Biology of termitomyces species and standardisation of its cultivation techniques

Abstract

State wide survey was conducted during the South West and North East monsoon periods in 1984-85 and nine species of Termitomyces were collected and identified from thirty two localities of the State. Among the nine specices, T. heimii, T. clypeatus and T. microcarpus var. Santalensis were the first record for Kerala. Detailed description of the morphological and microscopical characters of the nine species collected were recorded in the data sheet along with the ethiono mycological and gastronomic details. All termitomyces species were commonly consumed by the local people during the seasons and were known by different vernacular names. Observations on the periodicity frequency and intensity of occurrence of the nine species showed that T. microcarpus, T. microcarpus var. santalensis and T. robustus were the most commonly occurring species abundantly distributed throughout the State, irrespective of soil type. Their habit of occurrence also revealed that T. robustus and T. striatus were always seen solitary while all the other species occur gregariously consisting of ten to hundred sporocarps. The results relating to the periodicity of occurrence of different species of Termitomyces indicated a post monsoon maxima for the seven species belonging to subgenus Eutermitomyces and a monsoon maxima for the two species viz. T. microcarpus and T. microcarpus var. santalensis of the subgenus pratermitomyces. Studies conducted to observe the developmental morphology of T. robustus from mycelial stage till maturity revealed that different stages of development can be divided into eight stages viz. spherule, clove bud, primordial elongation, pseudorhizal stage, epigeal button, epigeal egg, epigeal elongation and mature stage. The first four stages of development were hypogeal and took 192 h to attain the 4th stage while the next four epigeal stages took only 96 h to reach the mature stage. Critical observations of the different stages of growth and development of the sporocarp revealed the significance of pseudorhiza and perforatorium in the hypogeal development of the sporocarp. The data relating to the temperature and humidity of the comb of T. clobulus and surrounding the environment showed insignificant variations. A comparative study of the chemical composition of the comb of T. robustus and T. heimii showed little difference in the total moisture content, cellulose, carbon, nitrogen and pH. Isolation of other fungi from the termitaria obtained from different localities revealed the occurrence of 19 species of fungi belonging to 12 genera indicating their possible role in cellulose decomposition in the environment. Among the nineteen species isolated, species of Aspergillus and xylaria were found to be the predominant fungi in the combs. Species belonging to Odontotermis was found to be the most common termite associated with different species of Termitomyces in Kerala. O. obesus was always found to be associated with its fungus mutualist Termitomyces microcarpus. The beetle Amblyopus cincetipinnis was found to be the common pest of Termitomyces. The beetle was found to interest and feed the emerging as well as mature sporocarps and turn them unfit for consumption. Field trials on the effect of soil moisture for the production of sporocarps revealed that the number of sporocarps emerged from the daily irrigated plots were more when compared to the non irrigated plots. Among the eight media tested Rebeeca’s selective medium was found to be the only medium to support scanty mycelial growth of T. robustus. Maximum mycelial growth was observed at 300C. Experiments on the effect of light in mycelial growth of T. robustus showed no significant differences in growth. In vitro studies indicated that cellulose was the best source of carbon followed by maltose and lactose. Maximum protein content was observed in T. heimii when compared to other species. Trials on the suitability of different substrates for spawn production failed to support any mycelial growth of the fungus. Dehydrated sporocarps preserved in sealed polythene covers showed maximum shelf life when compared to other ‘methods of preservation. Though fresh sporocarps could be stored in polythene bags for only 48 h it was possible to extend their shelf life when preserved in brine solution. Blanching and pickling and were the other method of preservation of the sporocarps of Termitomyces tried.