<PAGE>
                                                                    EXHIBIT 10.6

                               DONLAR CORPORATION
                           2003 EQUITY INCENTIVE PLAN

         1.       PURPOSE.

         The purpose of the Donlar Corporation 2003 Equity Incentive Plan (the
"Plan") is to enhance the ability of Donlar Corporation (the "Company") and any
subsidiaries to attract and retain the best available personnel for positions of
substantial responsibility, to provide additional incentive to such personnel
and to promote the success of the Company. To accomplish these purposes, the
Plan provides a means whereby employees, directors and consultants of the
Company and any of its subsidiaries may receive stock options to purchase shares
of the Company's Common Stock ("Options").

         2.       ADMINISTRATION.

         (A) COMPOSITION OF THE COMMITTEE. The Plan shall be administered by a
committee (the "Committee"), which shall be appointed by and serve at the
pleasure of the Company's Board of Directors (the "Board"). The Committee shall
be comprised of two or more members of the Board. In the event that the Company
registers any class of equity securities pursuant to Section 12 of the
Securities Exchange Act of 1934 (the "Exchange Act"), each member of the
Committee shall be (i) a "non-employee director" within the meaning of Rule
16b-3 under the Exchange Act, and (ii) an "outside director" within the meaning
of Section 162(m) of the Internal Revenue Code of 1986, as amended (the "Code").
Subject to the foregoing, from time to time the Board may increase or decrease
the size of the Committee, appoint additional members thereof, remove members
(with or without cause), appoint new members in substitution therefor, fill
vacancies or remove all members of the Committee and thereafter directly
administer the Plan.

         (B) AUTHORITY OF THE COMMITTEE. The Committee shall have full and final
authority, in its sole discretion, to interpret the provisions of the Plan and
to decide all questions of fact arising in its application; to determine the
employees, directors and consultants to whom awards shall be made and the type,
amount, size and terms of each such award; to determine the time when awards
shall be granted; and to make all other determinations necessary or advisable
for the administration of the Plan. The Committee shall have the authority to
adopt, amend and rescind such rules, regulations and procedures as, in its
opinion, may be advisable in the administration of the Plan, including, without
limitation, rules, regulations and procedures that: (i) deal with satisfaction
of an optionee's tax withholding obligations pursuant to Section 13 hereof, (ii)
include arrangements to facilitate an optionee's ability to borrow funds for the
payment of the exercise price of an Option, if applicable, from securities'
brokers and dealers, and (iii) include arrangements that provide for the payment
of some or all of an Option's exercise price by delivery of previously owned
shares of Common Stock or other property and/or by withholding some of the
shares of Common Stock being acquired upon exercise of an Option. All decisions,
determinations and interpretations of
<PAGE>

the Committee shall be final and binding on all optionees and all other holders
of Options granted under the Plan.

         (C) AUTHORITY OF THE BOARD. Notwithstanding anything to the contrary
set forth in the Plan, all authority granted hereunder to the Committee may be
exercised at any time and from time to time by the Board. All decisions,
determinations and interpretations of the Board shall be final and binding on
all optionees and all other holders of Options granted under the Plan.

         3.       STOCK SUBJECT TO THE PLAN.

         Subject to Section 16 hereof, the shares that may be issued under the
Plan shall not exceed in the aggregate 5,000,000 shares of Common Stock of the
Company (the "Common Stock"). Such shares may be authorized and unissued shares
or shares issued and subsequently reacquired by the Company. Except as otherwise
provided herein, any shares subject to an Option that for any reason expires or
is terminated unexercised as to such shares shall again be available under the
Plan.

         4.       ELIGIBILITY TO RECEIVE OPTIONS.

         Persons eligible to receive stock options under the Plan shall be
limited to those consultants to and those officers, directors and other
employees of the Company and any subsidiary (as defined in Section 425 of the
Code or any amendment or substitute thereto) who are in positions in which their
decisions, actions and counsel significantly impact upon the profitability and
success of the Company and/or a subsidiary. Moreover, consultants and directors
who are not also employees shall not be eligible to be awarded Incentive Stock
Options (as defined in Section 5 hereof).

