In .bib file:
@article{Kurahashi_Yokota2004,
author = "Kurahashi, M. and Yokota, A.",
title = "Agarivorans albus gen. nov., sp. nov., a $\gamma$-proteobacterium isolated from marine animals",
journal = "International Journal of Systematic and Evolutionary Microbiology",
volume = "54",
year = "2004",
pages = "693--697"
}
Output:

See that the \gamma proteobacterium word is broken up. I want to keep the gamma together on the same line as proteobacterium.

\hbox{$\gamma$-proteobacterium}, but I'm not sure if this is good for a citation. AFAIK there is some non-hyphenating dash, but I can't recall its name. – Martin Scharrer♦ May 25 '11 at 17:36\nobreakdashesand is to be followed by the requested sequence of one to three-. – egreg May 26 '11 at 6:36