| dc.description.abstract | Microbial biodiversity has shown a great evolution in the last decades, due to the isolation and
identification of the microbiota from environments that have not yet been studied, such as the
Caatinga, and also, due to its direct participation in the production of several biotechnological
metabolites. The Aspergillus genus is considered a producer of secondary metabolites, studied
in different biotechnological processes. Agro-industrial residues have a large amount of micro
and macronutrients that can be used in the formulation of fermentation media, as they can
reduce the costs of production processes. Citric acid is an organic compound produced by
microorganisms and used in several industrial processes. The selection studies of Aspergillus
samples isolated from the Caatinga of Pernambuco in solid medium to determine the best citric
acid producing sample, varying the pH and temperature values, for 144 hours, in triplicate, with
daily monitoring for 24 h. Then, the best sample was submitted to the submerged fermentation
process, for 144 h, 180 rpm and 37o C. After the production tests in submerged fermentation,
agro-industrial residues were tested through the formulation of means and the use of a factorial
design 23 carried out under the same conditions as the control medium. The samples collected
every 24 h were subjected to determination of the growth curve, pH variation and determination
of the citric acid concentration by chemical method and potentiometry produced in the control
and alternative media. The results obtained show that the sample called UCP1357 showed the
largest characteristic halos of citric acid, 8.0 cm, pH 8.5 and temperature of 37 ° C. The
production of citric acid through submerged fermentation showed that the medium called
“medium 2” which presented the highest quantification of citric acid produced, in the period of
144 hours, an amount of 7.22g / L. After identifying the best microorganism and medium, a
factorial design 23 was carried out using pineapple, acerola, orange and lemon residues for
the production of citric acid under the same conditions previously established. The results
obtained detected a great interaction between the orange and lemon residues, presenting a
citric acid activity of 15.29 g / L. The feasibility of reusing agro-industrial residues in the
formulation of means of production of biotechnological metabolites of high added value, has
emerged as a viable alternative in recent decades. Several alternative means have been
developed and described in scientific works, and the results obtained have been quite
satisfactory. | eng |
