Vasundhara_2024_Arch.Microbiol_206_264

Fungi that inhabit fire-prone forests have to be adapted to harsh conditions and fungi affiliated to Ascomycota recovered from foliar litter samples were used for bioprospecting of molecules such as enzymes. Agni's fungi isolated from leaf litter, whose spores are capable of tolerating 110 (o)C were screened for thermostable lipases. One of the isolates, Leptosphaerulina trifolii A SMR-2011 exhibited high positive lipase activity than other isolates while screening through agar plate assay using Tween 20 in the medium. Maximum lipase activity (173.2 U/mg) of L. trifolii was observed at six days of inoculation and decreased thereafter. Among different oils used, the maximum lipase activity was attained by soybean oil (940.1 U/mg) followed by sunflower oil (917.1 U/mg), and then by mustard oil (884.8 U/mg), showing its specificity towards unsaturated fatty acids. Among the various organic nitrogen sources tested, soybean meal showed maximum lipase activity (985.4 U/mg). The partially purified enzyme was active over a wide range of pH from 8 to 12 with a pH optimum of 11.0 (728.1 U/mg) and a temperature range of 60-80 (o)C with an optimal temperature of 70 (o)C (779.1 U/mg). The results showed that lipase produced by L. trifolii is alkali stable and retained 85% of its activity at pH 11.0. This enzyme also showed high thermal stability retaining more than 50% of activity when incubated at 60 (o)C to 90 degreesC for 2 h. The ions Ca(2+) and Mn(2+) induced the lipase activity, while Cu(2+) and Zn(2+) ions lowered the activity compared to control. These results suggests that the leaf litter fungus L. trifolii serves as a potential source for the production of alkali-tolerant and thermostable lipase.