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In recent years, production and use of bio-pesticides have increasing and replacing some synthetic chemical pesticides applied to food commodities. In this review, biological control is focused as an alternative, to some synthetic chemical treatments that cause environmental, human health, and food quality risks. In addition, several phytopathogenic microorganisms have developed resistance to some of these synthetic chemicals and become more difficult to control. Worldwide, the bio-pesticides market is growing annually at a rate of 44% in North America, 20% in Europe and Oceania, 10% in Latin and South American countries and 6% in Asia. Use of agro-industrial wastes and solid-state fermentation (SSF) technology offers an alternative to bio-pesticide production with advantages versus conventional submerged fermentations, as reduced cost and energy consumption, low production of residual water and high stability products. In this review, recent data about state of art regarding bio-pesticides production under SSF on agroindustrial wastes will be discussed. SSF can be defined as a microbial process that generally occurs on solid material in the absence of free water. This material has the ability to absorb water with or without soluble nutrients, since the substrate must have water to support the microorganism's growth and metabolism. Changes in water content are analyzed in order to select the conditions for a future process, where water stress can be combined with the best spore production conditions, obtaining in this way an inexpensive biotechnological option for modern agriculture in developing countries.

ABSTRACT

The solid-state fermentation (SSF) is the best option to produce spores of biological control agents (BCA), because the spores have a long shelf life, compared with the obtained in liquid cultures. The spore production under SSF conditions using polyethylene bioreactors (bag-type) is a new topic. Only little information mainly about bioreactors design and adequate conditions to spore production is available. The main aim of this study was to use the corn cob as substrate in SSF and produce spores of the fungi BCA Trichoderma asperellum in a polyethylene bioreactor. In the process was added biomass of the phytopathogenic fungi Colletotrichum gloeosporioides and Phytophthora capsici as inducers of hydrolase enzymes (endoglucanases, exoglucanases and chitinases). It is possible to obtain high levels of spores, cellulases and chitinases using a polyethylene bioreactor under SSF conditions by T. asperellum and corn cob as substrate. Under the SSF conditions evaluated, the biomass of C. gloeosporioides has an inducer effect just on the spore production. However, P. capsici have effect on all response variables evaluated. The spore production was twice when used P. capsici as inducer. The most influential factor under SSF was the moisture. Levels of 66 and 50% of this factor increase the yield in all response variables evaluated (sporulation, cellulases and chitinases), C. gloeosporioides and P. capsici, respectively.

Ellagitannins (ETs) are phytochemicals derived from secondary metabolism associated to defense system, with complex chemical structures, which have high participation during all stages of protection against microbial infection. In this study, we report the fungal biodegradation of a bioactive ET, named punicaline which was recovered and purified from pomegranate peels and used as carbon source in solid-state culture (SSC) using polyurethane as solid support. SSC was kinetically monitored during 36 h of incubation time. ETs and glycosides consumption were spectrophotometrically determined. Ellagic acid (EA) accumulation was analyzed by HPLC. Several enzymatic activities were assayed (cellulase, xylanase, β-glucosydase, polyphenoloxidase, tannase, and ET hydrolyzing activities). The consumption levels of ETs and glycosides were 66 and 40%, while EA accumulation reached 42.02 mg g(-1). A differential pattern of enzymatic activities was found; evidence from our studies suggests that the ET hydrolyzing activity is directly associated to EA accumulation, and production of this enzyme may represent the most critical step to successfully develop a bioprocess for production of an important bioactive compound, the EA.

fermentation did not improve the production of spores from Trichoderma since similar results were obtained in the process without forced aeration. On this report, we reach concentrations greater than 1 × 10 9 spores per gram of substrate at 96-120 h of culture, indicating a feasible approach of agro-industrial wastes as a substrate for the biomass production.