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                                                                    EXHIBIT 4.12


                             FOREBEARANCE AGREEMENT


         This Agreement (the "Forebearance Agreement"), dated as of March 18,
2003, is made by and between Donlar Corporation, an Illinois corporation (the
"Borrower") and the Tennessee Farmers Life Insurance Company (the "Lender").

                                    RECITALS

         A. The Borrower and the Lender are parties to that certain Bridge and
Consolidated Term Loan Agreement dated March 18, 2002 as amended by that First
Amendment to Bridge and Consolidated Term Loan Agreement dated May 31, 2002 (the
"Term Loan Agreement"). To secure the Obligations, the Borrower has granted the
Lender security interests and liens in substantially all of its assets.

         B. As contemplated by the Term Loan Agreement and the ancillary
documents thereto, Donlar Biosyntrex Corporation merged with Donlar Corporation
effective March 5, 2003, with Donlar Corporation being the surviving
corporation. Pursuant thereto, Donlar Corporation has succeeded to the rights,
privileges, obligations, duties, debts and liabilities of Donlar Biosyntrex
Corporation under the Term Loan Agreement, and henceforth is referred to as the
sole Borrower under the Term Loan Agreement.

         C. Without limiting the generality of its provisions, the Term Loan
Agreement sets forth the terms and conditions of three term loan facilities,
referred to as the Term A Loan, the Term B Loan, and the Term C Loan (also known
as the Bridge Loan). Pursuant to the Term Loan Agreement, Section 3.1(c), the
Term C Loan was due and payable in full by its terms on March 18, 2003. The
Borrower acknowledges that it has not paid the Term C Loan in full.

         D. Pursuant to Section 8.2(a)(i) of the Term Loan Agreement, any Event
of Default (such as the aforementioned failure to pay the Term C Loan in full at
maturity) empowered the Lender to accelerate and cross-accelerate, declaring all
amounts owing under any or all of the Term Loans to be immediately due and
payable. The Borrower acknowledges that, in fact, the Lender was entitled to
accelerate and has accelerated the Term A and Term B Loans and that, as a
result, all three of the Term Loans are presently due and payable in full.

         E. The Borrower has requested a forebearance to and through May 2, 2003
in the Lender's exercise of its rights and remedies under the Term Loan
Agreement and/or applicable law in connection with such existing Events of
Default in order to provide the Borrower with an opportunity to arrange for a
resolution of the Obligations through the sale of the Borrower (an "Acceptable
Strategic Transaction"). Consistent with the foregoing, and without limiting the
generality of the preservation of rights set forth in SECTION 9 hereof, nothing
contained herein is intended or shall be deemed to constitute an acknowledgment,
representation, warranty, covenant, or other agreement on the part of the Lender
that it has agreed or that it will agree to any forebearance beyond May 2, 2003.

         F. The Lender is willing to forebear until May 2, 2003 from exercising
any of its rights and remedies against the Borrower and its property, including
without limitation, any of the Lender's collateral (the "Forebearance"), but
only pursuant to and upon the terms and

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conditions of this Forebearance Agreement, including, without limitation, that
the Forebearance may and/or shall be terminated under certain circumstances as
set forth in SECTION 8 hereof and the acknowledgment by the Borrower that
interest has accrued on the principal amount of the Term Loans on and after
March 18, 2003 to the date hereof at the non-default rate, and shall continue to
accrue thereon at such rates after the date hereof.

         NOW, THEREFORE, in consideration of the premises and of the mutual
agreements and promises herein contained, the Borrower and the Lender agree as
follows:

         1. Adoption and Incorporation of Recitals. The above recitals are
confirmed and adopted by the parties hereto as if set forth herein.

         2. Defined Terms. Capitalized terms used herein which are not otherwise
defined are used with the meanings ascribed to them in the Term Loan Agreement.

         3. Forebearance. Subject to the terms and conditions of this
Forebearance Agreement, including, without limitation, the provisions of SECTION
8 hereof, the Lender hereby agrees to, and extends to the Borrower, the
Forebearance.

