I have a Bachelor's degree in journalism, and I'm starting a Master's degree program next year. I'd like to teach in a university - is it possible to do so with only a Master's?
In the unedited post, you mentioned portuguese, so I'll take a chance and guess brazilian. It is statistically likely, you don't seem to be from portugal, but that still leaves portuguese speaking african countries...
Considering public universities in/near SP, RJ, MG, the whole south and some capitals, you won't even be able to apply, they require PhDs all around, with high competition. In the federal universities farthest away from these centers (like AP, RO, RR) a masters would be enough in most cases. These openings are probably available even with the recession, not many candidates willing to relocate, and, without PhD, the salary will be kinda low... (~ 4k BRL)
On the other hand, if you go to the private universities, yes, totally. With the exception to some of the most prestigious (like PUC, Mackenzie, etc), that require PhDs. In the smaller ones, most of the professors do not even have masters. Low pay, no research and tons of courses tho...
If you combine both and consider a small private university farthest away from the economic centers, they might not even consider you, saying that you are overqualified....
Your question is short and missing much information, so I will try to cover a few basics.
In general, in many countries, having a Phd is required. The requirement is not always a university rule, but mostly an internal department decision, or a factor of previous experience.
There are many fields in which a Phd is not required, such as Business, Art, Architecture, Music, etc. While many of those fields also have what is referred to as a 'terminal degree', meaning the highest degree in their respective field which may not be a Phd, those departments also will hire non-Phd faculty.
This will also vary depending on what type of school. Community college typically will be willing to accept a broader range of people. Universities may be teaching or research focused. In that case, you may have a masters with a high level of research experience, and a research university will welcome it.
Industry is also greatly important in some fields. In something like Industrial Design, having a bachelors or masters with 7 years of product design at Apple may very well carry you far.
I am not familiar with journalism in particular, but would imagine if you were a journalist at a well known paper, a school focusing on sending students to industry and not academia may look favorably on you.
So how do you become a teacher? In my opinion, your best chances are either getting a masters degree, then working at a renowned journalism company, build a reputation and a name, and over a few years start looking into Universities. Otherwise, pursue a Phd. Having a Phd is not a guarantee for a teaching position either, so you may very well end up spending 6 years on your Phd, not having worked in industry, and find it difficult to get a job.