Microorganisms have been among the most important sources of bioactive compounds, from antibiotics to chemotherapeutic drugs. Anticancer peptides are reported to have efficient tissue penetration and uptake by heterogeneous cancer cells, endowed with intrinsic activity or synergized with existing therapeutics, which is of major relevance for the battle against chemotherapeutic drug resistance. The growing interest in lactic acid bacteria bacteriocins for therapeutic purposes has required new classifications for emerging bacteriocins. Genome mining has allowed the exploration of sea microbial diversity, leading to the finding of new substances with therapeutic potential. Synergy in the effect on tumor volumes was also observed where nisin appeared to potentially increase the anticancer therapeutic potential of doxorubicin (DOX) by approximately one and half times just after four weeks of chemotherapy. Nisin and DOX reduced the mean tumor burden by 14% and 51.3%, respectively, after four weeks of treatment.