Fashion designer Stella McCartney has unveiled a two-piece outfit made using a leather alternative grown from mycelium, making her among the first luxury fashion designers to turn the biomaterial into wearable clothing.

The jet-black co-ord consists of a bustier and utilitarian trousers made from recycled nylon scuba, with panels of the vegan leather layered on top to create a structured finish almost like armour.

These appliques were created in collaboration with American materials company Bolt Threads, using a version of its Mylo mycelium leather.

Originally launched in 2018, Mylo has so far only been used to create smaller accessories such as a prototype of McCarney's chain-trimmed Falabella bag that was exhibited as part of the Fashioned From Nature exhibition at the V&A.

Last year a number of major fashion houses including McCartney, Adidas and Gucci parent company Kering formed a consortium and invested seven-figure sums to scale up production for mass use.

As a result of this collaboration, the material can now be grown into pieces that are large enough to be fashioned into trousers, and flexible enough to be used in clothing.

"The material used in these two garments not only represents a huge step forward in both aesthetics and performance of biomaterials but also marks the beginning of the rollout of product-ready Mylo," said Bolt Threads founder Dan Widmaier.

"This is tangible progress toward large-scale production where Mylo can make a significant positive impact on our planet."

Mycelium is the structure of thread-like filaments that fungi use to grow, much like the roots of a tree, which in this case is fed with organic biomass including sawdust before being placed on a growing matt.

Once it has expanded and bonded to form a kind of foamy layer, the material is harvested, tanned and dyed by the same tanneries that normally process animal leather.

Public data on Mylo's environmental footprint will not be available until later this year when Bolt Threads is set to undertake a full lifecycle assessment of the material.

But the company claims that it consumes fewer natural resources and emits fewer greenhouse gases in its production than both animal and plastic-based synthetic leather.

Unlike Hermès' mycelium leather Victoria bag, which will be available for purchase from the end of 2021, McCartney's Mylo garments are one-off pieces that will not be mass-produced, even though the British designer has committed herself to integrating the material into future collections.

"These rare, exclusive pieces embody our shared commitment with Bolt Threads to innovate a kinder fashion industry – one that sees the birth of beautiful, luxurious materials as opposed to the death of our fellow creates and the planet," McCartney explained.