Biomedical Engineering Reference
In-Depth Information
Introduction
The meat and brewery industries produce large quantities of wastewaters with high
chemical oxygen demand (COD) and biochemical oxygen demand (BOD), thus representing
a serious environmental problem in Santiago de Cuba. Therefore, these effluents must be
treated by using clean technologies for reducing their initial COD, as reported before for these
wastes (Salas et al., 2006) and for other wastes from food industry (Murado et al., 1993;
Roukas, 1999; Guerra & Pastrana, 2003).
In this way, different food wastes (
e
.
g
. mussel processing wastes, brewery wastes, whey)
have been used as culture media in submerged cultures to produce different metabolites
including amylases (Murado et al., 1993; 1997), pullulan (Roukas, 1999) and bacteriocins
(Guerra & Pastrana, 2003; Guerra et al., 2005), among others. However, comparative studies
between submerged liquid fermentation (SLF) and solid state fermentation (SSF) claim
higher yields and other advantages for products produced by SSF, such as low energy
requirements, lower availability of water that reduces the possibilities of contamination by
bacteria and yeast, small volumes of polluting effluents and low downstream processing cost
(Hesseltine, 1972; Cannel and Moo-Young, 1980; Aidoo et al., 1981; Steinkraus, 1984;
Kumar & Lonsane, 1990; Kumaran et al., 1997; Raimbault, 1998; Guerra et al., 2003). Some
agro-industrial products (
e.g
. sugar cane bagasse, spent brewing grains, cassava starch, sweet
potato residue and peanut meal residue, palm fiber, banana waste) have been used for
metabolite production in SSF (Krishna & Chandrasekaran, 1996; Yang and Wang, 1999;
Francis et al., 2002; Milagres et al., 2004; John et al., 2006; Spier et al., 2006; Mazutti et al.,
2006; 2007; Balkan & Ertan, 2007; Laxmi et al., 2008).
Amylases production by
Aspergillus
species in both submerged and solid state
cultivations using different food wastes or agricultural residues has been thoroughly studied
(Gigras et al., 2002; Ellaiah et al., 2002; Francis et al., 2002; 2003; Salas et al., 2006). These
enzymes have not only been used in fermentation processes, but also in processed food
industry and in the textile and paper industries (Pandey et al., 2000; Ellaiah et al., 2002;
Gigras et al., 2002). The production of amylases in SLF and SSF is affected by a variety of
physicochemical factors, including the composition of the growth medium, incubation
temperature, pH, aeration, concentration and type of the carbon, phosphate and nitrogen
sources, size and age of the inoculum, particle size and moisture level of the substrate (Gigras
et al., 2002; Salas et al., 2006; Balkan & Ertan, 2007). Therefore, after selecting a culture
medium for amylase production, it is necessary to determine the optimal culture conditions to
improve enzyme production at a low production cost (Salas et al., 2006; Spier et al., 2006;
Balkan & Ertan, 2007).
Considering the substantial availability of highly rich wastewaters and sugar cane
bagasse at very low prices by local brewery, meat and sugar processing plants of Santiago de
Cuba, their use as culture media or support material for different bioproductions could
provide profitable substrates for a low cost production. This approach allows the protection of
the environment by recycling these residues in production of amylases by
Aspergillus oryzae
strain FQB-01.
In the present study, both brewery and meat processing wastes of Santiago de Cuba were
evaluated as culture media for amylase production by
A. oryzae
strain FQB-01 under
submerged culture conditions. The reduction in COD in both wastes after biological treatment
