foreach (var item in lstArquivo)
        {
            using (FileStream entrada = new FileStream(item + ext_txt, FileMode.OpenOrCreate, FileAccess.ReadWrite))
            {
                using (FileStream outputstream = new FileStream(item + ext_zip, FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    using (GZipStream gzip = new GZipStream(outputstream, CompressionMode.Compress))
                    {
                        entrada.CopyTo(gzip);
                    }
                }
            }
        }

    }