A muslim convert suspected of intending to detonate a suicide bomb in Broadmead also displayed a concerning interest in germ warfare, a court heard.

Winchester Crown Court heard AS level student Isa Ibrahim questioned micro biologist Dr Sarah Maddocks when she gave a lecture into how science could be fun at City of Bristol College in November 2007.

Dr Maddocks told the court that afterwards a student (Ibrahim) approached her, told her that his father was a pathologist who dealt with dead people on a regular basis and a lot have them could have died through bacterial infection.

She told the court: "He had a lot of interest in bacteria. He stated he had been reading books and he knew bacteria had been used to kill people.

"He asked which were the best sorts of bacteria and where they might be found and how they might be used.

"He used Anthrax as an example and I answered his questions in the broadest terms I could."

Dr Maddocks, who formerly worked at the Government Research Facility at Porton Down, told the court that after fobbing the persistent student off she discussed the matter with her lecturer husband Robert Hawkins, and he reported it to college authorities.

It is claimed 20-year-old Ibrahim became infatuated with the so-called cult of hate against the people of the West, fuelled by Muslim extremists, and he wanted to follow in the footsteps of his 9/11 and 77 hero martyrs by detonating a suicide bomb in the Galleries shopping mall.

Friends said how the drug addict changed his Western-style of dress, grew a long beard and adopted the garb of a Muslim.

When police raided his one-bedroom flat at Comb Paddock, Westbury-on-Trym, in April 2008, in a fridge they found a family-sized biscuit tin containing a home made explosive, an electrical circuit with button detonator and, hanging on the back of a bedroom door, a white cotton vest with panels at the front and back similar to those worn by suicide bombers.

The bomb was called and carried out a controlled explosion of the biscuit tin explosive device in an alleyway near his home.

Ibrahim, a former public schoolboy, denies making an explosive substance with intent, in that he made the explosive hexamethylene triperoxide diamine (HMTD) with the intention to endanger life or cause serious injury to property in the UK.

He also denies the preparation of terrorism acts, in that he researched the manufacture of explosives, bought materials to make them, made them and also bought materials to detonate them – as well as identifying a place to do so.

He has pleaded guilty to simply making an explosive substance.

Mr Hawkins told the court he lectured Ibrahim in AS level biology and described him as an "average student" whose attendance was generally good.

He told the jury he invited his partner Dr Maddocks to give the lecture at the college and he was present when Ibrahim asked her questions afterwards.

He said: "His questions were about bacteria and the history of bacteria usage. He mentioned a book he was reading on Anthrax.

"After Christmas I decided to report it to the authorities at the college."

Mr Hawkins said that from 2008 he noticed Ibrahim had changed from wearing tracksuits to Muslim dress, and he was slightly more chatty in class.

He said: "He would talk about silly things like computer games and programmes like the X Files.

"He never talked to me about his religion or faith. On occasion he was late and said he had been to prayers."

Earlier Gemma Angell (corr) told the court she was Ibrahim's project support worker from October 2007 when he had a flat with Priority Youth Housing Association at St Georges House in St Georges Road, Bristol.

She said she was aware Ibrahim followed the Muslim faith and wore Muslim dress, though he wore Western dress of jeans, T-shirts and trainers on occasion – as he was wearing in court.

Miss Angell confirmed that when Ibrahim arrived at the premises he was a user of heroin and crack cocaine and when more fully into his Muslim practices, visiting his mosque five to six times a day, appeared to be using fewer drugs.

She said Ibrahim's room was very messy and quite dirty, he had issues with some female staff and he would call her "thick" if she made errors like spelling mistakes.

She said: "He was very intelligent. He was very open to debate things, he was very strong in his opinions and he seemed to be well read and well educated."

Miss Angell recalled how Ibrahim said it was unfair Muslim people were always portrayed as terrorists, but she didn't enter into conversations on matters in which she had no knowledge.

She told the court Ibrahim had been aiming to study in Birmingham and had wanted to be re-housed to East Bristol, where he felt he had a lot of connections with the Muslim community.

She described how Ibrahim could be "obnoxious" and he was "quite overly-sexualised" with female staff.

She said she had seen Ibrahim spit at someone, but she had not seen him to be violent.

The court heard housing association staff records showed there was an episode when Ibrahim was very distressed after injecting himself in the leg, when his leg turned blue and he was taken to hospital, thinking he would have to have it amputated.

It turned out that what actually happened was dye from his jeans turned his leg blue, the court heard.

Marco Van-Tintelen (corr), a project manager at St Georges House, said he asked Ibrahim to take down an A4 size poster from his wall, which appeared to be two blocks and a broken aircraft representing the 9/11 terrorist attack.

He recalled an incident in which two female residents had bullied Ibrahim, suggesting he had "man boobs" and he was "so sad".

The case continues.