Fermentación controlada de aceitunas verdes picholine marroquí mediante cepas de lactobacilos degradantes de oleuropeína

The control of the spontaneous fermentation process of un-debittered Moroccan Picholine green olives was undertaken basing the inoculation with two lactobacilli strains (Lactobacillus plantarum S175 and Lactobacillus pentosus S100). These strains, previously selected in our laboratory for their oleuropein-degrading capacity, were inoculated in olives brined at 5% of NaCl, and then incubated at 30 ÅãC. The physico-chemical parameters (pH, free acidity, reducing sugars, sodium chloride, oleuropein and its hydrolysis products), and the microbiological parameters (mesophilic aerobic bacteria, coliforms, Staphylococcus, lactic acid bacteria and yeasts and moulds), were regularly analyzed during the fermentation time. The results obtained showed the effectiveness of the lactic acid bacteria strains to develop suitable oleuropein biodegradation and controlled lactic fermentation processes more than the un-inoculated olives (control). This result was confirmed by the rapid elimination of coliforms and staphylococcus, the accumulation of hydroxytyrosol as a result of oleuropein biodegradation, and a drastic reduction in spoiled olives with good quality fermented olives.Se llevó a cabo el control del proceso de fermentación espontánea de aceitunas verdes sin desamargar picholine marroquí basado en la inoculación con dos cepas de lactobacilos (Lactobacillus plantarum S175 y Lactobacillus pentosus S100). Estas cepas, seleccionadas previamente en nuestro laboratorio por su capacidad de degradar a la oleuropeína, se inocularon en las aceitunas en salmuera al 5 % de NaCl, y después se incubaron a 30 °C. Los parámetros físico-químicos (pH, acidez libre, reducción de azúcares, cloruro sódico, oleuropeína y sus productos de hidrólisis) y los parámetros microbiológicos (bacterias aerobias mesófilas, coliformes, estafilococos, bacterias lácticas y levaduras y mohos), fueron analizados regularmente durante el tiempo de fermentación. Los resultados obtenidos mostraron la eficacia de las cepas de bacterias lácticas para desarrollar una adecuada biodegradación de la oleuropeina y los procesos de fermentación láctica controlados más que en el caso de las aceitunas no inoculadas (control). Estos resultados fueron confirmados por la rápida eliminación de coliformes y estafilococos, por la acumulación de hidroxitirosol como resultado de biodegradación de la oleuropeína, y por ladrástica reducción de aceitunas estropeadas y por la buena calidad de las aceitunas fermentadas

Lactic acid bacteria (LAB) and their bacteriocins as alternative biotechnological tools to control Listeria monocytogenes biofilms in food processing facilities

International audienceBacteriocins are antimicrobial peptides produced by bacteria Gram-negative and Gram-positive, including lactic acid bacteria (LAB), organisms that are traditionally used in food preservation practices. Bacteriocins have been shown to have an aptitude as biofilm controlling agents in Listeria monocytogenes biofilms, a major risk for consumers and the food industry. Biofilms protect pathogens from sanitization procedures, allowing them to survive and persist in processing facilities, resulting in the cross-contamination of the end products. Studies have been undertaken on bacteriocinogenic LAB, their bacteriocins, and bioengineered bacteriocin derivatives for controlling L. monocytogenes biofilms on different surfaces through inhibition, competition, exclusion, and displacement. These alternative strategies can be considered promising in preventing the development of resistance to conventional sanitizers and disinfectants. Bacteriocins are "friendly" antimicrobial agents, and with high prevalence in nature, they do not have any known associated public health risk. Most trials have been carried out in vitro, on food contact materials such as polystyrene and stainless steel, while there have been few studies performed in situ to consolidate the results observed in vitro. There are strategies that can be employed for prevention and eradication of L. monocytogenes biofilms (such as the establishment of standard cleaning procedures using the available agents at proper concentrations). However, commercial cocktails using alternatives compounds recognized as safe and environmental friendly can be an alternative approach to be applied by the industries in the future

Water soluble ruthenium (II) complex derived from optically pure limonene and its microencapsulation are efficient tools against bacterial food pathogens biofilms: Escherichia coli, Staphylococcus aureus, Enteroccocus faecalis and Listeria monocytogenes

Bioactive aminooxime ligands based on optically pure (R)-limonene have been synthesized in two steps. Their ruthenium (II) cationic water-soluble complex was prepared by a reaction between dichloro (para-cymene) ruthenium (II) dimers and aminooxime ligands in a 1:2 molar ratio. Antibacterial and antibiofilm activities of the synthetized complex were assessed against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. The results revealed that the ruthenium (II) complex has higher antibacterial and antibiofilm activities in comparison with free ligands or the enantiopure (R)-limonene. Moreover, microencapsulation of this complex reduced its cytotoxicity and improved their minimum inhibitory concentration and antibiofilm activity toward the considered bacteria. The ruthenium (II) complex targets the bacterial cell membrane, which leads to rapid leakage of intracellular potassium. Our study suggests that the developed ruthenium (II) complexes could be useful as an alternative to conventional disinfectants

Assessment of the temporal change in groundwater quality when stored at different temperatures in household conditions, in the equatorial region of Central Africa

The study carried out aimed at assessing the impact of groundwater storage temperature at household conditions on the temporal evolution of electrical conductivity and the future of heterotrophic aerobe bacteria (HAB). The storage duration was 7 days and the considered temperatures were 3, 10, 18 and 25°C. The electrical conductivity during storage reached 829 µS/cm at 3 - 18°C and 850 µS/cm at 25°C. The maximum HAB abundance was 9 x 103 cfu/ml at 3°C, 41 x 103 cfu/ml at 10°C, 44 x 103 cfu/ml at 18°C and 93 x 103 cfu/ml at 25°C. At the 3rd and 7th days storage at 3°C, changes in bacterial abundances values were significantly in the same direction as those of electrical conductivity (P < 0.05). The highest cell apparent growth rate at the 3rd day storage was 0.249 d-1 at 3°C, 0.559 d-1 at 10°C, 0.924 d-1 at 18°C and 1.233 d-1 at 25°C. However, at the 7th day storage, it was 0.362 d-1 at 3°C, 0.497 d-1 at 10°C, 0.690 d-1 at 18°C and 0.672 d-1 at 25°C. At the 3rd day storage, a decrease in cell abundance was noted in 90% of samples at 3°C and the cell apparent inhibitory rate varied from 0.012 to 0.989 d-1. The storage of groundwater in households’ conditions for a long period would alter its bacteriological quality.SCOPUS: ar.jinfo:eu-repo/semantics/publishe