# How to prevent a word in chapter name from capitalizing in footer globally defined by fancyhdr?

I am trying to write my thesis in LaTeX. My problem is, I have defined chapter and section titles as header and footer using package fancyhdr. I have certain words in chapter and section titles (Scientific names of bacteria) which should not be capitalized by convention. So my header and footer are all capitalized (including those names which should be in small letters). How can I prevent these names from getting capitalized in the header and footer? In this example I have included "Escherichia coli" as the name. How can I get header and footer capitalized while this name will be intact as "Escherichia coli"?

\documentclass[a4paper,11pt]{book}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyfoot{}
\fancyfoot[L]{\textsl{\rightmark}}
\usepackage{lipsum}
\begin{document}
\chapter{Chapter name with capital text and Escherichia coli }
\lipsum[2-4]
\section{Section name with  Escherichia coli}
\lipsum[2-4]
\end{document}


To force lower case: \lowercase{...}

\documentclass[a4paper,11pt]{book}
\usepackage{fancyhdr}
\pagestyle{fancy}