Insights Into the Complexity of Yeast Extract Peptides and Their Utilization by Streptococcus thermophilus

Streptococcus thermophilus, an extensively used lactic starter, is generally produced in yeast extract-based media containing a complex mixture of peptides whose exact composition remains elusive. In this work, we aimed at investigating the peptide content of a commercial yeast extract (YE) and identifying dynamics of peptide utilization during the growth of the industrial S. thermophilus N4L strain, cultivated in 1 l bioreactors under pH-regulation. To reach that goal, we set up a complete analytical workflow based on mass spectrometry (peptidomics). About 4,600 different oligopeptides ranging from 6 to more than 30 amino acids in length were identified during the time-course of the experiment. Due to the low spectral abundance of individual peptides, we performed a clustering approach to decipher the rules of peptide utilization during fermentation. The physicochemical characteristics of consumed peptides perfectly matched the known affinities of the oligopeptide transport system of S. thermophilus. Moreover, by analyzing such a large number of peptides, we were able to establish that peptide net charge is the major factor for oligopeptide transport in S. thermophilus N4L

Thyroid disease in progressive systemic sclerosis Patología tiroídea en la esclerosis sistémica progresiv a.

There is no agreement wither thyroid disease is a common feature of progressive systemic sclerosis (PSS). We evaluated 28 patients with proven PSS with determinations of T3, T4, TSH and Tg as well as antimicrosomal autoantibodies. Radioactive I uptake, thyroid scintigraphy, TRH test and fine needle biopsy were performed in selected patients. Twelve (43%) patients had clinical or laboratory evidence of thyroid dysfunction. Four patients had euthyroid goiter, 3 had evidence of autoimmune disease, 2 had chronic Hashimoto's thyroiditis, 1 was hypothyroid, 1 hyperthyroid and one has subacute thyroiditis. The CREST variant of PSS was most commonly associated with thyroid pathology. Our results indicated that thyroid disease is frequently associated to PSS. A complete clinical and laboratory evaluation is needed to confirm its presence