         4. General Loan Agreement Compliance. During the Forebearance, the
other provisions of the Term Loan Agreement (including, without limitation,
those pertaining to the continuing accrual of interest at the rates set forth
therein) and the other existing loan documentation shall remain fully operative
and in effect. Specifically, but without limiting the generality of the
foregoing, during the Forebearance, the Borrower shall comply with all
provisions of the Term Loan Agreement and the other existing loan documentation,
including Section 5.2 of the Term Loan Agreement, which requires the Borrower to
supply the Lender with the required Reports, Certificates and Other Information,
except that the Borrower, solely for the limited period of the Forebearance,
shall not be required to timely pay the interest that is due and owing and
otherwise required to be paid pursuant to Section 2.1(c) of the Term Loan
Agreement.

         5. No Waiver of Events of Default. In this Forebearance Agreement, the
Lender waives no Event of Default, whether presently or subsequently existing.
Consistent with, but without limiting the generality of the foregoing, the
Borrower acknowledges that all Obligations are due and owing.

         6. Information Access. In addition to and not in limitation of its
rights under the Term Loan Agreement and other Loan Documents, the Lender,
including through its agents, shall be given regular and complete access to the
Borrower, its books and records, and other information regarding its business
operations, any proposed asset dispositions, and/or any possible strategic
transactions or initiatives. Consistent with, but not in limitation of the
foregoing, the Borrower shall supply the Lender with the names and contact
information of any potential bidders (or other potential investors or strategic
joint venturers or partners), and the Lender (including through its agents) is
hereby authorized (but not obligated) to contact any and all such persons or
entities directly. Further, consistent with, but not in limitation of the
foregoing, the Borrower shall supply the Lender with the names and contact
information of any and all investment bankers assisting the Borrower in any
aspect of its business, and the Lender (including through its agents) is hereby
authorized to contact any and all investment bankers


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directly for regular status reports on those efforts. Further, consistent with,
but not in limitation of the foregoing, the Borrower shall supply the Lender
with a copy of any and all engagement letters. Further, consistent with, but not
in limitation of the foregoing, the Borrower shall supply the Lender with a copy
of any and all letters of intent relating to any possible sale or other
strategic transaction. The Borrower shall supply the Lender with any and all
such information required above within five (5) days of its receipt thereof.
This information shall be delivered to the Lender's attorney as follows: Mr.
Thomas S. Kiriakos, 190 South LaSalle Street, Chicago, IL 60603.

         7. Effectiveness Conditions. In order for this Forebearance Agreement
to be effective this Forebearance Agreement must be completed, executed, and
delivered by the Borrower to the Lender on or before April 10, 2003.

         8. Termination of the Forebearance. Unless extended by a writing signed
by all parties hereto, the Forebearance shall terminate by its own terms on May
2, 2003. Moreover, each of the following shall be a "Forebearance Termination
Event:"

                  (a) the Borrower's failure to comply strictly with any of the
            obligations set forth in the Term Loan Agreement (including, without
            limitation, the Borrower's failure to provide any information
            required by Section 5.2 of the Term Loan Agreement), except solely
            for the Borrower's failure to pay the interest payments as they
            become due and payable pursuant to Section 2.1(c) of the Term Loan
            Agreement;

                  (b) the Borrower's failure to comply strictly with any of the
            obligations set forth in this Forebearance Agreement (including,
            without limitation, the Borrower's failure to timely provide any and
            all information required by SECTION 6 or SECTION 8(a) of this
            Forebearance Agreement);

                  (c) the failure of any of the events set forth in this
            Forebearance Agreement to occur (or not to occur, as the case may
            be) by the deadlines therefor set forth herein;

                  (d) the Lender determines in its reasonable judgment that the
            Borrower has terminated (or is otherwise not rigorously) pursuing an
            Acceptable Strategic Transaction, it being understood that, without
            limiting the generality of the foregoing, the Lender shall be deemed
            to have acted reasonably if it acts based on a statement of the
            Borrower to such effect;

