The selection was carried out on a total of 13 yeast strains. All
the yeast strains grew in the maintenance medium at 30 C. Only
two strains grew at 42 C and no strain grew at 45 C. The strains
that grew at 42 C were incubated in the production medium and
evaluated for biomass and ethanol production. The isolated strains
were found capable of growing and fermenting glucose at 42 C
with an ethanol yield of 85–89% in 36 h (data not shown). The
potential isolate which showed higher ethanol yield of 89%was isolated
from fruit waste and was identified at NCIM, Pune, India. The
isolate showed closest homology to Kluyveromyces sp. (nearest
species marxianus) using ITS rDNA gene sequencing. Phylogenetic
tree based on ITS rDNA gene sequences (669 bp) showing relationship
of strain with other type species or members of genus (Table 1
and Fig. 1a). The numbers at nodes represent bootstrap values
(based on a resampling of 1000) (Felsenstein, 1985). Bootstrap values
above 50% are shown. The genbank accession numbers of
sequences of each reference species are listed in parenthesis. Bar
at the end of tree indicates nucleotide substitutions per site. Gaps
in sequencing alignment and missing data were omitted. After
trimming there were 443 positions in final sequence set used to
infer evolutionary relationships. Sequence data for the newly isolated
yeast strain was shown in Fig. 1b.