Project Background #

Just about a year ago in November 2021, New Delhi, the cap­i­tal of India wit­nessed a lock­down like sit­u­a­tion not be­cause of the pan­demic but ow­ing to se­vere air pol­lu­tion. This was caused pri­mar­ily be­cause of ‘stubble burn­ing’ which is the burn­ing of crop residues by farm­ers in their agri­cul­tural fields. In India only ce­re­als pro­duce 352 met­ric tons of crop residues every year. Post-harvest farm­ers find burn­ing the most con­ve­nient way of clear­ing their fields for the next crop. However, this prac­tice is ex­tremely detri­men­tal for the health of hu­mans, an­i­mals, mi­crobes, soil and the en­vi­ron­ment. It causes res­pi­ra­tory ail­ments in hu­mans, af­fects soil mi­cro­biome and bio­di­ver­sity, re­duces soil fer­til­ity which im­pacts the health of plants and se­verely pol­lutes the air.

Inspiration #

The ef­fect of this prac­tice man­i­fests it­self as thick smog that cov­ers ma­jor cities like New Delhi. Our cam­pus is based in Bhopal, a city lo­cated south of the cap­i­tal Delhi. Last year all of us wit­nessed scenes of stub­ble burn­ing close to our cam­pus (Video ref). This caused a lot of ir­ri­ta­tion to the eyes, res­pi­ra­tory ail­ments among many of our friends and loss of vis­i­bil­ity that led to flight can­cel­la­tions and road ac­ci­dents. We were also aware and wor­ried about the loss of soil fer­til­ity and bio­di­ver­sity in fields around our cam­pus. As iGEM pro­motes ‘Local peo­ple solv­ing lo­cal prob­lems, us­ing syn­thetic bi­ol­o­gy’ we thought that it would be a great chal­lenge to try to tackle this ‘burning prob­lem’. Additionally, dur­ing our vis­its to nearby vil­lages for out­reach ac­tiv­i­ties we saw that ‘plastic pol­lu­tion’ is a ma­jor men­ace there. The non-degrad­able plas­tics were pil­ing on road­sides and lit­tered in fields and wa­ter bod­ies. We thought that in­stead of burn­ing the crop residues if we could con­vert it into bio­plas­tic us­ing ge­net­i­cally en­gi­neered bac­te­ria it would serve dual pur­pose of re­duc­ing stub­ble burn­ing and non-degrad­able plas­tic waste.

Current Solution #

Currently, only a few al­ter­na­tives are avail­able to the farmer to stop them from burn­ing their fields. There are some me­chan­i­cal means of re­mov­ing the stub­bles us­ing an at­tach­ment to trac­tors. Some bail­ing ma­chines are also used to ex­tract crop residues and pack them into bri­quettes. However, these processes are of­ten not avail­able to the mar­ginal farm­ers who find it hard to af­ford. Some farm­ers try to man­u­ally har­vest the crop residues to be used as fod­der, but this is ex­tremely labour in­ten­sive and of­ten leads to in­jury to farm­ers. Recently, IARI (Indian Agricultural Research Institute) came up with a con­sor­tium of sev­eral fun­gal species called ‘Pusa de­com­poser’ that can de­com­pose paddy straw by break­ing down the cel­lu­lose and other cell wall car­bo­hy­drates. The de­tails of this con­coc­tion are pro­pri­etary ma­te­r­ial and not yet avail­able in the pub­lic do­main. Although, the ‘Pusa de­com­poser’ is a great ini­tia­tive which also acted as an in­spi­ra­tion for us, we be­lieve that us­ing syn­thetic bi­ol­ogy we might be able to pre­pare a for­mu­la­tion that can in­crease the reper­toire of so­lu­tions and might even be more ef­fec­tive.

Our Solution #

Bacillus sub­tilis is a Gram-positive, rod-shaped aer­o­bic bac­te­ria very com­monly found in the soil. It is known to in­ter­act with sev­eral plants in­clud­ing ce­re­als and oilseed plants. The genes en­cod­ing for cel­lu­lases, pecti­nases, xy­lanase and ligni­nolytic en­zymes which can de­grade lig­no­cel­lu­losic com­po­nents are cloned into vec­tors with strong and in­ducible pro­mot­ers and then used to trans­form E.coli and Bacillus sub­tilis. The engineered bac­te­ria can se­crete en­zymes that can break down the stub­ble of var­i­ous crops, in­clud­ing rice, wheat, soy­beans, mil­lets, and maize. The en­gi­neered Bacillus can be added to the stub­ble in the fields to pro­mote de­com­po­si­tion of the stub­ble. The engineered bac­te­r­ial strain can be in­duced un­der in vitro con­di­tions to par­tially de­com­pose wheat and paddy straw to ex­tract vanillin which can fur­ther be con­verted into bio­plas­tic.

References #

1. https://​www.re­search­gate.net/​pub­li­ca­tion/​289202446_­Pos­si­ble_rea­son­s_and_­farm­er­s_aware­ness_­to­ward­s_crop_residue_burn­ing_an_overview_and_a_­case_s­tudy_from_Mirza­pur_vil­lage_of_Ku­ruk­shetra_dis­tric­t_In­dia
2. https://​www.rvo.nl/​sites/​de­fault/​files/​2019/​12/​MVO-Ned­er­land-rap­port-In­dia.pdf
3. https://​www.mdpi.com/​1660-4601/​16/​5/​832
4. https://​www.teriin.org/​sites/​de­fault/​files/​2020-01/​crop-residue-man­age­ment.pdf
5. https://​en.wikipedia.org/​wiki/​Stub­ble_burn­ing