Improving of Red Colorants Production by a New Penicillium purpurogenum Strain in Submerged Culture and the Effect of Different Parameters in Their Stability Val eria Carvalho Santos-Ebinuma Dept. of Biochemical and Pharmaceutical Technology, University of S~ ao Paulo, 05508-900 S~ ao Paulo, SP, Brazil In^ esConceic¸~ ao Roberto Dept. of Biotechnology, Engineering College of Lorena, University of S~ ao Paulo, 12602-810 Lorena, SP, Brazil Maria Francisca Simas Teixeira Culture Collection DPUA/UFAM, Universidade Federal do Amazonas, 69.077-000 Manaus, AM, Brazil Adalberto Pessoa Jr Dept. of Biochemical and Pharmaceutical Technology, University of S~ ao Paulo, 05508-900 S~ ao Paulo, SP, Brazil DOI 10.1002/btpr.1720 Published online April 1, 2013 in Wiley Online Library (wileyonlinelibrary.com) There is a worldwide interest in the development of processes for colorants production from natural sources such as microorganism. The aim of this study was to optimize red colo- rants production by Penicillium purpurogenum DPUA 1275 and to evaluate the effect of pH, temperature, salts and polymers on the stability of these colorants. Under optimized condi- tions, a 78% increase in red colorants production was achieved. The best pH and tempera- ture conditions were obtained at pH 8.0 and 70  C, respectively. In the presence of salts NaCl and Na 2 SO 4 , both at concentrations of 0.1 and 0.5 M in Mcllvaine buffer (pH 8.0), the red colorants showed good stability. In the presence of both polymers polyethylene glycol and sodium polyacrylate, the red colorants kept their color intensity. Thus, this study presents characteristics of red colorants produced by P. purpurogenum that can be applied in different industries after toxicological examination. V C 2013 American Institute of Chemi- cal Engineers Biotechnol. Prog., 29:778–785, 2013 Keywords: red colorants, fungi, submerged culture, stability, polymers Introduction Nowadays, the use of most synthetic colorants has decreased as a result of the federal regulatory agencies deci- sion to reduce the number of approved synthetic colorants, 1 based on recent studies that showed these compounds are toxic and potentially carcinogenic. 2 Consequently, the use of natural colorants is increasingly emphasized. 3 In the food industry, for instance, the colorants market in 2007 was esti- mated at $1.15 billion, 2.5% higher than in 2004 $1.07 bil- lion. In this market, $465 million came from natural colorants, a 4.6% increase over 2004. 4 Natural colorants are extracted from natural sources such as plants, insect tissues, 5–7 and microorganisms. 8–11 The pro- duction by the latter is of great interest to industries because microorganisms can rapidly grow and lead to high productiv- ity and product availability throughout the year. 9,11 Further- more, microbial colorants are often more stable and soluble than plant- or animal-derived ones. 12 Among microorganisms, fungi are reported as potent colo- rant producers. 13,14 The diversity of fungal colorants is not only found in their chemical structures but also in the color range of their compounds. 15 It has recently been reported in the literature 2,4,11,16 that Penicillium strains are potential producers of natural colorants, which have polyketides structures and chromophore similar to Monascus colorants. 15 N-glutarylmonascorubramine and N-glutarylrubropunctamine (Figure 1) were the water-soluble Monascus colorants dis- covered in the extracellular colorant extract obtained from the liquid medium of Penicillium purpurogenum. 15 The structures of polyketides are known to have unlocalized neg- ative charge ð-electrons, as they often contain polyunsatu- rated functionality, i.e., ring systems, one or more carbonyl groups, carboxylic acid, and ester or amide functional groups exhibiting UV–vis spectra characteristic. 17 Furthermore, studies found in the literature confirm that Penicillium spp. have no toxic effects and their pigments are biodegradable. 14 Also, in Penicillium species, P. purpuroge- num can produce colorants not only in solid medium but also in liquid media. 11 In a study performed by Teixeira et al., 18 P. purpurogenum DPUA 1275 showed potential to produce natural colorants with antimicrobial activities and absence of toxicity to brine shrimp Artemia salina. Bioprod- ucts produced by microorganisms must receive the quality certificate GRAS (Generally Recognized As Safe) from the Correspondence concerning this article should be addressed to V. C. Santos-Ebinuma at lelacarvalho21@usp.br. 778 V C 2013 American Institute of Chemical Engineers