Microvirga sp. symbiovar mediterranense nodulates Lupinus cosentinii grown wild in Morocco.

AIM: To analyse the diversity of nodule-forming bacteria isolated from Lupinus cosentinii naturally grown in the Maamora cork oak forest (Rabat, Morocco). METHODS AND RESULTS: Of the 31 bacterial strains, four were selected based on their REP-PCR fingerprinting that were studied by sequencing and phylogenetic analysis of their 16S rRNA, gyrB, dnaK, recA and rpoB housekeeping genes as well as the nodC symbiotic gene. The nearly complete 16S rRNA gene sequence of the four representative strains showed that they are related to Tunisian strains of genus Microvirga isolated from L. micranthus with nucleotide identity values ranging from 98·67 to 97·13%. The single and concatenated sequences of the 16S rRNA, gyrB, dnaK, recA and rpoB housekeeping genes indicated that the L. cosentinii-isolated strains had 99·2-99·9% similarities with the Tunisian L. micranthus microsymbionts. The nodC gene phylogeny revealed that the Moroccan strains clustered in the newly described mediterranense symbiovar, and nodulation tests showed that they nodulated not only L. cosentinii but also L. angustifolius, L. luteus and L. albus. CONCLUSIONS: To the best of our knowledge, this is the first report concerning the isolation, molecular identification and phylogenetic diversity of L. cosentinii nodule-forming endosymbionts and of their description as members of the Microvirga genus. SIGNIFICANCE AND IMPACT OF THE STUDY: In this work, we show that Microvirga sp. can be isolated from root nodules of wild-grown L. cosentinii in Northeast Africa, that selected strains also nodulate L. angustifolius, L. luteus and L. albus, and that they belong to symbiovar mediterranense. In addition, our data support that the ability of Microvirga to nodulate lupines could be related to the soil pH, its geographical distribution being more widespread than expected.

Impact of DOM from composted "alperujo" on soil structure, AM fungi, microbial activity and growth of Medicago sativa.

Water-soluble extracts from compost may represent an alternative nutrient and organic matter source for crop production under drip irrigation. Dissolved organic matter (DOM), extracted from composted "alperujo", the main by-product from the Spanish olive oil industry, was applied to soil alone or in combination with either Glomus intraradices Schenck and Smith or a mixture of G. intraradices, Glomus deserticola (Trappe, Bloss. and Menge) and Glomus mosseae (Nicol and Gerd.) Gerd. and Trappe. Response measurements included mycorrhizal colonisation, nutrient uptake and growth of Medicago sativa and microbiological and physical properties in the rhizosphere. Dissolved organic matter was added to soil at concentrations of 0, 50, 100 or 300mgCkg(-1) substrate. During the four months of the experiment, the plants were harvested three times. Both mycorrhizal inoculation treatments significantly increased soil aggregate stability. Only the mycorrhizal inoculations increased microbial biomass C and protease and phosphatase activities and decreased water-soluble C, particularly the mixture of arbuscular mycorrhizal fungi. At the third harvest, the greatest increase in growth of M. sativa was observed in the inoculated plants with shoot biomass being 38% greater than for plants grown in the soil amended with the highest dose of DOM and 57% greater than for control plants. The addition of DOM was not sufficient to restore soil structure and microbial activity and did not affect the mycorrhizal development of introduced populations of arbuscular mycorrhizal fungi, but, depending on the dose, its fertiliser efficiency for improving plant growth was apparent.

Effects of the forced ventilation on composting of a solid olive-mill by-product ("alperujo") managed by mechanical turning.

The evaluation of the most suitable aeration technology for olive-mill by-product "alperujo" (AL) composting was carried out by using two identical piles prepared by mixing AL with a bulking agent (fresh cow bedding) and a mature compost (as inoculant). Forced ventilation was employed in conjunction with mechanical turning in one of the piles, whereas only mechanical turning was used in the other pile. These two treatment methods were evaluated by assessing process efficiency and end-product quality. The results show that the composting process was completed in less time when forced ventilation was coupled with mechanical turning. A slight delay in the evolution of pH, C/N ratio, and biodegradation of fats and organic matter was observed when only turning was employed. However, the recommended method for composting AL was mechanical turning without forced ventilation since the composition of the end-product in this case was comparable to the composted AL using forced ventilation coupled with mechanical turning. Furthermore, there were substantial economic savings by selecting mechanical turning alone, which included capital costs for equipment.

[4 families with silent cholinesterase variant]. / Estudio de cuatro familias con variante colinesterásica silente.

We report 4 patients who had apnea of variable duration after succinylcholine administration to facilitate orotracheal intubation during anesthesia. After ruling out other causes of apnea unrelated to succinylcholine, we genotyped the cholinesterase variants of these patients and their relatives measuring total plasmatic cholinesterase activity and using the inhibitors dibucaine and fluoride. We found the silent gene (Es1) both in homozygosis (2 cases) and heterozygosis, with the atypical gene (Ea11) (2 cases). The relevance of preoperative screening to prevent anesthetic accidents is emphasized.