## 4 Discussion  
Microbiota manipulations by administration of probiotic have been demonstrated to be effective in a number of clinical conditions (e.g., respiratory, oral, urogenital, and intestinal) to ameliorate the history of either infective or non-infective diseases, probably modulating the local and systemic immune functions [18; 19; 20; 21; 22; 23]. Herein, for the first time, we report a description of the anaerobic population of gut microbiota in stool samples from controls subjects and patients with sporadic colorectal adenoma/polyp (SCA/P). Our attention to the anaerobic species has been driven by numerous data present in literature reporting a strong correlation between stool anaerobic bacteria and CRC. [PERSON] et al., reviewing the relationship between microbiota and the development of CRC, reported highest levels of carcinogen production in association with gut anaerobic bacteria [23]. [PERSON] and coll reported that genera _Bacteroides_, the 25% of anaerobic bacteria [3], are strongly associated with CRC, stating also that CRC development is associated with _Bacteroides fragilis_[24]. Farther, epidemiological studies reported that incidence and mortality of CRC higher in African American (AA) than in Caucasian American (CA) associated to the more abundant presence of _Bacteroides_ in AAs than in CAs patients [25]. Figure 1: Gut microbiota species recognized in the fecal samples of the control and sporadic colorectal adenomas/polyp (SCA/P) subjects: (**a**) Gram\(-\)bacteria; (**b**) Gram+ bacteria. Our data revealed that a different gut microbiota pattern, particularly evident for the _Bacteroides_ genus, was found in the two group of subjects studied. However, our data suggest other possible important implications. First of all, the two groups of stools are characterized by different species of bacteria, _Bacteroides stercoris_ and _Parabacteroides distasonis_ for control group and _Bacteroides fragilis_ and _Prevotella melaninigenica_ for SCA/P group. Data from literature assign specific roles to these bacteria in relation to CRC. _Parabacteroides distasonis_ (Pa.d.) has been reported abundant in mice's stools and inversely associated with intestinal tumor burden and IL-1\(\beta\) concentrations [26]. In their report, the Authors attributed to Pa.d. anti-inflammatory and anti-cancer properties that are likely mediated by the suppression of TLR4 and Akt signaling, as well as promotion of apoptosis [27]. CRC development has been associated with increased presence of _Bacteroides fragilis_ (B.f.) in gut microbiota [24]. This Gram-negative, facultative anaerbe specie constitutes an appreciable proportion of the human gastrointestinal tract microbiota and, as typical of most gram-negative bacilli, it secretes an unusually complex mixture of neurotoxins, including the extremely pro-inflammatory lipopolysaccharideaccharide [11]. In this regard, it is important to underline the presence of the Gram+ _Pediococcus pentasaceus_ (Pe.p.) in fecal samples of control subjects since this specie is able to eliminate the lipopolysaccharideaccharide (LPS) components, which can cause intestinal inflammation [28], that is a biological condition known to predispose to CRC development [29; 30]. Furthermore, _Pediococcus pentasaceus_, found only in controls, showed antiproliferative activity on colon cancer cells directly adhering to those and triggering the bioproduction of short-chain fatty acids (SCFAs), mainly butyric and propionic acids, suggesting for the use of this bacteria specie as an alternative bio-prophylactic and biotherapeutic strategy for colon cancer [31]. Finally, we detected _B. fragilis_ only in subjects with endoscopic pre-cancerous lesions (SCA/P). What metabolic situation can derive from a shift of gut microbiota or, in general, by the induction of dysbiosis? From a biochemical point of view, dysbiosis has some common characteristics: the number of bacteria that produce SCFAs is reduced.