How to add the search form in Bootstrap theme?
After some search I figure out the following solution, it is working, But the issue is it is applying to search_block_form also, might be function lsubtheme_bootstrap_search_form_wrapper($variables) is the reason, which is getting applied everywhere. Might be giving False positive result. 

PLEASE anybody have any suggestion, how to imptove this, I am trying will update. 

Codes in template.php

function lsubtheme_preprocess_page(&amp;$variables){
  $search_form = drupal_get_form('search_form');
  $search_box = drupal_render($search_form);
  $variables['search_box'] = $search_box;
}

/*
 *  Form alter to add missing bootstrap classes and role to search form.
 */

function lsubtheme_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if ($form_id == 'search_form') {
    $form['#attributes']['class'][] = 'navbar-form navbar-left';
    $form['#attributes']['role'][] = 'search';
  }
}


function lsubtheme_bootstrap_search_form_wrapper($variables) {

  $output = '&lt;div class="form-group"&gt;';
  $output .= $variables['element']['#children'];
  $output .= ' &lt;div class="form-group"&gt;';
  $output .= '&lt;button type="submit" class="btn btn-default"&gt;Search&lt;/button&gt;';
  $output .= '&lt;/div&gt;';
  $output .= '&lt;/div&gt;';
  return $output;
}


Code in page.tpl.php

 &lt;?php print $search_box; ?&gt;