         5.       TYPES OF OPTIONS.

         Grants may be made at any time and from time to time by the Committee
in the form of stock options to purchase shares of Common Stock. Options granted
hereunder may be Options that are intended to qualify as incentive stock options
within the meaning of Section 422 of the Code or any amendment or substitute
thereto ("Incentive Stock Options") or Options that are not intended to so
qualify ("Nonqualified Stock Options").

         6.       STOCK OPTIONS.

         Each Option for the purchase of Common Stock shall be evidenced by a
written option agreement in such form not inconsistent with the Plan as the
Committee shall approve from time to time. The Options granted hereunder may be
evidenced by a single agreement or by multiple agreements, as determined by the
Committee in its sole discretion. Each option agreement shall contain in
substance the following terms and conditions:


         (A) TYPE OF OPTION. Each option agreement shall identify the Options
represented thereby as Incentive Stock Options or Nonqualified Stock Options, as
the case may be.

<PAGE>

         (B) OPTION PRICE. Each option agreement shall set forth the purchase
price of the Common Stock purchasable upon the exercise of the Option evidenced
thereby. Subject to the limitation set forth in Section 6(d)(ii), the purchase
price of the Common Stock subject to an Incentive Stock Option shall be not less
than 100% of the Fair Market Value of such stock on the date the Option is
granted, as determined by the Committee, but in no event less than the par value
of such stock. The purchase price of the Common Stock subject to a Nonqualified
Stock Option shall be not less than 85% of the Fair Market Value of the Common
Stock on the date the Option is granted, as determined by the Committee. The
Fair Market Value on any date shall mean the closing price of the Common Stock,
as reported in The Wall Street Journal (or if not so reported, as otherwise
reported by the National Association of Securities Dealers Automated Quotation
("Nasdaq") System), or if the Common Stock is not reported by Nasdaq, the fair
market value shall be as determined by the Committee in accordance with Section
422 of the Code.

         (C) EXERCISE TERM. Each option agreement shall state the period or
periods of time within which the Option shall vest and may be exercised, in
whole or in part, which shall be such a period or periods of time as may be
determined by the Committee, provided that no Option shall be exercisable after
ten years from the date of grant thereof. Subject to the requirements set forth
in the Plan, the Committee shall have the power to permit: (i) the exercise of
unvested Options, or portions thereof, for the purchase of shares of restricted
Common Stock subject to a repurchase right in favor of the Company, with the
repurchase price being equal to the lesser of (x) the original purchase price or
(y) the Fair Market Value of the shares on the date of repurchase, or to any
other restrictions as the Committee deems to be appropriate, and (ii) the
acceleration of previously established exercise terms, in each case upon such
circumstances and subject to such terms and conditions as the Committee shall
determine.

         (D) INCENTIVE STOCK OPTIONS. In the case of an Incentive Stock Option,
each option agreement shall contain such other terms, conditions and provisions
as the Committee determines necessary or desirable in order to qualify the
Option granted thereunder as a tax-favored Option (within the meaning of Section
422 of the Code or any amendment or substitute thereto or regulation thereunder)
including without limitation, each of the following, except that any of these
provisions may be omitted or modified if it is no longer required in order to
have an Option qualify as a tax-favored Option within the meaning of Section 422
of the Code or any substitute therefor:

                  (i) The aggregate Fair Market Value (determined as of the date
the Option is granted) of the Common Stock with respect to which Incentive Stock
Options are first exercisable by any employee during any calendar year (under
all plans of the Company) shall not exceed $100,000.

                  (ii) No Incentive Stock Options shall be granted to any
employee if at the time the Option is granted such employee owns stock
possessing more than 10% of the total combined voting power of all classes of
stock of the Company or its parent or its subsidiaries unless at the time such
Option is granted the Option price is at least 110% of





<PAGE>

the fair market value of the stock subject to the Option and, by its terms, the
Option is not exercisable after the expiration of five years from the date of
grant.

