The visitors were reduced to 10 men for the last 40 minutes after James Tarkowski was sent-off for a second bookable offence but the Bees produced a resilient rearguard action to emerge deserved winners.
Orient had enjoyed the better of the first period with David Mooney , Dean Cox and Romain Vincelot all going close before the Bees took the lead with their only shot in target in the first-half and that came in added time with Trotta's sublime finish.
Collecting a pass from Adam Forshaw 20 yards from goal, he directed his shot wide of the diving Eldin Jakupovic and into the bottom right-hand corner of the goal.
Despite their numerical advantage, Orient failed to cause too many concerns for their opponents although Moses Odubajo was denied by a reactionary save by David Button who saved the winger's shot with his knees.
However, it was the Bees who came closest to finding the net again when Alan Judge thumped a shot against the upright in the dying seconds.
Britt Assombalonga struck twice in two second-half minutes as Peterborough saw off MK Dons 2-0 and strengthened their grip on the final League One play-off place.
Assombalonga struck first in the 58th minute when he finished off Josh McQuoid's teasing low cross before slotting home from the penalty spot after Conor Washington was fouled.
The victory increased Posh's lead over MK Dons in the final play-off spot to six points - with Assombalonga and co also boasting a game in hand.
Wolves remain top despite a 0-0 draw at home to Shrewsbury which ended their run of nine straight wins.
Both sides had chances to snatch victory late on but Wolves’ Matt Doherty and the visitors’ Tom Eaves both spurned their openings.
Rotherham left it late to rescue a point once again as substitute Nicky Adams fired in priceless 88th-minute leveller to draw 1-1 with 10-man Walsall.
It had looked as though Milan Lalkovic’s effort would be enough for the away side, but their task was made more difficult when Ben Purkiss was dismissed 20 minutes from time.
And Adams fired home to stretch the hosts’ unbeaten run to 12.
- Sports & Recreation
- David Mooney
- James Tarkowski
- Romain Vincelot
- Adam Forshaw