Low GPA, 321 GRE, Questionable Rec Letter quality

Hello all,

I am currently planning to apply to grad school but is currently having some doubts about my qualifications. I have a around a 2.7 for my undergraduate GPA (Wildlife Science) and most grad programs seems to require 3.0 or higher. I was not all that interested in my undergrad major but finished my bachelors nonetheless. This was partly due to financial and time restraints but I have to admit in retrospect is was primarily due to my lack of maturity and ability to the incentive to change colleges at the time (went to a specialized environment school).

Having worked in the field for around a year, I realize the environmental field is just not for me. I decided to change fields apply for a master program in Microbiology/biophysics/physics (I scored A/A- on all course related to cell bio in undergrad).I taken my GRE already and scored a 321 (162 verbal, 159 quant, 3.5 AWA) and have one good letter of recommendation from a work supervisor. I unsure about the other two letters as I was a very reticent student and did not establish close relationship with my professors.

What are my chances of being accepted to a master program with my current credentials? I want to apply for the coming fall semester (earliest deadline is Jan 15) but should I seek to take some additional courses at a graduate school before I want to pursue a master degree in a field that differs from my bachelors?