Document:

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                                                                     EXHIBIT 4.7

                        SECOND LIMITED CONSENT AND WAIVER

         THIS SECOND LIMITED CONSENT AND WAIVER (this "Consent and Waiver") is
made as of the 17th day of September, 2002 by TENNESSEE FARMERS LIFE INSURANCE
COMPANY, a Tennessee corporation licensed to sell life insurance in Tennessee
("Lender"), party to the Credit Agreement (defined below) and the Agreement to
Merge. Terms defined in the Credit Agreement are, unless otherwise defined
herein or the context otherwise requires, used herein as defined in the Credit
Agreement.

                                    RECITALS

         WHEREAS, Donlar Corporation, Donlar Biosyntrex Corporation (each a
"Borrower" and collectively the "Borrowers") and Lender have entered into that
certain Bridge and Consolidated Term Loan Agreement, dated as of March 18, 2002
(as amended or supplemented, the "Credit Agreement") and that certain Agreement
to Merge, dated as of March 18, 2002 (the "Agreement to Merge");

         WHEREAS, pursuant to both the Credit Agreement and the Agreement to
Merge, and as modified by our Limited Consent and Waiver dated August 2, 2002,
the Borrowers have agreed to merge by September 2, 2002 (the "Merger");

         WHEREAS, Borrowers have filed amended proxy material and Registration
Statement on Form S-4 for use in connection with the Merger with the United
States Securities and Exchange Commission ("SEC") and have received a second SEC
comment letter in response to their submission;

         WHEREAS, Borrowers are responding to the SEC comment letter and
anticipate closing the Merger by October 31, 2002 (the "Delayed Merger");

         WHEREAS, Borrowers have requested the Lender to (i) consent to the
Delayed Merger, and (ii) to waive enforcement of Section 5.1, 8.1(b), and 8.1(n)
of the Credit Agreement and Section 1.2 of the Agreement to Merge with regards
thereto;

         NOW THEREFORE, the undersigned Lender hereby (i) consents to the
Delayed Merger, and (ii) waives enforcement of its rights with regards to
Sections 5.1, 8.1(b) and 8.1(n) of the Credit Agreement and Section 1.2 of the
Agreement to Merge, but only with regards violations of such provisions arising
from the Merger not being consummated on or before July 1, 2002, and does not
waive any of Borrowers' other obligations under such provisions, including but
not limited to Borrower's obligations to use best efforts to effect the Merger
as soon as legally possible and in no event later than October 31, 2002.

         This Consent and Waiver shall be a contract made under and governed by
the laws of the State of Tennessee. The Borrowers agree to pay all out-of-pocket
expenses of the Lender and the reasonable fees and expenses of counsel for the
Lender (who may be employed by the Lender) in connection with the preparation of
this Consent and Waiver.

         This Consent and Waiver is limited to its terms and shall not change,
modify, amend or revise the terms, conditions and provisions of the Credit
Agreement or of the Agreement to

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Merge except as expressly provided herein and agreed by the parties hereto. This
Consent and Waiver shall be construed narrowly and does not effect a waiver of
Lender's remedies or rights, except as expressly above described, with regards
to any known or unknown Borrower violation of or default under Credit Agreement
and the Agreement to Merge.

                           [SIGNATURE PAGE TO FOLLOW]

         IN WITNESS WHEREOF, Lender has caused this Limited Consent and Waiver
to be executed by its officer thereunto duly authorized as of the day and year
first above written.

                                         TENNESSEE FARMERS LIFE
                                         INSURANCE COMPANY

                                         By: /s/ Wayne Harris
                                             -----------------------------------
                                         Name: Wayne Harris
                                               ---------------------------------
                                         Title: CFO
                                                --------------------------------

                                       2<PAGE>
                                                                     EXHIBIT 4.8

                   [DONLAR BIOSYNTREX CORPORATION LETTERHEAD]

August 15, 2002

CONFIDENTIAL

Dr. Kamal Modir
3232 Montlake Dr.
Rockford, IL 61114

Dear Dr. Modir:

         The boards of directors of Donlar Corporation ("Donlar") and Donlar's
majority owned subsidiary, Donlar Biosyntrex Corporation ("Donlar Biosyntrex"),
have unanimously approved that certain Amended and Restated Agreement and Plan
of Merger dated as of June 7, 2002 (the "Merger Agreement"), that provides for
the merger of Donlar Biosyntrex with and into Donlar (the "Merger") with Donlar
being the surviving corporation (the "Combined Company"). Currently, you own
5,000 shares of series A preferred stock of Donlar Biosyntrex ("Donlar
Biosyntrex Series A Shares"). This letter agreement (this "Letter Agreement")
sets forth certain understandings between you and Donlar Biosyntrex regarding
the terms upon which you shall surrender the Donlar Biosyntrex Series A Shares
in exchange for 5,000 shares of common stock of the Combined Company ("Combined
Company Common Shares") pursuant to the terms of the Merger Agreement.

         Accordingly, you agree: (a) to surrender for cancellation the Donlar
Biosyntrex Series A Shares in exchange for Combined Company Common Shares issued
upon the completion of the Merger; (b) to vote any shares of voting securities
of Donlar Biosyntrex owned by you in favor of the approval of the Merger and the
equity incentive plan; and (c) to appoint Larry P. Koskan as proxy with full
power of substitution, to vote at the special meeting of the shareholders of
Donlar Biosyntrex, all of the Donlar Biosyntrex Series A Shares which you have
power to vote at the special meeting of shareholders, or any adjournment
thereof, in favor of the approval of the Merger and the equity incentive plan.