         (E) SUBSTITUTION OF OPTIONS. Options may be granted under the Plan from
time to time in substitution for stock options held by employees of other
corporations who are about to become, and who do concurrently with the grant of
such options become, employees of the Company or a subsidiary as a result of a
merger or consolidation of the employing corporation with the Company or a
subsidiary, or the acquisition by the Company or a subsidiary of the assets of
the employing corporation, or the acquisition by the Company or a subsidiary of
stock of the subsidiary. The terms and conditions of the substitute Options so
granted may vary from the terms and conditions set forth in this Section 6 to
such extent as the Committee at the time of grant may deem appropriate to
conform, in whole or in part, to the provisions of the stock options in
substitution for which they are granted.

         7.       DATE OF GRANT.

         The date on which an Option shall be deemed to have been granted under
the Plan shall be the date of the Committee's authorization of the Option or
such later date as may be determined by the Committee at the time the Option is
authorized. Notice of the determination shall be given to each individual to
whom an Option is so granted within a reasonable time after the date of such
grant.

         8.       EXERCISE AND PAYMENT FOR SHARES.

         Options may be exercised in whole or in part, from time to time, when
permitted by the respective option agreement, by giving written notice of
exercise to the Secretary of the Company, specifying the number of shares to be
purchased. The purchase price of the shares with respect to which an Option is
exercised shall be payable in full with the notice of exercise in cash, Common
Stock at Fair Market Value, or a combination thereof, as the Committee may
determine from time to time and subject to such terms and conditions as may be
prescribed by the Committee for such purpose. The Committee may also, in its
discretion and subject to prior notification to the Company by an optionee,
permit an optionee to enter into an agreement with the Company's transfer agent
or a brokerage firm of national standing whereby the optionee will
simultaneously exercise the Option and sell the shares acquired thereby through
the Company's transfer agent or such a brokerage firm and either the Company's
transfer agent or the brokerage firm executing the sale will remit the Company
from the proceeds of sale the exercise price of the shares as to which the
Option has been exercised.

         9.       RIGHTS UPON TERMINATION OF SERVICE.

         In the event that an optionee ceases to be an employee or consultant of
the Company or any subsidiary for any reason other than death, retirement, as
hereinafter defined, or disability (within the meaning of Section 72(m)(7) of
the Code or any substitute therefor), the optionee shall have the right to
exercise the Option during its term within a period of three months after such
termination to the extent that the Option

<PAGE>
was vested and exercisable at the time of termination, or within such other
period and subject to such terms and conditions as may be specified by the
Committee; provided, however, that the period during which an Incentive Stock
Option may be exercised may not exceed three months after the date of such
termination. In the event that an optionee dies, retires or becomes disabled
prior to the expiration of his Option and without having fully exercised his
Option, the optionee or his successor shall have the right to exercise the
Option to the extent vested at the time he ceases to be an employee of the
Company, during its term within a period of one year after termination of
employment due to death, retirement or disability to the extent that the Option
was exercisable at the time of termination, or within such other period and
subject to such terms and conditions as may be specified by the Committee. As
used in this Section 9, "retirement" shall apply only to employees and not to
consultants and means a termination of employment by reason of an optionee's
retirement at or after his earliest permissible retirement date pursuant to and
in accordance with his employer's regular retirement plan or personnel
practices.

         10.      GENERAL RESTRICTIONS.

         Each Option granted under the Plan shall be subject to the requirement
that if at any time the Committee shall determine that (i) the listing,
registration or qualification of the shares of Common Stock subject or related
thereto upon any securities exchange or under any state or federal law, or (ii)
the consent or approval of any government regulatory body, or (iii) an agreement
by the recipient of an Option with respect to the disposition of shares of
Common Stock is necessary or desirable as a condition of or in connection with
the granting of such Option or the issuance or purchase of shares of Common
Stock thereunder, such Option shall not be consummated in whole or in part
unless such listing, registration, qualification, consent, approval or agreement
shall have been effected or obtained free of any conditions not acceptable to
the Committee.

         11.      RIGHTS OF A SHAREHOLDER.

         The recipient of any Option under the Plan, unless otherwise provided
by the Plan, shall have no rights as a shareholder unless and until a
certificate for shares of Common Stock is issued and delivered to him.

