Here's an excerpt from the more recent article about the trials:
While the exact causes are unclear, IBD is known to be the result of an overactive immune response that is linked to an imbalance of the normal types of bacteria found in the gut.
Several recent studies have identified butyric acid as a potential therapeutic agent for IBD. Some gut bacteria produce butyric acid naturally in the intestines, but in IBD patients some of these strains are heavily depleted.
Trials in mice have shown that injecting one such strain Faecalibacterium prausnitzii into the digestive tract is effective at restoring normal levels of gut bacteria and treating the symptoms of IBD.
In addition, novel identified butyrate-producing strains, such as Butyricicoccus pullicaecorum, have been shown to exert similar effects.
Butyric acid has well-known anti-inflammatory effects and is able to strengthen intestinal wall cells - making it an ideal therapeutic agent against IBD.
In addition to butyric acid, it is hypothesized that strains such as F. prausnitzii and B.pullicaecorum secrete other anti-inflammatory compounds that may enhance the therapeutic effect.
Prof. Filip Van Immerseel, a medical microbiologist from Ghent University in Belgium said that a new treatment for IBD would be welcomed.
“Conventional drug therapy has limited effectiveness and considerable side effects. Probiotics are live bacterial supplements or food ingredients, which when taken in sufficient numbers confer health benefits to the host,” he said.
There are likely more strains of gut bacteria that produce butyric acid, so I wouldn't be surprised to see a probiotic treatment in the coming months or years.