Non-italic text in author name for Biblatex

Question

I am using this package in Overleaf for referencing for a Nature journal, but Nature journal requirement is that 'et al' shouldn't be in italics. Can please someone help me to solve this problem.

\usepackage[bibstyle=nature,citestyle=nature,backend=bibtex,style=nature,biblabel=brackets,giveninits=true,abbreviate=true,doi=false,eprint=true,url=false,isbn=false,block=space,natbib]{biblatex}

Answer 1

biblatex-nature enforces italics for "et al." in the bibmacro name:andothers (nature.bbx, ll. 216-231 in v1.3d)

\renewbibmacro*{name:andothers}{%
  \ifboolexpr
    {
      test {\ifnumequal{\value{listcount}}{\value{liststop}}}
      and
      test \ifmorenames
    }
    {
      \ifnumgreater{\value{liststop}}{1}
        {\finalandcomma}
        {}%
      \andothersdelim
      \mkbibemph{\bibstring{andothers}}%
    }
    {}%
}

(This is slightly unidiomatic. \mkbibemph{\bibstring{andothers}} would more naturally be \bibstring[\mkbibemph]{andothers}. Or even better a wrapper command instead of bare \mkbibemph.)

If we want no italic andothers string across languages we will want to redefine this macro to get rid of the \mkbibemph.

\documentclass{article}
\usepackage[
  backend=biber,
  style=nature,
]{biblatex}
\renewbibmacro*{name:andothers}{%
  \ifboolexpr
    {
      test {\ifnumequal{\value{listcount}}{\value{liststop}}}
      and
      test \ifmorenames
    }
    {
      \ifnumgreater{\value{liststop}}{1}
        {\finalandcomma}
        {}%
      \andothersdelim
      \bibstring{andothers}%
    }
    {}%
}
\addbibresource{biblatex-examples.bib}
\begin{document}
Lorem \citeauthor{companion}
ipsum \textcite{aksin}
\printbibliography
\end{document}

Answer 2

You could use

\DefineBibliographyStrings{english}{andothers = {\upshape et al\adddot}}

to format the et al. in whatever way you like (if you write in another language but English, adjust this accordingly).

Please note that I had to remove the biblabel=brackets from your code fragment to avoid it throwing an error.

\documentclass{article}
\usepackage[
  %bibstyle=nature,
  %citestyle=nature,
  backend=bibtex,
  style=nature,
  %biblabel=brackets,
  giveninits=true,
  abbreviate=true,
  doi=false,
  eprint=true,
  url=false,
  isbn=false,
  block=space,
  natbib
]{biblatex}
\DefineBibliographyStrings{english}{andothers = {\upshape et al\adddot}}
\addbibresource{biblatex-examples.bib}
\begin{document}
\citeauthor{companion}
\printbibliography
\end{document}