Evaluation of thermomechanical pretreatment for enzymatic hydrolysis of pure microcrystalline cellulose and cellulose from Brewers’ spent grain

Microcrystalline cellulose (Avicel PH102) and Brewers’ spent grain (BSG) were subjected to Détente Instantanée Contrôlée (DIC) thermomechanical pre-treatment before exposure to cellulases (Celluclast 1.5 L). In a first part, we showed that the addition of β-glucosidase (Novozym-188) increased the hydrolysis yield of Avicel. A maximal theoretical yield (100%), was obtained for 5 and 10 g/L of Avicel using a mixture of Celluclast 1.5 L/Novozym-188. After DIC pre-treatments, the initial rate and final yield of hydrolysis decreased in comparison with those from untreated microcrystalline cellulose. This phenomenon may be due to the modification of the crystallinity of pure cellulose and the formation of inhibitors during the pre-treatment. In a second part, BSG was thermomechanically pre-treated and hydrolyzed. The results showed that the hydrolysis yield of BSG treated at pressure levels between 2 and 7 bar during 15 min was strongly improved compared to hydrolysis yield of untreated BSG. The optimized hydrolysis process, under intensive DIC conditions, achieved a glucose yield corresponding to 100% of the theoretical cellulose value. The morphology of BSG samples was studied with Scanning Electronic Microscopy (SEM) and highlighted that the structure of pre-treated BSG showed an important disruption compared to the rigid structure of untreated BSG.     

A systematic review of the evidence of reduced allergenicity and clinical benefit of food hydrolysates in dogs with cutaneous adverse food reactions

Several hydrolysate-based diets have been commercialized for helping diagnose or treat dogs with cutaneous adverse food reactions (CAFR). This systematic review was performed to examine the evidence in favour of reduced immunological and clinical allergenicity of hydrolysates in dogs with CAFR. Citation databases, meeting abstracts and article bibliographies were scanned for relevant citations, and companies were contacted to provide unpublished reports. Eleven studies relevant to this study were identified. Some evidence of reduced serum IgE binding to a soy hydrolysate (1 study) and decreased intradermal test reactivity to hydrolysed proteins (three studies) was found. In four reports, the feeding of dogs suspected of having CAFR with hydrolysate-based diets reduced or eliminated clinical signs in a variable proportion of subjects. The percentage of dogs with CAFR that still reacted to these hydrolysate-based diets could not be assessed, however. Importantly, up to 50% of dogs with CAFR enrolled in three controlled studies exhibited increases in clinical signs after ingesting partial hydrolysates derived from foods to which they were hypersensitive. In conclusion, the limited number of studies undertaken point to reduced – but not eliminated – immunological and clinical allergenicity of hydrolysate-based commercial diets. A variable proportion of dogs with CAFR will exhibit a worsening of clinical signs when fed partial hydrolysates. Clinicians must weigh the clinical benefit of these diets versus their high cost and low risk of reduced appetence or gastrointestinal sign development. At this time, hydrolysate-containing diets are probably best used in dogs suspected not to be hypersensitive to their individual components.     

Clinical and immunological heterogeneity of canine subepidermal blistering dermatoses with anti‐laminin‐332 (laminin‐5) auto‐antibodies

Laminin‐332 (laminin‐5) is a basement membrane heterotrimeric protein composed of alpha‐3, beta‐3 and gamma‐2 laminin chains. Laminin‐332 polypeptides are targeted by auto‐antibodies in human patients with mucous membrane (cicatricial) pemphigoid or, more rarely, subepidermal vesicular diseases that resemble epidermolysis bullosa acquisita (EBA) or bullous pemphigoid (BP). The objectives of this report were to characterize the clinical, histopathological and immunological characteristics of nine dogs with auto‐antibodies targeting laminin‐332. Immunological investigations consisted of direct immunofluorescence (IF), indirect IF with intact and salt‐split canine gingival, and salt‐split normal or laminin‐332‐deficient human skin, immunoblotting with purified human laminin‐332 and immunoblotting with recombinant NC1 domain of human collagen VII. All dogs exhibited varying degrees of skin blistering and ulceration associated with microscopic subepidermal vesiculation with or without inflammatory cells. Indirect IF established that circulating IgG auto‐antibodies bound the dermal side of salt‐split canine lip and human skin. In five dogs, IgG variably recognized the basement membrane of laminin‐332‐deficient human skin (three dogs negative, two dogs positive). In all nine dogs, IgG auto‐antibodies detected purified human laminin‐332 by immunoblotting. In two dogs, additional targeting of collagen VII‐NC1 was present. These observations establish laminin‐332 as a novel basement membrane antigen in dogs with autoimmune blistering diseases with variable clinical phenotypes. The names ‘acquired junctional epidermolysis bullosa’, ‘anti‐laminin‐332 mucous membrane pemphigoid (MMP)’ and ‘mixed auto‐immune subepidermal blistering dermatosis’ are proposed for dogs with clinical signs reminiscent of EBA, MMP or BP respectively.     