         12.      RIGHT TO TERMINATE SERVICE.

         Nothing contained in the Plan or in any agreement entered into pursuant
to the Plan shall confer upon any optionee the right to continue in the service
of the Company or any subsidiary as an employee or a consultant or affect any
right that the Company or any subsidiary may have to terminate the employment or
consulting relationship of such optionee.

         13.      WITHHOLDING.

         Whenever the Company proposes or is required to issue or transfer
shares of Common Stock under the Plan, the Company shall have the right to
require the recipient to remit to the Company an amount sufficient to satisfy
any federal, state or local withholding tax requirements prior to the delivery
of any certificate or certificates for
<PAGE>
such shares. If and to the extent authorized by the Committee, in its sole
discretion, an optionee may make an election, by means of a form of election to
be prescribed by the Committee, to have shares of Common Stock that are acquired
upon exercise of an Option withheld by the Company or to tender other shares of
Common Stock or other securities of the Company owned by the optionee to the
Company at the time of exercise of an Option to pay the amount of tax that would
otherwise be required by law to be withheld by the Company as a result of any
exercise of an Option from amounts payable to such optionee. Any such election
shall be irrevocable and shall be subject to the disapproval of the Committee at
any time. Any securities so withheld or tendered will be valued by the Committee
as of the date of exercise.

         14.      NON-ASSIGNABILITY.

         No Option under the Plan shall be assignable or transferable by the
recipient thereof except by will or by the laws of descent and distribution or
by such other means as the Committee may approve. During the life of the
recipient such Option shall be exercisable only by such person or by such
person's guardian or legal representative.

         15.      NON-UNIFORM DETERMINATIONS.

         The Committee's determinations under the Plan (including without
limitation determinations of the persons to receive Options, the form, amount
and timing of such grants, the terms and provisions of Options, and the
agreements evidencing same) need not be uniform and may be made selectively
among persons who receive, or are eligible to receive, grants of Options under
the Plan whether or not such persons are similarly situated.

         16.      ADJUSTMENTS.

         (A) CHANGES IN CAPITALIZATION. Subject to any required action by the
shareholders of the Company, the number of shares of Common Stock covered by
each outstanding Option and the number of shares of Common Stock that have been
authorized for issuance under the Plan but as to which no Options have yet been
granted or which have been returned to the Plan upon cancellation or expiration
of an Option, as well as the price per share of Common Stock covered by each
such outstanding Option, shall be proportionately adjusted for any increase or
decrease in the number of issued shares of Common Stock resulting from a stock
split, reverse stock split, stock dividend, combination or reclassification of
the Common Stock, or any other increase or decrease in the number of issued
shares of Common Stock effected without receipt of consideration by the Company;
provided, however, that conversion of any convertible securities of the Company
shall not be deemed to have been "effected without receipt of consideration."
Such adjustment shall be made by the Committee, whose determination in that
respect shall be final, binding and conclusive. Except as expressly provided
herein, no issuance by the Company of shares of stock of any class, or
securities convertible into shares of stock of any class, shall affect, and no
adjustment by reason thereof shall be made with respect to, the number or price
of shares of Common Stock subject to an Option.



<PAGE>
         (B) DISSOLUTION OR LIQUIDATION. In the event of the proposed
dissolution or liquidation of the Company, all outstanding Options will
terminate immediately prior to the consummation of such proposed action, unless
otherwise provided by the Committee. The Committee may, in the exercise of its
sole discretion in such instances, declare that any Option shall terminate as of
a date fixed by the Committee and give each Option holder the right to exercise
his Option as to all or any part of the shares of Common Stock covered by the
Option, including shares as to which the Option would not otherwise be
exercisable.

         (C) SALE OR MERGER. In the event of a proposed sale of all or
substantially all of the assets of the Company, or the merger of the Company
with or into another corporation, the Committee, in the exercise of its sole
discretion, may take such action as it deems desirable, including, but, not
limited to: (i) causing an Option to be assumed or an equivalent option to be
substituted by such successor corporation or a parent or subsidiary of such
successor corporation, (ii) providing that an Option holder shall have the right
to exercise his Option as to all of the shares of Common Stock covered by the
Option, including shares as to which the Option would not otherwise be vested or
exercisable, or (iii) declare that an Option shall terminate at a date fixed by
the Committee provided that the Option holder is given notice and opportunity
prior to such date to exercise that portion of his Option that is currently
vested and exercisable.

