Characterization and production of shiitake (Lentinula edodes) in Mexico using supplemented sawdust

The cultivation of shiitake in Latin America started during the early 1980's, and several attempts for its commercial cultivation have been carried out during the last decade in Guatemala, Colombia, Mexico, Argentina and Brazil. However, a major constrain has been the lack of basic research, allowing further development. In this work, we studied two genotypes of Lentinula edodes (CP-7 and CP-163) selected from 16 strains being used in the region at different levels, in order to assess their mycelial growth rate in Petri dishes, as well as yield (biologic efficiency, production rate) and quality of fruit bodies, using 10 different formulations of supplemented sawdust from a common Mexican oak tree (Quercus acutifolia Neé). The best mycelial development was 8.5 mm/day for the genotype CP-163 cultivated on 70% Quercus sawdust, 10% corn-cobs, 10% maize stubble, 7% wheat bran and 3% rice meal. The highest yield was recorded in the genotype CP-7, using 60% Quercus sawdust, 28.5% corn-cobs, 10% maize stubble, 1.5% gypsum, thiamine (100 mg/kg), and magnesium sulfate (20 g/100 kg); reaching a biologic efficiency of 103%, a production rate of 1.3, and a high proportion (41.8%) of fruit bodies, having good commercial quality (41 to 70 g fresh weight, > 12 cm cap diameter and 96.5% of regular shape). On the basis of this study, this last genotype and formulation was recommended, as well as to establish a breeding program at the molecular level for shiitake production on a large scale in Mexico or other Latin American countries.Keywords: Edible mushrooms, genotypes, substrates, mycelial growth rate, biologic efficienc

Antibacterial activity of crude extracts from Mexican plants against methicillin-resistant Staphylococcus

The aim of this study was to evaluate the antimicrobial activity of 36 extracts from 18 vegetal species used as soap, insecticides, insect repellent and for the treatment of several diseases likely associated to microorganisms. The vegetal species were collected in Oaxaca, Puebla and Veracruz States, México. The extracts were evaluated against isolates of nosocomial infections of Staphylococcus aureus and Staphylococcus coagulase negative resistant to Methicillin by a modificated agar diffusion method. The results demonstrate an important antibacterial effect in vitro, against all of the strains of Staphylococcus tested mainly with those from Vernonanthura oaxacana, Trixis silvatica, and with those of Perezia hebeclada. The minimum inhibitory concentration for V. oaxacana and P. hebeclada was 250 μg/disc and for T. silvatica it was 15 μg/disc. These extracts showed an important potential that would contribute to the development of new agents against infections by Staphylococcus.Key words: Crude extracts, antimicrobial activity, intrahospitalary infections, methicillin-resistant Staphylococcus coagulase negative

Phytoremediation of soils contaminated with heavy metals: techniques and strategies

Environmental pollution by heavy metals and metalloids has become a severe problem worldwide, as soils became increasingly contaminated, posing a threat to ecosystems and ultimately to human health. The decision to remediate a soil depends on the present and future value of the soil, the cost of remediation, the risk posed by the soil, and the perception of that risk by the population and decision-makers. Traditional technologies to remediate soils usually rely on excavation of the contaminated soil, often disposed of as a hazardous waste with or without a previous treatment. The use of plants to remove or immobilize toxic elements has arisen as a very promising alternative to conventional technologies. The use of plants to remediate soils derived from the observation of wild species found in specific environments, evolved to the use of fast growing crops, and later on led to the development of genetically-modified plants. Phytotechnologies include a wide range of technologies that can be applied to remediate soils through stabilization, volatilization, accumulation and sequestration of toxic metals. In this chapter we describe the impacts of heavy metals in plants and the most important phytotechnologies available to remediate soil and substrates