Mining the genetic diversity of Ehrlichia ruminantium using map genes family

Understanding bacterial genetic diversity is crucial to comprehend pathogenesis. Ehrlichia ruminantium (E. ruminantium), a tick-transmitted intracellular bacterial pathogen, causes heartwater disease in ruminants. This model rickettsia, whose genome has been recently sequenced, is restricted to neutrophils and reticulo-endothelial cells of its mammalian host and to the midgut and salivary glands of its vector tick. E. ruminantium harbors a multigene family encoding for 16 outer membrane proteins including MAP1, a major antigenic protein. All the 16 map paralogs are expressed in bovine endothelial cells and some are specifically translated in the tick or in the mammalian host.In this study, we carried out phylogenetic analyses of E. ruminantium using sequences of 6 MAP proteins, MAP1, MAP1-2, MAP1-6, MAP1-5, MAP1+1 and MAP1-14, localized either in the center or at the borders of the map genes cluster.We show that (i) map1 gene is a good tool to characterize the genetic diversity among Africa, Caribbean islands and Madagascar strains including new emerging isolates of E. ruminantium; (ii) the different map paralogs define different genotypes showing divergent evolution; (iii) there is no correlation between all MAP genotypes and the geographic origins of the strains; (iv) The genetic diversity revealed by MAP proteins is conserved whatever is the scale of strains sampling (village, region, continent) and thus was not related to the different timing of strains introduction, i.e. continuous introduction of strains versus punctual introduction (Africa versus Caribbean islands).These results provide therefore a significant advance towards the management of E. ruminantium diversity. The differential evolution of these paralogs suggests specific roles of these proteins in host–vector–pathogen interactions that could be crucial for developing broad-spectrum vaccines.     

Efficacy of an oral live vaccine for veterinary use against pseudotuberculosis

Pseudotuberculosis, an infection caused by the ubiquitous enteropathogenic bacterium Yersinia pseudotuberculosis, is a recurrent veterinary problem in livestock and zoo animals. The only vaccine currently available in zoos is Pseudovac (a mixture of killed strains of various serotypes), but its efficacy is not well established. We show here that Pseudovac does not protect guinea pigs against a severe Y. pseudotuberculosis infection. We thus evaluated the possibility of using a live attenuated Y. pseudotuberculosis strain (IP32680) as an oral vaccine against animal pseudotuberculosis. We report that IP32680 is avirulent for guinea pigs and induces a strong IgG response against various serotypes of Y. pseudotuberculosis. One and two oral inoculations of IP32680 provided 50% and 83% protection, respectively against a severe infection with a highly pathogenic strain. The avirulent Y. pseudotuberculosis IP32680 is therefore much more protective than Pseudovac and may represent a valuable oral vaccine against pseudotuberculosis in zoo animals.     

Field validation of chlordecone soil sequestration by organic matter addition

Purpose

The use of chlordecone (CLD) has caused pollution of soils, which are now a source of contamination for crops and ecosystems. Because of its long-term impacts on human health, exposure to CLD is a public health concern and contamination of crops by CLD must be limited. To this end, we conducted field trials on chlordecone sequestration in soil with added compost.

Materials and methods

The impact of added compost on chlordecone sequestration was measured in nitisols. After characterization of the soil, the transfer of chlordecone from soil to water was assessed in a leaching experiment and from soil to two crop plants in a nitisol plot. Finally, to understand the underlying processes, changes in CLD content were measured in soil fractions and soil porous properties were assessed after the addition of compost.

Results and discussion

A rapid seven-fold decrease in water extractable CLD was observed in amended soils. Five percent amendment led to a significant reduction in the contamination of crops by CLD; edible radish tubers were 50% more contaminated without added compost and cucumber fruits were 60% more contaminated. After the addition of compost, CLD content increased in the fraction of pre-humified or partially mineralized organic debris. Finally, in contrast to andosols, adding compost to nitisols did not affect the soil microstructure.

Conclusions

Increasing chlordecone sequestration by adding compost could be an alternative solution until soil decontamination techniques become available. This could be a provisional way to control further release of CLD from contaminated soils towards other environmental compartments.