         17.      AMENDMENT.

         The Board may terminate or amend the Plan at any time with respect to
shares as to which Options have not been granted, subject to any required
shareholder approval or any shareholder approval that the Board may deem to be
advisable for any reason, such as for the purpose of obtaining or retaining any
statutory or regulatory benefits under tax, securities or other laws or
satisfying any applicable stock exchange listing requirements. Neither the Board
nor the Committee may, without the consent of the holder of an Option, alter or
impair any Option previously granted under the Plan, except as specifically
authorized herein.

         18.      CONDITIONS UPON ISSUANCE OF SHARES.

         (A) COMPLIANCE WITH SECURITIES LAWS. Shares of the Company's Common
Stock shall not be issued pursuant to the exercise of an Option unless the
exercise of such Option and the issuance and delivery of such shares pursuant
thereto shall comply with all relevant provisions of law, including, without
limitation, the Securities Act of 1933, as amended, the Exchange Act, the rules
and regulations promulgated thereunder, and the requirements of any stock
exchange upon which the Common Stock of the Company may then be listed, and
shall be further subject to the approval of counsel for the Company with respect
to such compliance.

         (B) INVESTMENT REPRESENTATIONS. As a condition to the exercise of an
Option, the Company may require the person exercising such Option to represent
and warrant at the time of any such exercise that the shares of Common Stock are
being purchased only for investment and without any present intention to sell or
distribute such




<PAGE>
shares if, in the opinion of counsel for the Company, such representation is
required by any of the aforementioned relevant provisions of law.

         19.      RESERVATION OF SHARES.

         The Company, during the term of the Plan, will at all times reserve and
keep available such number of shares as shall be sufficient to satisfy the
requirements of the Plan. Inability of the Company to obtain authority from any
regulatory body having jurisdiction, which authority is deemed by the Company's
counsel to be necessary to the lawful issuance and sale of any shares hereunder,
shall relieve the Company of any liability in respect of the failure to issue or
sell such shares as to which such requisite authority shall not have been
obtained.

         20.      EFFECT ON OTHER PLANS.

         Participation in the Plan shall not affect an employee's eligibility to
participate in any other benefit or incentive plan of the Company or any
subsidiary. Any Options granted pursuant to the Plan shall not be used in
determining the benefits provided under any other plan of the Company or any
subsidiary unless specifically provided.

         21.      DURATION OF THE PLAN.

         The Plan shall remain in effect until all Options granted under the
Plan have been satisfied by the issuance of shares, but no Option shall be
granted more than ten years after the earlier of the date the Plan is adopted by
the Board or is approved by the Company's shareholders.

         22.      FORFEITURE FOR DISHONESTY.

         Notwithstanding anything to the contrary in the Plan, if the Committee
finds, by a majority vote, after full consideration of the facts presented on
behalf of both the Company and any optionee, that the optionee has been engaged
in fraud, embezzlement, theft, commission of a felony or dishonest conduct in
the course of his employment or retention by the Company or any subsidiary that
damaged the Company or any subsidiary or that the optionee has disclosed trade
secrets of the Company or any subsidiary, the optionee shall forfeit all
unexercised Options and all exercised Options with respect to which the Company
has not yet delivered the certificates. The decision of the Committee in
interpreting and applying the provisions of this Section 22 shall be final. No
decision of the Committee shall affect the finality of the discharge or
termination of such optionee by the Company or any subsidiary in any manner.

         23.      NO PROHIBITION ON CORPORATE ACTION.

         No provision of the Plan shall be construed to prevent the Company or
any officer or director thereof from taking any corporate action deemed by the
Company or such officer or director to be appropriate or in the Company's best
interest, whether or not such action could have an adverse effect on the Plan or
any Options granted hereunder, and no optionee or optionee's estate, personal
representative or beneficiary shall have any claim





<PAGE>
against the Company or any officer or director thereof as a result of the taking
of such action.

