was to study the occurrence of keratinophilic fungi in the alkaline Usar soil. To investigate the occurrence of soil keratinophilic fungi from Usar soil, 120 samples were collected from five districts of Uttar Pradesh viz. Lucknow, Bareilly, Azamgarh, Balia and Pratapgarh. Keratinophilic fungi were isolated by the hair baiting techniques using human hair as keratin bait. The cultures were identified using macroand micro morphological features. Eighty-tow strains of keratinophilic fungi were recovered from 120 (68.33%) soil samples. The isolated fungi were composed of ten species of five genera viz. Chrysosporium indicum (19.16%), Microsporum gypseum (12.5%), Chrysosporium tropicum (10.0%), Chrysosporium pannicola (7.5%), Trichophyton terrestre (5.83%), Chrysosporium lucknowense (4.16%), Chrysosporium state of Ctenomyces serratus (3.33%), Gymnascella dankailensis (3.33%), Gymnoascus reessii (1.66 %) and Trichophyton mentagrophytes (1.66 %). The presence of keratinophilic fungi in the Usar soils of Uttar Pradesh, India indicates that these fungi do occur at higher alkalinity.


Introduction
Alkaline soils commonly termed as Usar soil occupy vast tracts of barren lands in India.Such soils are commonly found in regions having poor drainage and little percolation.The pH of such soil ranges from 7.5 to 11.0 and it is mostly white alkaline type.The salts generally present in these soils are the carbonates, bicarbonates, sulphate and chlorides of calcium and magnesium.The carbonates and bicarbonates of sodium are present in large quanti-ties than the sulphates and chlorides.Thus the free exchangeable sodium ions make these soils highly alkaline and thus raise pH considerably.Such soils have either no vegetation at all or have patches of poor grass growth, interspread with areas which shows prominent whitish salt excrescences.The soil being devoid of vegetation coupled with low moisture content is subjected to high temperature, drought and intense solar radiations for greater part of the year which makes it an interesting habitat for such study.2][3] However, we have not found the reports on the occurrence of keratinophilic fungi from these alkaline soils, although these areas are frequently visited by man and animals.Therefore the present work was conducted to study the occurrence of keratinophilic fungi from Usar soil from five districts of Uttar Pradesh, India.

Materials and Methods
One hundred and twenty soil samples were collected from five sites of Usar soils in five districts of Uttar Pradesh viz.Lucknow, Bareilly, Azamgarh, Balia and Pratapgarh during March 2009 to February 2010 (Table 1).The samples were collected from the superficial layer of soil at a depth not exceeding 3-5 cm with a plastic spoon in sterile polyethylene bags, brought to the laboratory and stored at 15°C for a maximum of two weeks if not processed promptly.
Keratinophilic fungi were isolated by the hair baiting technique of Vanbreuseghem 4 using human hair as keratin bait.For this purpose, sterile Petri dishes half filled with the soil samples and moistened with sterile water were baited by burying sterile human hair in the soil.These dishes were incubated at room temperature (28±1°C) and examined daily from the fifth day for fungal growth over a period of four weeks.After observing the growth under a stereoscopic binocular microscope, isolates were cultured on Sabouraud's dextrose agar supplemented with chloramphenicol (50 mg/L) and cycloheximide (500 mg/L).
These fungi were identified based on the monographs of Sigler and Carmichael, 5 Oorchschot, 6 Currah, 7 von Arx, 8 Cano and Guarro 9 using macro-and micro morphological features.
Chrysosporium indicum was the most dominant fungal species isolated from Usar soils.It was reported from Indian soils by various workers [10][11][12] and dominates the mycobiota of the Indian soils because it is adapted to warmer conditions of India. 10icrosporum gypseum (12.5%) was the next most frequent isolate followed by cosmopolitan Chrysosporium tropicum (10.0%).Microsporum gypseum is a geophilic dermatophyte, universal in soil and has been encountered in one or more countries of each continent. 13It causes ringworm of the scalp and glabrous skin in human beings. 146][17] Chrysosporium tropicum is reported from various parts of India. 10,15,18hrysosporium pannicola was 7.5% in distribution and was reported from Indian soils as Trichophyton evolceanui by Randhawa and Sandhu, 16 then Garg 10 placed it in the genus Chrysosporium as C. evolceanui.While revising the genus Chrysosporium, Oorchschot 6 placed it as C. pannicola.It is reported from Indian soils.10,16,[19][20] Regarding other dermatophytes, we encountered Trichophyton mentagrophytes and T. terrestre which were recovered from 1.66% and 5.83% soil samples respectively.Trichophyton mentagrophytes has been reported from Indian soils 10,11,15,16,19,21 and is known to cause diseases in man and animals.[24][25][26][27] The other species isolated were Chrysosporium lucknowense (4.16%), Chrysosporium state of Ctenomyces serratus (3.33%), Gymnascella dankailensis (3.33%), and G. reessii (1.66%). Chysosporium state of Ctenomyces serratus was reported from Indian soils by various workers.16,19,28 Gymnoascus reessii was reported by Deshmukh [21][22] and Ghosh and Bhatt 29 and G. dankailensis by Verekar and Deshmukh 20 from Indian soils.Chrysosporium lucknowense was first time reported from Lucknow by Garg 10 followed by Deshmukh and Shukla, 30 Nigam and Kushawaha, 31 Dixit and Kushwaha, 32 Saxena et al. 33 Species of Chrysosporium are known to cause diseases in man and animals.34- 37 .Similarly species of Gymnascella i.e. G hyalinospora causes the infection in human being.38 Thus, these fungi may be regarded as opportunistic pathogens.
Aphanoascus durus, Aphanoascus punsolae, Auxarthron kuehnii, Chrysosporium indicum, Chrysosporium tropicum, Chrysosporium sp., Chrysosporium state of Ctenomyces serratus were reported from the vicinity of meteorite crater soils of Lonar (India). 39The lake water is alkaline, having an average pH of 10.5-11.2 and temperature of 35°C.Salts and minerals like sodium, chloride, carbonates, fluorides and bicarbonates are found in the lake.Alkalinity of the lake is attributed to the high content of sodium carbonate. 40ecently Jain and Sharma 41  A perusal of the Table 2 indicates that these fungi preferred neutral to alkaline soil.The  Trichophyton terrestre, Microsporum gypseum and Chrysosporium indicum were recorded at pH 9 and above.This indicates that these fungi are able to survive as resting spore in the soil under pH 9 or above and germinate when suitable condition arises.Thus, the results of this study points to an influence of the alkaline pH (7.5-9.00) on the growth of most of the keratinophilic fungi.3][44] However, the growth of some keratinophilic fungi in acid pH was also observed in other studies. 45

Conclusions
In our study it can be concluded that keratinophilic fungi occurs in the Usar soils of Uttar Pradesh and are surviving in harsh conditions like high pH and radiation.
These fungi may be playing an important role in decomposing the keratinic mater added to these uncultivated lands on one hand and may be a source of infection to the people visiting these areas.Garg 10 also emphasized that the climate and perhaps other environmental factors are apparently important in determining the distribution of keratinophilic fungi.
maximum numbers of fungi were recorded in the range of pH 7.5 to 8.5.Only few fungi viz.