                  (e) the commencement by or against the Borrower of a voluntary
            or involuntary bankruptcy or other insolvency proceeding (including,
            without limitation, a voluntary or involuntary case under federal
            bankruptcy law or an assignment for the benefit of creditors);

                  (f) the Borrower is enjoined, restrained or in any way
            prevented by court order, which has not been dissolved or stayed
            within five business days, from conducting all or a material part of
            its business affairs; or


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                  (g) any other event (including, without limitation, the loss
            of key employees) occurs that, in the reasonable judgment of the
            Lender, threatens its interest in the collateral (including, without
            limitation, the value thereof), threatens the ability of the
            Borrower to successfully pursue an Acceptable Strategic Transaction,
            or threatens the ability of the Borrower to continue as a going
            concern.

Upon the occurrence of any Forebearance Termination Event, the Lender's
obligation to forebear from the exercise of any of its rights against the
Borrower and its property and/or against any guarantor and his, her or its
property, including any of its collateral, shall immediately terminate, and the
Lender shall immediately be entitled without any further action or notice to
exercise any and all of its rights, powers, and remedies against any of such
entities and persons and/or against any of their respective property.

         9. Other Acknowledgments. The Borrower acknowledges (a) that the
Lender, in no manner whatsoever, is committing in this Forebearance Agreement or
otherwise to advance any additional amounts to the Borrower in any form
whatsoever (including, without limitation, in the form of the Lender's honoring
any checks, whether for payroll or otherwise, that are drawn against Lender
accounts maintained by the Borrower at the Lender in which there are
insufficient funds at the time any such checks are presented for payment) and
(b) that the Lender has expressly stated that it has no intention of advancing
any such additional amounts. Consistent with (but not in limitation of) the
foregoing, it is expressly understood that the payment of or any other liability
with respect to any obligations of the Borrower (including, without limitation,
any taxes) shall remain, in all instances, solely the obligations of the
Borrower, and the Lender does not intend to assume and shall not be deemed to
have assumed any liability in connection with any of such Borrower obligations
(including, without limitation, any taxes, whether payroll, income or otherwise
owing by the Borrower) by virtue of any of the provisions of this Forebearance
Agreement or otherwise.

         10. Preservation and No Waiver of Rights. Consistent with, but not in
limitation of, SECTION 5 hereof, this Forebearance Agreement shall not be deemed
a waiver, extension or modification by the Lender of any term or provision of,
or default under, any loan agreement, any promissory note, or any collateral
documents; and except as otherwise expressly provided for herein, the Lender
hereby fully preserves all its rights, powers and remedies against the Borrower
and/or any other person or entity. In addition, nothing contained herein shall
be deemed to be a waiver or abandonment of any Event of Default (whether
presently or subsequently existing), any rights or remedies available to the
Lender under any loan agreement, any promissory note, any collateral documents,
applicable law or otherwise, each of which rights or remedies is hereby
specifically and expressly reserved, including without limitation, the right to
seek judgment against the Borrower and/or any other person or entity, to
foreclose its interest in any stock or other collateral held by the Lender or in
which the Lender has a security interest or other lien, or to take any other
action permitted under the loan documents or applicable law.

         11. Representations. The Borrower hereby represents and warrants to the
Lender that the execution and delivery of this Forebearance Agreement and the
performance by it of its obligations under this Forebearance Agreement are
within its corporate powers, have been duly authorized by all necessary
corporate action, and do not and will not contravene or conflict with


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any provision of law or of its articles of incorporation or its by-laws and that
this Forebearance Agreement constitutes its legal, valid, and binding
obligations and is enforceable in accordance with its terms except as such
enforcement may be limited by bankruptcy, insolvency, reorganization, moratorium
or similar laws now or hereafter in effect relating to creditors' rights
generally or as such enforcement may be limited in equity.

