Screening the Rumen of Balochi Camel (Camelus dromedarius) and Cashmere Goat (Capra hircus) to Isolate Enzyme-Producing Bacteria as Potential Additives for Animal Feed.

Rumen microbiology has made a significant contribution to the discovery of biodegradation processes, which convert nutrients into energy for ruminants. Therefore, understanding the enzymatic potential in the rumen of different animal species is essential for developing efficient microbial feed additives. The aim of this study was to isolate enzyme-producing bacteria (EPBs) from the rumen of the Balochi camel (Camelus dromedarius) and Cashmere goat (Capra hircus) as potential additives for animal feed. The EPBs were screened based on the hydrolysis of carboxyl methyl cellulose, tannin, starch, and bovine serum albumin. The isolates were then subjected to enzyme activity assays and molecular characterization. Additionally, they were evaluated for their antagonistic effects, antibiotic susceptibility, and growth in acidic, bile, and saline media. Thirteen enzyme-producing strains were identified in the rumen of the camels and goats, belonging to the genera Klebsiella, Escherichia, Raoultella, Enterobacter and Pectobacterium. The highest and lowest tannase activities were recorded for Escherichia coli GHMGHE41 (10.46 Um/l-1) and Raoultella planticola GHMGHE15 (1.83 Um/l-1), respectively. Enterobacter cloacae GHMGHE18 (2.03 U/ml) was the most effective cellulolytic isolate, compared to Klebsiella strains (1.05 Um/l-1). The highest protease producer was Klebsiella pneumoniae GHMGHE13 (3.00 U/ml-1), while Escherichia coli GHMGHE17 (1.13 U/ml-1) had the lowest activity. Klebsiella pneumoniae GHMGHE13 (1.55 U/ml-1) and Enterobacter cloacae GHMGHE19 (1.26 U/ml-1) were the highest and lowest producers of amylase, respectively. The strains exhibited mixed responses to antibiotics and remained stable under stressful conditions. These findings indicate that ruminal EPBs have the potential to be used in animal feed, pending further in vivo studies.

[Nuclear organization and expression of milk protein genes]. / Organisation nucléaire et expression des gènes des protéines du lait.

Milk protein gene expression varies during the pregnancy/lactation cycle under the influence of lactogenic hormones which induce the activation of several transcription factors. Beyond this activation modifying the binding properties of these factors to their consensus sequences, their interactions with DNA is regulated by variations of the chromatin structure. In the nuclei of the mammary epithelial cell, the three dimensional organisation of the chromatin loops, located between matrix attachment regions, is now being studied. The main milk components are organised in supramolecular structures. Milk fat globules are made of a triglyceride core enwrapped by a tripartite membrane originating from various intracellular compartments. The caseins, the main milk proteins, form aggregates: the casein micelles. Their gradual aggregation in the secretory pathway is initiated as soon as from the endoplasmic reticulum. The mesostructures of the milk fat globule and of the casein micelle remain to be elucidated. Our goal is to make some progress into the understanding of the molecular and cellular mechanisms involved in the formation of these milk products.