         24.      INDEMNIFICATION.

         With respect to the administration of the Plan, the Company shall
indemnify each present and future member of the Committee and/or the Board
against, and each member of the Committee and the Board shall be entitled
without further action on his part to indemnity from the Company for all
expenses (including the amount of judgments and the amount of approved
settlements made with a view to the curtailment of costs of litigation, other
than amounts paid to the Company itself) reasonably incurred by him in
connection with or arising out of, any action, suit or proceeding in which he
may be involved by reason of his being or having been a member of the Committee
and/or the Board, whether or not he continues to be such member at the time of
incurring such expenses; provided, however, that such indemnity shall not
include any expenses incurred by any such member of the Committee and/or the
Board (i) in respect of matters as to which he shall be finally adjudged in any
such action, suit or proceeding to have been guilty of gross negligence or
willful misconduct in the performance of his duty as such member of the
Committee and/or the Board; or (ii) in respect of any matter in which any
settlement is effected for an amount in excess of the amount approved by the
Company on the advice of its legal counsel; and provided further that no right
of indemnification under the provisions set forth herein shall be available to
or enforceable by any such member of the Committee and/or the Board unless,
within 60 days after institution of any such action, suit or proceeding, he
shall have offered the Company in writing the opportunity to handle and defend
same at its own expense. The foregoing right of indemnification shall inure to
the benefit of the heirs, executors or administrators of each such member of the
Committee and the Board and shall be in addition to all other rights to which
such member may be entitled as a matter of law, contract or otherwise.

         25.      MISCELLANEOUS PROVISIONS.

      (A) COMPLIANCE WITH PLAN PROVISIONS. No optionee or other person shall
have any right with respect to the Plan, the Common Stock reserved for issuance
under the Plan or any Option until a written Option agreement shall have been
executed by the Company and the optionee and all the terms, conditions and
provisions of the Plan and the Option applicable to such optionee (and each
person claiming under or through him) have been met.

         (B) APPROVAL OF COUNSEL. In the discretion of the Committee, no shares
of Common Stock, other securities or property of the Company, or other forms of
payment shall be issued hereunder with respect to any Option unless counsel for
the Company shall be satisfied that such issuance will be in compliance with
applicable federal, state, local and foreign legal, securities exchange and
other applicable requirements.

         (C) COMPLIANCE WITH RULE 16B-3. To the extent that Rule 16b-3 under the
Exchange Act applies to Options granted under the Plan, it is the intent of the
Company that the Plan comply in all respects with the requirements of Rule
16b-3, that any




<PAGE>
ambiguities or inconsistencies in construction of the Plan be interpreted to
give effect to such intention and that if the Plan shall not so comply, whether
on the date of adoption or by reason of any later amendment to or interpretation
of Rule 16b-3, the provisions of the Plan shall be deemed to be automatically
amended so as to bring them into full compliance with such rule.

         (D) UNFUNDED PLAN. The Plan shall be unfunded. The Company shall not be
required to establish any special or separate fund or to make any other
segregation of assets under the Plan.

         (E) EFFECTS OF ACCEPTANCE OF OPTION. By accepting any Option or other
benefit under the Plan, each optionee and each person claiming under or through
him shall be conclusively deemed to have indicated his acceptance and
ratification of, and consent to, any action taken under the Plan by the Company,
the Board and/or the Committee or its delegates.

         (F) CONSTRUCTION. The masculine pronoun shall include the feminine and
neuter, and the singular shall include the plural, where the context so
indicates.

         26.      SHAREHOLDER APPROVAL.

         The Company shall submit the Plan to the shareholders entitled to vote
hereon for approval within twelve months after the date of adoption by the Board
in order to meet the requirements of Section 422 of the Code and the regulations
thereunder. The exercise of any Option granted under the Plan shall be subject
to the approval of the Plan by the shareholders.

Date of Adoption of Plan by Board of Directors -- February 4, 2003.
Date of Approval of Plan by Shareholders -- February 27, 2003.