         If the foregoing is in accordance with your understanding of our
agreement, please sign where indicated below and deliver a copy of this Letter
Agreement as provided for herein, whereupon this Letter Agreement shall
represent a binding agreement between us and shall be governed by the internal
laws of the State of Illinois.

                                                  Very truly yours,

                                                  DONLAR BIOSYNTREX CORPORATION

                                                  By: /s/ Larry P. Koskan
                                                      -------------------------
                                                  Name: Larry Koskan
                                                        Title: President and CEO

Accepted and agreed to as of the date first above written:

/s/ Kamal Modir, M.D.
---------------------<PAGE>
                                                                     EXHIBIT 4.9

                   [DONLAR BIOSYNTREX CORPORATION LETTERHEAD]

August 15, 2002

CONFIDENTIAL

Mr. Kenneth Hubbard
Hubbard Healthcare
P.O. Box 2210
206 Southgate Dr.
Boone, NC  28607

Dear Mr. Hubbard:

         The boards of directors of Donlar Corporation ("Donlar") and Donlar's
majority owned subsidiary, Donlar Biosyntrex Corporation ("Donlar Biosyntrex"),
have unanimously approved that certain Amended and Restated Agreement and Plan
of Merger dated as of June 7, 2002 (the "Merger Agreement"), that provides for
the merger of Donlar Biosyntrex with and into Donlar (the "Merger") with Donlar
being the surviving corporation (the "Combined Company"). Currently, you own
5,000 shares of series A preferred stock of Donlar Biosyntrex ("Donlar
Biosyntrex Series A Shares"). This letter agreement (this "Letter Agreement")
sets forth certain understandings between you and Donlar Biosyntrex regarding
the terms upon which you shall surrender the Donlar Biosyntrex Series A Shares
in exchange for 5,000 shares of common stock of the Combined Company ("Combined
Company Common Shares") pursuant to the terms of the Merger Agreement.

         Accordingly, you agree: (a) to surrender for cancellation the Donlar
Biosyntrex Series A Shares in exchange for Combined Company Common Shares issued
upon the completion of the Merger; (b) to vote any shares of voting securities
of Donlar Biosyntrex owned by you in favor of the approval of the Merger and the
equity incentive plan; and (c) to appoint Larry P. Koskan as proxy with full
power of substitution, to vote at the special meeting of the shareholders of
Donlar Biosyntrex, all of the Donlar Biosyntrex Series A Shares which you have
power to vote at the special meeting of shareholders, or any adjournment
thereof, in favor of the approval of the Merger and the equity incentive plan.

         If the foregoing is in accordance with your understanding of our
agreement, please sign where indicated below and deliver a copy of this Letter
Agreement as provided for herein, whereupon this Letter Agreement shall
represent a binding agreement between us and shall be governed by the internal
laws of the State of Illinois.

                                                  Very truly yours,

                                                  DONLAR BIOSYNTREX CORPORATION

                                                  By: /s/ Larry P. Koskan
                                                      -------------------------
                                                  Name: Larry Koskan
                                                        Title: President and CEO

Accepted and agreed to as of the date first above written:

/s/ Kenneth S. Hubbard
----------------------<PAGE>
                                                                    EXHIBIT 4.10

                   [DONLAR BIOSYNTREX CORPORATION LETTERHEAD]

August 23, 2002

CONFIDENTIAL

Mr. Peter LeDonne
Plum Creek Farm
46 Linvale Road
Ringoes, NJ  08551

         The boards of directors of Donlar Corporation ("Donlar") and Donlar's
majority owned subsidiary, Donlar Biosyntrex Corporation ("Donlar Biosyntrex"),
have unanimously approved that certain Amended and Restated Agreement and Plan
of Merger dated as of June 7, 2002 (the "Merger Agreement"), that provides for
the merger of Donlar Biosyntrex with and into Donlar (the "Merger") with Donlar
being the surviving corporation (the "Combined Company"). Currently, you own
1,000 shares of series A preferred stock of Donlar Biosyntrex ("Donlar
Biosyntrex Series A Shares"). This letter agreement (this "Letter Agreement")
sets forth certain understandings between you and Donlar Biosyntrex regarding
the terms upon which you shall surrender the Donlar Biosyntrex Series A Shares
in exchange for 1,000 shares of common stock of the Combined Company ("Combined
Company Common Shares") pursuant to the terms of the Merger Agreement.

         Accordingly, you agree: (a) to surrender for cancellation the Donlar
Biosyntrex Series A Shares in exchange for Combined Company Common Shares issued
upon the completion of the Merger; (b) to vote any shares of voting securities
of Donlar Biosyntrex owned by you in favor of the approval of the Merger and the
equity incentive plan; and (c) to appoint Larry P. Koskan as proxy with full
power of substitution, to vote at the special meeting of the shareholders of
Donlar Biosyntrex, all of the Donlar Biosyntrex Series A Shares which you have
power to vote at the special meeting of shareholders, or any adjournment
thereof, in favor of the approval of the Merger and the equity incentive plan.

         If the foregoing is in accordance with your understanding of our
agreement, please sign where indicated below and deliver a copy of this Letter
Agreement as provided for herein, whereupon this Letter Agreement shall
represent a binding agreement between us and shall be governed by the internal
laws of the State of Illinois.

                                                  Very truly yours,

                                                  DONLAR BIOSYNTREX CORPORATION

                                                  By: /s/ Larry P. Koskan
                                                      -------------------------
                                                  Name: Larry Koskan
                                                        Title: President and CEO

Accepted and agreed to as of the date first above written:

/s/ Peter LeDonne
-----------------

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