Automated Analysis of Intratidal Dynamics of Alveolar Geometry From Microscopic Endoscopy

Alveolar parenchyma, the gas exchange area of the respiratory system, is prone to mechanical damage during mechanical ventilation. Development of lung protective ventilation strategies therefore requires a better understanding of alveolar dynamics during mechanical ventilation. In this paper, we propose a novel method for automated analysis of the intratidal geometry of subpleural alveoli based on the evaluation of video frames recorded from alveolar microscopy in an experimental setting. Our method includes the recording with a microscopic endoscope, feature extraction from image data, the analysis of a single frame, the tracking and analysis of single alveoli in a video sequence, and the evaluation of the obtained sequence of alveolar geometry data. Our method enables automated analysis of 2-D alveolar geometry with sufficient temporal resolution to follow intratidal dynamics. The developed method and the reproducibility of the results were successfully validated with manually segmented video frames.      

Screening of a natural biodiversity of lactic and propionic acid bacteria for folate and vitamin B12 production in supplemented whey permeate

Lactic acid bacteria (LAB) and propionic acid bacteria (PAB) are known for the production of several important nutraceuticals. We screened 151 LAB and 100 PAB of different origins (fermented foods and feeds) for extracellular folate and intracellular vitamin B12 production in supplemented whey permeate using a standardized microbiological assay (folate) and HPLC (vitamin B12). Five LAB strains belonging to the species Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus brevis and Lactobacillus fermentum exhibited high extracellular folate productions, with a maximum yield of 397 ± 60 ng mL^?1 for L. plantarum SM39. The highest vitamin B12 production was measured for Propionibacterium freudenreichii DF15 with 2.5 μg mL^?1. Screening a large biodiversity of LAB and PAB led to a representative image of the distribution of folate and vitamin B12 production by these genera and enabled the identification of high natural folate and vitamin B12 producing strains with high potential for applications in fermented foods.     

Facultative anaerobic halophilic and alkaliphilic bacteria isolated from a natural smear ecosystem inhibit Listeria growth in early ripening stages

In vitro and in situ anti-listerial properties of 3 strains of Facultative Anaerobic Halophilic and Alkaliphilic (FAHA) species, i.e. Alkalibacterium kapii ALK 6, Marinilactibacillus psychrotolerans ALK 9 and Facklamia tabacinasalis ALK 1, were investigated. The 3 strains were isolated from a smear ecosystem originating from a commercial Raclette type cheese and exhibiting strong anti-listerial activity in situ on cheese surface.In a first step, strains were tested in vitro for production of antimicrobial compounds against Listeria innocua 81000-1 and Listeria ivanovii HPB 28. M. psychrotolerans ALK 9 inhibited both indicator strains in spot-on-the-lawn tests while A. kapii ALK 6 showed no inhibiting effect. F. tabacinasalis ALK 1 exerted an in vitro inhibition on L. ivanovii HPB 28, but induced the formation of dense ball-shaped microcolonies of L. innocua 81000-1 in the soft agar, a typical biofilm microstructure. The extent of the biofilm zone was enhanced when F. tabacinasalis ALK 1 and M. psychrotolerans ALK 9 were tested together.In a second step, different combinations of strains were applied on Raclette cheeses ripened at pilot scale and contaminated with 50 cfu/cm²L. innocua at day 7. A control flora of 6 strains, isolated from ecosystem F and corresponding to species commonly found on smear cheeses, was applied on control and test cheeses. In test cheeses, we investigated the impact on Listeria growth of the addition of the 3 FAHA strains, applied as single or mixed cultures. A 1-log inhibition was obtained at day 15 on cheeses treated with FAHA strains applied either as single or mixed cultures. This 1-log inhibition was correlated with the development of FAHA species that reached their maximal count at day 15.This study suggests that the development of FAHA species in early ripening likely contributes to the initial part of the in situ inhibition exerted by the complex cheese surface ecosystem investigated.     

Detection of antifungal properties in Lactobacillus paracasei subsp. paracasei SM20, SM29, and SM63 and molecular typing of the strains

Lactobacilli isolated from different food and feed samples such as raw milk, cheese, yoghurt, olives, sour dough, as well as corn and grass silage, were screened for their antifungal activities. Out of 1,424 isolates tested, 82 were shown to be inhibitory to different yeasts (Candida spp. and Zygosaccharomyces bailii) and a Penicillium sp., which were previously isolated from spoiled yoghurt and fruits. Carbohydrate fermentation patterns suggested that a substantial portion, 25%, belonged to the Lactobacillus casei group, including L. casei, L. paracasei, and L. rhamnosus. The isolates SM20 (DSM14514), SM29 (DSM14515), and SM63 (DSM14516) were classified by PCR using species-specific primers to target the corresponding type strains (L. casei, L. paracasei, and L. rhamnosus) as controls. Further molecular typing methods such as randomly amplified polymorphic DNA, pulsed-field gel electrophoresis, and sequencing analysis of the 16S rRNA gene allowed classifying strains SM20, SM29, and SM63 as L. paracasei subsp. paracasei in accordance with the new reclassification of the L. casei group proposed by Collins et al.