Major colorectal surgery, i.e. surgery involving a wide colon resection and/or a very low anastomosis, remains problematic, despite great advances in medico-pharmaceutical treatment, improvement in surgical techniques, and sophisticated postoperative management. Such surgery is still accompanied by an unacceptably high morbidity of 15% to 23.2% leading to an increase in the number of ventilatory support days, prolongation of total hospital stay, significantly higher medical costs, patient suffering, and, unfortunately mortality. Worse than this, nowadays, infections and sepsis are by far the most common morbidities, either as initial cause or as a consequence of another complication, such as anastomotic leakage. Ongoing clinical studies have reported probiotic therapies to be beneficial in elective surgery cases, since they have been shown to successfully modulate the GI flora in a plethora of medical settings and in critically ill and trauma patients. More precisely, recent randomized controlled studies and meta-analyses in elective surgery and abdominal surgery patients have demonstrated that the perioperative use of probiotics is safe and reduces both the incidence of postoperative wound infections, sepsis, post-operative pneumonia and other infections, and the necessary duration of hospital stay and length of antibiotic therapy. However, there exist few controlled, large-scale, trials comparing the current standard treatment with the probiotic concept and showing the superiority of the latter in colonic surgery with regard to a reduced complication rate. Therefore, the investigators decided to conduct a randomized controlled trial to investigate the impact of a probiotics treatment protocol on postoperative morbidity in an open elective colonic surgery cohort. The major objective is to evidence a reduction in 30-day infectious, surgery-related morbidity: any surgical site infection; organ specific infections; systemic infections and anastomotic leakage. Minor objectives related to the reduction in other non-infectious complications, as well as the assessment of outcome indicators such as the number of days in postoperative ileus, on mechanical ventilation, stay in ICU, total hospitalization and mortality in the 30-day post-operative period.