         12. Reliance by the Lender. The parties hereto understand and
acknowledge that this Forebearance Agreement has been executed for the purposes
of inducing the Lender to agree to the Forebearance. Each of the parties hereto
further understands and acknowledges that the Lender is relying on, and would
not have entered into this Forebearance Agreement had it not been for, the
agreements, representations and warranties of the Borrower set forth herein.

         13. Successors and Assigns. Subject to any assignment or other transfer
restrictions set forth in the Term Loan Agreement, any of the other Loan
Documents and herein, this Forebearance Agreement shall be binding upon the
parties hereto and their respective successors and assigns.

         14. Counterparts. This Forebearance Agreement may be executed in any
number of counterparts, each of which will be deemed to be an original, but all
of which together shall constitute one and the same instrument.

         15. Governing Law. This Forebearance Agreement will be governed by the
internal laws of the State of Tennessee, without giving effect to any of the
State's conflicts-of-law provisions.

         16. Notice. Any notice provided for hereunder shall be in writing,
personally delivered, if such notice is to the Borrower to the address shown
below its or his signature hereto, and, if such notice is to the Lender, to the
Lender's attorney as follows: Mr. Thomas S. Kiriakos, 190 South LaSalle Street,
Chicago, IL 60603, and in each instance may be given by facsimile transmission.

         17. Entire Agreement. This Forebearance Agreement contains the entire
understanding of the parties with respect to the subject matter hereof and
supersedes all prior agreements and understandings relating to the subject
matter hereof and shall not be altered, amended or otherwise modified except by
a written instrument signed by the party sought to be thereby bound.

         18. Headings. The headings and captions used herein are provided for
convenience of reference only and shall not be employed in the construction of
this letter agreement.

         19. No Third Party Beneficiaries. This Forebearance Agreement is solely
for the benefit of the parties hereto, and, no provision of this Forebearance
Agreement shall be deemed to confer upon any third parties (including, without
limitation, any other creditors or parties in interest (including equity
holders) of the Borrower) any claim, remedy, liability, reimbursement, cause of
action or other right.

         20. JURY TRIAL. THE BORROWER AND THE LENDER EACH HEREBY VOLUNTARILY AND
INTENTIONALLY WAIVE ANY RIGHT TO A TRIAL BY


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JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM CONCERNING ANY RIGHTS UNDER THIS
FOREBEARANCE AGREEMENT, OR UNDER ANY OTHER DOCUMENT OR AGREEMENT DELIVERED OR
WHICH MAY IN THE FUTURE BE DELIVERED IN CONNECTION THEREWITH, OR ARISING FROM
ANY LENDERING RELATIONSHIP EXISTING IN CONNECTION WITH THE LOAN DOCUMENTS, AND
AGREE THAT ANY SUCH ACTION, PROCEEDING OR COUNTERCLAIM SHALL BE TRIED BEFORE A
COURT AND NOT BEFORE A JURY. THIS PROVISION IS A MATERIAL INDUCEMENT TO THE
LENDER TO ENTER INTO THIS FOREBEARANCE AGREEMENT.

         IN WITNESS WHEREOF, the parties hereto execute and deliver this
Forebearance Agreement on the date first above written.


                                        DONLAR CORPORATION


                                        By:  /s/ Larry P. Koskan
                                             -----------------------------------
                                        Its: President
                                             -----------------------------------
                                        Address: 6502 South Archer Road
                                                 Bedford Park, Illinois 60501
                                                 Attn: Larry Koskan
                                                 Fax:  (708) 563-9212


                                        THE TENNESSEE FARMERS LIFE
                                        INSURANCE COMPANY


                                        By:  /s/ Ed Lancaster
                                             -----------------------------------
                                        Its: Secretary
                                             -----------------------------------
                                        Address: P.O. Box 998
                                                 Columbia, Tennessee 38402
                                                 Attn: Edward K. Lancaster
                                                 Fax:  (931) 840-8640


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